RU2847455C1 - Device and method for automatic adaptation of loudspeaker to listening environment - Google Patents

Abstract

FIELD: acoustics.

SUBSTANCE: device (100) comprises estimation unit (110) configured to estimate the radiation resistance of each transducer from one or more transducers of each loudspeaker from one or more loudspeakers as estimated radiation resistance; or configured to estimate each transducer radiation impedance from one or more transducers of each loudspeaker from one or more loudspeakers as the estimated radiation impedance, said estimated radiation impedance of said transducer comprising estimated radiation resistance information of said transducer. Device (100) further comprises processing unit (120) configured to obtain one or more audio output channels by processing each audio input channel from one or more input audio channels depending on the estimated radiation resistance or depending on the estimated radiation impedance of each of one or more transducers of each of one or more loudspeakers. To estimate the estimated radiation resistance or the estimated radiation impedance of each transducer from one or more transducers of each loudspeaker from one or more loudspeakers, estimation unit (110) is configured to estimate the estimated radiation resistance or estimated impedance of radiation depending on information of estimated sound pressure indicating estimate of sound pressure on said transducer of said loudspeaker, and depending on the estimated speed information indicating the converter speed estimate of said converter of said loudspeaker.

EFFECT: high accuracy of estimation.

78 cl, 28 dwg

Description

The present invention relates to the reproduction of an audio signal and, in particular, to a device and method for automatically adapting a loudspeaker to a listening environment.

A common problem with reproducing audio signals using loudspeakers is that during sound reproduction, the loudspeaker interacts with its surroundings, which are often confined spaces, such as living spaces. Although the words "loudspeaker" or "transducer" are generally used in the singular, the phenomena and principles described generally apply to the use of multiple loudspeakers or multiple transducers, although this is not specifically mentioned in all cases.

Loudspeakers can be optimized during design and production to achieve their intended performance under specific conditions or assumptions (e.g., for a reference position in a reference room, or optimization under anechoic conditions). However, as soon as a loudspeaker is placed in a different environment, its performance is influenced by the surrounding environment. This is primarily due to the fact that the sound generated and emitted by the loudspeaker interacts with, and is thus influenced by, surfaces and objects near the loudspeaker. Such influences include, for example, reflection, absorption, and diffraction. Particularly in the lower frequency range, proximity to boundary surfaces can lead to significant changes in loudspeaker performance.

The acoustic field that is actually formed at a particular listener's position is a combination of all the participating sounds, in particular the direct sound from the loudspeaker plus the reflected sound from the surroundings.

Because the interaction between direct sound and reflected sound is specific to individual combinations of source and receiver positions, the actual performance of a loudspeaker changes with both the position of the loudspeaker and the position of the listener in the actual listening environment.

It is often desirable to have the loudspeaker adjusted to suit the actual listening conditions.

Thus, the performance of a loudspeaker can be adjusted by applying suitable filters for a particular loudspeaker position and a particular listener position.

Typically, the adjustment is carried out according to the state of the art using a measuring microphone in the listening position and, based on the specific test signals, generating frequency correction filters.

If the sound reproduction needs to be adapted over a wider listening area that covers multiple listening positions, then multiple measurements are typically used, such as multi-point measurements.

To find the best compromise frequency correction for the entire domain (measurement), different averaging approaches can be used taking into account multiple measurements.

The above principles require user interaction (for initial setup, and this will be necessary whenever the speaker's position (sometimes even the listener's position) is changed). Furthermore, since the microphone(s) must be positioned within the listening area, they may be built-in. Overall, this isn't very user-friendly or easy to use. Furthermore, even inexperienced users, even those who can set goals, are likely to do something incorrectly.

In addition to single-point measurement or multi-point measurement optimizations, some general listening environment effects on loudspeaker performance can be mitigated according to coarse adjustment principles that do not require specific measurement.

For example, if a speaker is positioned near a wall, this will result in increased low-frequency output. Some speakers address this issue by providing DIP switches that can activate preset filters designed to handle such common scenarios.

However, these types of settings require the user to have some expert knowledge to select the correct settings. Furthermore, they are not very flexible.

With the advent of wireless portable speakers that can be easily moved to various positions, principles that adapt the speaker to its actual placement, which have favorable results over a large listening area, are desirable. Such frequency correction can be achieved using a circuit that focuses on global frequency correction, taking into account the effects of the room on the reproduced/generated acoustic field. These corrections can be measured at one position but are generally valid throughout the entire room.

The state-of-the-art includes methods that evaluate a global response, which identifies characteristics that apply to the entire listening environment (i.e., they correspond to the average obtained from multiple single-point measurements across the entire room). Thus, by frequency-correcting these global characteristics, it is possible to preferentially adapt a loudspeaker to a specific room and its current installation position, which is favorable for listeners throughout the entire room. These described principles have been used to automatically adapt loudspeakers to their environment.

The state of the art suggests that the calculation of global frequency correction can be based on the assessment of sound pressure and velocity to estimate the frequency-dependent radiation resistance, in particular, the real part of the frequency-dependent radiation impedance.

To measure or estimate the radiation impedance, information about the pressure and normal surface velocity at the source is required. According to the prior art, this can be achieved through processing

- two signals of measured pressure,

- one signal of measured pressure and one signal of measured displacement,

- one signal of measured pressure and one signal of measured speed,

- one signal of measured pressure and one signal of measured acceleration, or

- one signal of measured pressure and one signal of measured current.

According to the prior art, measuring, for example, using two microphones to output a speed signal, or outputting a speed signal based on, for example, a measured current is called evaluation.

US 2002/0154785 A1 describes a method and apparatus for controlling the performance of a loudspeaker in a room. The method comprises the steps of determining the acceleration, velocity, or displacement of a loudspeaker membrane and the sound pressure in front of the membrane in a reference acoustic environment, and determining, based on these values, the radiation resistance, the radiated acoustic power, or the real part of the acoustic wave impedance. The same parameters are measured in the actual listening environment, and their ratio is used to control a correction filter. The overall procedure is based on the understanding of the existence of a strong relationship between the sound manner of a loudspeaker, in particular in the bass range, and its radiation resistance as a function of frequency, which is the real part of the radiation impedance. According to US 2002/0154785 A1, the parameters are measured in the first environment and the same parameters are measured in the second environment, the ratio of their measurements being used to set the correction filter. In summary, US 2002/0154785 A1 relates to a method for controlling the performance of a loudspeaker in a room, wherein in a first acoustic environment, the resulting movement of the loudspeaker transducer membrane and the associated force developed by the acoustic field in the room acting on it are determined by measuring suitable parameters defining a first complex transfer function. In a second acoustic environment, a second complex transfer function is determined by measuring the same or different room-related parameters of the loudspeaker transducer. The ratio between the real parts of the first and second transfer functions is used to set the performance of a correction filter. The filter is applied in a signal processing chain connected to the loudspeaker transducer.

WO 00/21331 A1 describes that, to ensure the adaptability of a loudspeaker to its environment, measuring the velocity or acceleration of the loudspeaker diaphragm and the associated sound pressure in front of the diaphragm requires an accelerometer and a microphone to determine the diaphragm's radiation resistance. WO 00/21331 A1 further stipulates that these two sensors must be expensive to ensure stable behavior over a long service life. Thus, the possibility of replacing the accelerometer with another microphone located at a small distance from the diaphragm is presented. This is based on the idea that changes in radiation resistance can be based on measuring sound pressure at two (or more) points separated by different distances from the loudspeaker diaphragm. Furthermore, WO 00/21331 A1 presents the possibility of using a single microphone that is physically moved to different positions. In summary, WO 00/21331 A1 relates to a loudspeaker of the type having a recording means for determining the radiation resistance of a membrane, expressed through the velocity/acceleration of the loudspeaker membrane and the sound pressure at a distance from the membrane. Thus, via a signal processing unit, a control signal is provided to a filtering unit, which regulates the operating parameters of the loudspeaker with the ability to adapt to the acoustic characteristics of the listening room. The mentioned sensors comprise a microphone for recording the said sound pressure. The recording equipment comprises microphone means for recording the sound pressure at at least two points, differently separated from the membrane, and is provided with transfer means, allowing the same microphone to be effectively and sequentially exposed to the sound pressure at each of the at least two points. In WO 00/21331 A1, the two measurement points mentioned herein must indeed be located near the membrane. As the distance increases, the assessment will be increasingly less accurate. Furthermore, WO 00/21331 A1 states that it is sufficient to obtain a reference value, i.e. the absolute radiation resistance without taking into account the scale factor, for comparison with later sound pressure readings at the same two (or more) points.

US 2017/0195790 A1 describes a loudspeaker system with an external microphone outside the loudspeaker enclosure and an internal microphone inside the loudspeaker enclosure. The transfer function for the frequency correction filter is determined in accordance with the signals from the external and internal microphones. The external microphone(s) [one, two, or more] are positioned to measure the acoustic pressure near the transducer. The internal microphone is used to indirectly measure the volume velocity of the loudspeaker diaphragm.

In summary, according to the prior art, volumetric velocity is estimated based on the sound pressure gradient in front of the loudspeaker (requiring either two very similar measuring devices, moving parts, or an accelerometer). Global frequency correction solutions can be based on an estimate of the sound pressure in front of the loudspeaker and volumetric velocity. Sound pressure can be measured using a microphone near/in front of the loudspeaker (i.e., in front of the cone/transducer/diaphragm). Volumetric velocity estimation is described based on an estimate of the sound pressure gradient in front of the loudspeaker (e.g., using two microphones or a single microphone with a mechanical means for using this single microphone for measurements at two spatially separated positions).

The objective of the present invention is to create improved concepts for reproducing an audio signal. The objective of the present invention is achieved by means of the device according to claim 1, by means of the device according to claim 70, by means of the method according to claim 75, by means of the method according to claim 76, and by means of the computer program according to claim 77.

A device is provided for processing an input audio signal comprising one or more input audio channels to obtain an output audio signal comprising one or more output audio channels, according to an embodiment. The device comprises an estimator configured to estimate the radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation resistance; or configured to estimate the radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation impedance, wherein said estimated radiation impedance of said transducer contains estimated information about the radiation resistance of said transducer. Furthermore, the device comprises a processing unit configured to obtain one or more output audio channels by processing each input audio channel of one or more input audio channels depending on the estimated radiation resistance or depending on the estimated radiation impedance of each of the one or more transducers of each of the one or more loudspeakers. In order to evaluate the estimated radiation resistance or the estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the evaluation unit is configured to evaluate the estimated radiation resistance or the estimated radiation impedance depending on the estimated sound pressure information indicating the estimated sound pressure on said transducer of said loudspeaker, and depending on the estimated speed information indicating the estimated speed of the transducer of said transducer of said loudspeaker.

Furthermore, a method for processing an input audio signal comprising one or more input audio channels is provided to obtain an output audio signal comprising one or more output audio channels, according to an embodiment. The method comprises:

- an estimate of the radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation resistance; or an estimate of the radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation impedance, wherein said estimated radiation impedance of said transducer contains estimated information about the radiation resistance of said transducer, and:

- obtaining one or more output audio channels by processing each input audio channel from one or more input audio channels depending on the estimated radiation resistance or depending on the estimated radiation impedance of each of the one or more transducers of each of the one or more loudspeakers.

In order to estimate the estimated radiation impedance or the estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimated radiation resistance or the estimated radiation impedance is estimated depending on the estimated sound pressure information indicating the estimated sound pressure on said transducer of said loudspeaker, and depending on the estimated speed information indicating the estimated speed of the transducer of said transducer of said loudspeaker.

Furthermore, a device is provided that contains an evaluation unit. The evaluation unit is configured to evaluate the first radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a first estimated radiation resistance before a first point in time; or is configured to evaluate the first radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a first estimated radiation impedance before a first point in time, wherein said first estimated radiation impedance of said transducer contains estimated information about the first radiation resistance of said transducer. In order to estimate the first estimated radiation resistance or the first estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit is configured to estimate the first estimated radiation resistance or the first estimated radiation impedance depending on the information of the first estimated sound pressure, indicating the estimate of the sound pressure on said transducer of said loudspeaker before the first moment in time, and depending on the information of the first estimated speed, indicating the estimate of the first speed of the transducer of said transducer of said loudspeaker before the first moment in time. Furthermore, the estimating unit is configured to estimate the second radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as the second estimated radiation resistance after the second moment in time; or is configured to evaluate the second radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a second estimated radiation impedance after a second time, wherein said second estimated radiation impedance of said transducer comprises estimated information about the second radiation resistance of said transducer. The second time occurs after the first time. To evaluate the second estimated radiation resistance or the second estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit is configured to evaluate the second estimated radiation resistance or the second estimated radiation impedance depending on the information of the second estimated sound pressure indicating the estimate of the sound pressure on said transducer of said loudspeaker after the second time, and depending on the information of the second estimated speed indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker after the second time. Furthermore, the evaluation unit is configured to determine and output whether the device is in the first state or the second state, depending on the radiation resistance difference, indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance, or depending on the radiation impedance difference, indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance. The second state indicates that the device is not operating correctly or that the device has changed location. The first state indicates that the device is operating correctly and that the device has not changed location.

In addition, a method is provided. The method comprises:

- estimating the first radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a first estimated radiation resistance before a first point in time; or estimating the first radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a first estimated radiation impedance before a first point in time, wherein said first estimated radiation impedance of said transducer contains estimated information about the first radiation resistance of said transducer; wherein for estimating the first estimated radiation resistance or the first estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers. The estimation of the first estimated radiation resistance or the first estimated radiation impedance is carried out depending on the information of the first estimated sound pressure indicating the estimate of the sound pressure on said transducer of said loudspeaker before the first point in time, and depending on the information of the first estimated speed indicating the estimate of the first speed of the transducer of said transducer of said loudspeaker before the first point in time.

- estimating the second radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a second estimated radiation resistance after a second time; or estimating the second radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a second estimated radiation impedance after a second time, wherein said second estimated radiation impedance of said transducer contains estimated information about the second radiation resistance of said transducer; wherein for estimating the second estimated radiation resistance or the second estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers. The second time occurs after the first time. The second estimated radiation resistance or the second estimated radiation impedance is estimated depending on the second estimated sound pressure information indicating the estimate of the sound pressure on said transducer of said loudspeaker after the second time, and depending on the second estimated speed information indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker after the second time, and:

- determining and deducing whether the device is in a first state or a second state, depending on a difference in radiation resistances indicating a difference between a second estimated radiation resistance and a first estimated radiation resistance, or depending on a difference in radiation impedances indicating a difference between a second estimated radiation impedance and a first estimated radiation impedance, wherein the second state indicates that the device is not working properly or that the device has changed location, and the first state indicates that the device is working properly and that the device has not changed location.

In addition, a computer program is provided that is designed to implement one of the above-described methods when executed on a computer or signal processor.

Embodiments of the present invention are described in more detail below with reference to the drawings, in which:

Fig. 1 shows a device according to an embodiment.

Fig. 2 shows a system according to an embodiment.

Fig. 3 shows an example loudspeaker with three different measurement positions indicated.

Fig. 4 depicts a high-level illustration of an embodiment.

Fig. 5 shows some illustrative real-world results for a particular loudspeaker at different positions in the same room according to embodiments.

Fig. 6 shows the amplitude-frequency response of the global frequency correction filter after interpolation according to a specific example, and further shows the band limitation for a specific example.

Fig. 7 depicts a high resolution display of a raw prototype filter according to an embodiment.

Fig. 8 demonstrates the use of models to estimate parameters according to an embodiment.

Fig. 9 shows a linear lumped parameter model according to an embodiment.

Fig. 10 shows a side view of an alternative arrangement of a loudspeaker with transducers/transducers on four sides according to an embodiment.

Fig. 11 shows a top view of an alternative arrangement of a loudspeaker with transducers/transducers on four sides according to an embodiment.

Fig. 12 shows an alternative arrangement of a multi-microphone bar-type loudspeaker according to an embodiment.

Fig. 13 shows an example of a loudspeaker located on a surface according to an embodiment.

Fig. 14 shows a top view of the loudspeaker showing possible positions for one or multiple microphones according to an embodiment.

Fig. 15 shows a side view of the loudspeaker showing possible positions for one or multiple microphones according to an embodiment.

Fig. 16 shows another side view of the loudspeaker showing possible positions for one or multiple microphones according to another embodiment.

Fig. 17 shows the amplitude-frequency response of the global frequency correction filter after applying an additional user-specified target frequency correction curve.

Fig. 18 shows an evaluation of the radiation impedance and/or radiation resistance according to another embodiment, depending on one microphone.

Fig. 19 shows an estimation of the radiation impedance and/or radiation resistance according to a further embodiment, depending on one pressure measurement from one microphone.

Fig. 20 shows a comparison of the measured normalized pressure and the measured normalized acceleration.

Fig. 21 shows the average normalized pressure-acceleration ratio when measured indoors (indoors).

Fig. 22 shows a comparison of the phase of the radiation impedance in a free field and in a room as a function of frequency.

Fig. 23 shows the phase angle gradient of the pressure signal.

Fig. 24 shows a comparison of the free field and room radiation resistances for the first loudspeaker.

Fig. 25 shows a comparison of the free field and room radiation resistances for the second loudspeaker.

Fig. 26 shows a comparison of the free field and room radiation resistances for the third loudspeaker.

Fig. 27 shows a comparison of the free-field and room radiation resistances for the fourth loudspeaker.

Fig. 28 shows an overview of the evaluation process according to an embodiment.

Fig. 1 shows a device 100 for processing an input audio signal comprising one or more input audio channels to obtain an output audio signal comprising one or more output audio channels, according to an embodiment.

The device 100 comprises an evaluation unit 110. The evaluation unit 110 is configured to evaluate the radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation resistance; or is configured to evaluate the radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation impedance. The said estimated radiation impedance of the said transducer contains estimated information about the radiation resistance of the said transducer.

In addition, the device 100 comprises a processing unit 120 configured to obtain one or more output audio channels by processing each input audio channel from one or more input audio channels depending on the estimated radiation resistance or depending on the estimated radiation impedance of each of the one or more transducers of each of the one or more loudspeakers.

In order to estimate the estimated radiation resistance or the estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit 110 is configured to estimate the estimated radiation resistance or the estimated radiation impedance depending on the estimated sound pressure information indicating the estimate of the sound pressure on said transducer of said loudspeaker, and depending on the estimated speed information indicating the estimate of the speed of the transducer of said transducer of said loudspeaker.

For example, one or more audio output channels may, for example, represent one or more speaker signals that may, for example, be fed to one or more speakers.

For example, the radiation impedance of a transducer can be represented in the complex domain, for example, by a set of complex values (for example, elements ). The radiation resistance of the transducer can be represented, for example, in the real domain, for example, by a set of real values (for example, elements ). For example, for each complex value from the set of complex values of the transducer radiation impedance, the real part (as opposed to the imaginary part) of said complex value may, for example, represent information about the radiation resistance expressed by said complex value. Or, in other words, if the set of complex values represents information about the radiation impedance, the real parts of the set of complex values may, for example, represent information about the radiation resistance.

In some embodiments, each of the one or more input audio channels and/or one or more output audio signals may be, for example, one or more (traditional/conventional) audio channel signals.

In some other embodiments, each of the one or more input audio channels and/or one or more output audio signals may be, for example, one or more audio object signals.

In some additional embodiments, one or more input audio channels and/or one or more output audio channels may comprise, for example, at least one traditional/conventional audio channel signal and at least one audio object signal.

The above-mentioned one or more audio object signals and/or at least one audio object signal may be, for example, one or more spatial audio object coding (SAOC) object signals.

In some other embodiments, at least one of the one or more input audio channels and/or one or more output audio signals may comprise, for example, scene-based audio information.

In some embodiments, a loudspeaker may include, for example, a transducer for converting electrical signals into sound. Such a transducer (of a specific design) may comprise, for example, a cone/diaphragm. Such a transducer may, for example, be integrated into the housing.

Thus, according to some embodiments, the loudspeaker may comprise, for example, a transducer and a housing.

In some embodiments, the transducer may be, for example, implemented as a moving transducer membrane.

According to some embodiments, one or more speakers mentioned herein and/or one or more microphones mentioned herein may be, for example, installed in a sound bar, in a smart speaker, in a television, in a laptop computer, in a single speaker system.

In some embodiments, at least one of the one or more speakers may be, for example, a subwoofer.

According to an embodiment, one or more microphones may be, for example, remote from said loudspeaker or from said transducer of said loudspeaker.

According to an embodiment, in order to estimate the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker, the estimating unit 110 may, for example, be configured to estimate the estimated radiation resistance or the estimated radiation impedance by estimating the estimated sound pressure information indicating the estimated sound pressure on said transducer of said loudspeaker, and/or by estimating the estimated speed information indicating the estimated speed of the transducer of said transducer of said loudspeaker.

According to an embodiment, the estimating unit 110 may, for example, be configured to evaluate the estimated sound pressure information in such a way that the estimated sound pressure information is represented in the spectral domain; and/or the estimating unit 110 may, for example, be configured to evaluate the estimated speed information in such a way that the estimated speed information is represented in the spectral domain. Furthermore, the estimating unit 110 may, for example, be configured to evaluate the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker in such a way that the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker is represented in the spectral domain.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated sound pressure information depending on the sound pressure on a microphone from one or more microphones.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated speed information as a function of the current through the coil of the loudspeaker transducer of said loudspeaker transducer.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated speed information depending on the electrical resistance , inductance coils, power coefficient , mechanical mass , full rigidity , mechanical resistance . denotes cone speed/transducer speed.

According to an embodiment, the estimator 110 may, for example, be configured to determine the estimated speed information based on a system of equations defined according to:

Where denotes the excitation signal, t denotes time,

x denotes the axial displacement of the loudspeaker membrane of the said loudspeaker,

denotes the current through the coil of the loudspeaker transducer of the said loudspeaker transducer,

where is the designation represents the first derivative with respect to time.

According to an embodiment, the evaluation unit 110 may, for example, be configured to solve the system of equations using the fourth-order Runge-Kutta method.

According to another embodiment, the estimated speed information may, for example, be stored in device 100.

According to an embodiment, the estimated speed information may, for example, be stored in a lookup table that is stored in the device 100. The estimation unit 110 may, for example, be configured to output the estimated speed information from the lookup table.

According to an embodiment, the estimator 110 may, for example, be configured to determine the linear parameters of said transducer of said loudspeaker by solving a minimization/optimization problem for estimating the estimated radiation resistance or estimated radiation impedance of said transducer of said loudspeaker. For example, the linear parameters may, for example, be used for modeling, as described herein.

According to an embodiment, the estimating unit 110 may, for example, be configured to use said estimated sound pressure information to estimate said estimated speed information.

According to an embodiment, the evaluation unit 110 may, for example, be configured to use

Where - the time derivative of the estimated velocity information, - gradient operator, - information on estimated sound pressure in the time domain, - density of the medium.

For example, may, for example, denote pressure information in the time domain; whereas may, for example, denote pressure information in the spectral domain, such as the frequency domain.

According to an embodiment, the processing unit 120 may, for example, be configured to determine the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance. The processing unit 120 may, for example, be configured to process one or more input audio channels depending on the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance.

According to an embodiment, the processing unit 120 may, for example, be configured to change the spectral shape of at least one of the one or more input audio channels depending on the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance to obtain one or more output audio signals.

According to an embodiment, the processing unit 120 may, for example, be configured to determine a spectral change factor for each spectral band of a plurality of spectral bands depending on the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance for said spectral band. For each input audio channel of one or more input audio channels, in order to obtain one of the one or more output audio channels, the processing unit 120 may, for example, be configured to apply the spectral change factor of each spectral band of the plurality of spectral bands to said spectral band of said input audio channel.

According to an embodiment, the processing unit 120 may, for example, be configured to determine the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance according to

Where denotes the mentioned difference, denotes the estimated radiation resistance, denotes the given radiation resistance, denotes the angular frequency.

According to an embodiment, processing unit 120 may, for example, be configured to apply a smoothing operation to said difference, which is the raw filter prototype, to obtain a smoothed filter prototype. Furthermore, processing unit 120 may, for example, be configured to apply the smoothed filter prototype to at least one of the one or more input audio channels to obtain at least one of the one or more output audio channels.

According to an embodiment, the processing unit 120 may, for example, be configured to apply a global frequency equalizer to at least one of the one or more input audio channels to obtain at least one intermediate signal. Furthermore, the processing unit 120 may, for example, be configured to determine the relative sound power in the spectral domain from the estimated radiation resistance or from the estimated radiation impedance. Furthermore, the processing unit 120 may, for example, be configured to determine one or more peaks (e.g., one or more local maxima) in the relative sound power in the spectral domain. Furthermore, the processing unit 120 may, for example, be configured to apply an additional frequency equalizer to at least one intermediate signal depending on one or more peaks in the relative sound power in the spectral domain to obtain at least one of the one or more output audio channels.

According to an embodiment, the estimator 110 may, for example, be configured to evaluate the estimated sound pressure information depending on the captured sound pressure information recorded by one or more microphones.

According to an embodiment, one or more microphones represent two or more microphones. Estimation unit 110 may, for example, be configured to receive captured sound pressure information from two or more microphones. Furthermore, estimation unit 110 may, for example, be configured to use the captured sound pressure information from only one of the two or more microphones to determine the estimated sound pressure information. Furthermore, estimation unit 110 may, for example, be configured to not use the captured sound pressure information from the other microphones of the two or more microphones to determine the estimated sound pressure information.

According to an embodiment, one or more microphones represent two or more microphones. The estimator 110 may, for example, be configured to receive captured sound pressure information from two or more microphones. Furthermore, the estimator 110 may, for example, be configured to determine an average or weighted average of the captured sound pressure information from the two or more microphones, and to determine the estimated sound pressure information using the average or weighted average of the captured sound pressure information.

For example, given two values p ₁ and p ₂ of sound pressure, the average can be expressed, for example, in the form: a = 0.5 p ₁ + 0.5 p ₂ ; and the weighted average a _w with weighting coefficients w ₁ and w ₂ can be expressed, for example, in the form a _w = w ₁ p ₁ + w ₂ p ₂ . For example, 0 < w ₁ < 1 and w ₂ = 1 - w ₁ .

For example, if there are three values p ₁ and p ₂ and p ₃ of sound pressure, the average can be expressed, for example, in the form: a = 1/3 p ₁ + 1/3 p _{2 +} 1/3 p ₃ ; and the weighted average a _w with weighting coefficients w ₁ and w ₂ and w ₃ can be expressed, for example, in the form a _w = w ₁ p ₁ + w ₂ p ₂₊ w ₃ p ₃ . For example , 0 < w ₁ <1; 0 < w ₂ <1;

0 < w ₁ +w ₂ <1 and w ₃ =1 - w ₁ - w ₂ .

According to an embodiment, one or more microphones may, for example, be two or more microphones. One or more loudspeakers may, for example, be two or more loudspeakers, and/or at least one of the one or more loudspeakers may comprise, for example, two or more transducers. The estimating unit 110 may, for example, be configured to receive the captured sound pressure information from two or more microphones. Furthermore, the estimating unit 110 may, for example, be configured to determine, for each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers, a weighted average of the captured sound pressure information from the two or more microphones, and to determine the estimated sound pressure information using the weighted average of the captured sound pressure information, wherein the estimating unit 110 may, for example, be configured to determine said weighted average depending on a plurality of weighting factors, wherein each weighting factor of the plurality of weighting factors depends on the position of said transducer and depends on the position of each of the two or more microphones.

According to an embodiment, one or more microphones may, for example, be two or more microphones. One or more loudspeakers may, for example, be two or more loudspeakers, and/or at least one of the one or more loudspeakers may comprise, for example, two or more transducers. For each transducer of the one or more transducers of the one or more loudspeakers, the estimator 110 may, for example, be configured to select one of the two or more microphones as the selected microphone. For said transducer, the estimator 110 may, for example, be configured to use the captured sound pressure information from the selected microphone to determine the estimated sound pressure information. Furthermore, for said transducer, the estimator 110 may, for example, be configured to not use the captured sound pressure information from other microphones of the two or more microphones to determine the estimated sound pressure information.

According to an embodiment, the estimator 110 may, for example, be configured to determine the estimated sound pressure information using a complex transfer function.

According to an embodiment, the evaluation unit 110 may, for example, be configured to determine the estimated sound pressure information according to , Where indicates the estimated sound pressure information, indicates the captured sound pressure information, indicates the complex transfer function given by

Where denotes the angular frequency, (for example, ), denotes the applied sound pressure at the said loudspeaker, indicates the estimated/simulated sound pressure at said one of the one or more microphones that is present when the sound pressure exists on the loudspeaker. And can, for example, be obtained from an acoustic model.

According to an embodiment, for each transducer of one or more transducers of one or more loudspeakers, the evaluation unit 110 may, for example, be configured to select one of two or more microphones as the selected microphone depending on the position of said transducer and depending on the position of each of the two or more microphones.

According to an embodiment, one or more input audio channels may, for example, represent two or more input audio channels, and one or more output audio channels may, for example, represent two or more output audio channels. The processing unit 120 may, for example, be configured to obtain at least two of the two or more output audio channels by determining, depending on the estimated radiation resistance or depending on the estimated radiation impedance of at least one of the one or more transducers of each of the one or more loudspeakers, individual change information for each input audio channel of at least two of the two or more input audio channels; and by applying the individual change information for each input audio channel of at least two of the two or more input audio channels on said input audio channel.

Thus, in this embodiment, different input audio channels are processed differently. For example, for a 5.1 input audio signal, it may be desirable to boost the bass frequencies for the LFE channel and attenuate the bass for the other channels.

Thus, if the estimated radiation resistance indicates, for example, that the placement of a loudspeaker results in a boost in bass frequencies, this may, for example, be preferentially maintained for the LFE or subwoofer channel, while being reduced for the other channels.

Furthermore, it's not always desirable to suppress the acoustic properties of a room. Some audio input channels can, for example, be modified to preferentially take the acoustic properties of the room into account.

For example, it may sometimes be beneficial to boost or enhance the high frequency components of an audio signal, such as those reproduced using one or more tweeters, rather than reducing the low frequency/bass components of the audio signal, since such a strategy may, for example, result in a more expressive sound perception, or, for example, since the loudspeaker may output a higher level/gain overall, while the given adaptation of the frequency curve still follows the given target.

Additionally, different loudspeaker transducers can be designed/optimized for different frequency ranges, such as woofers, full-range transducers, tweeters, etc.

This differentiation can be taken into account in the design of one or more reference curves, for example, one or more target curves, or specified goals. And/or, this differentiation can be taken into account in the design of one or more objectives.

According to an embodiment, at least one of the one or more microphones 300 is not located in the main direction of radiation from any of the one or more loudspeakers 200.

According to an embodiment, at least one of the one or more microphones 300 does not have a direct line of sight to any of the one or more loudspeakers 200.

According to an embodiment, for each microphone of one or more microphones, the specified distance between said microphone and the loudspeaker may be, for example, at least 10 centimeters, for example, at least 20 centimeters, for example, at least 50 centimeters, for example, at least 1 meter. Even with these distances, the principles of the invention still operate, for example, due to the provided evaluation principles.

According to an embodiment, the estimator 110 may, for example, be configured to update the estimated radiation resistance or the estimated radiation impedance from one or more transducers of one or more loudspeakers upon/during initialization and/or upon request and during operation.

For example, the estimated radiation resistance or the estimated radiation impedance can, for example, be estimated when the device is moved in the listening environment, for example in a room, and can, for example, also be updated periodically (and not only during initialization).

According to an embodiment, the estimated radiation resistance is the first estimated radiation resistance before the first time, or the estimated radiation impedance is the first estimated radiation impedance before the first time. The estimator 110 may, for example, be configured to estimate the second radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as the second estimated radiation resistance after the second time; or be configured to estimate the second radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as the second estimated radiation impedance after the second time, wherein said second estimated radiation impedance of said transducer contains estimated information about the second radiation resistance of said transducer. The second time occurs after the first time. In order to estimate the second estimated radiation resistance or the second estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit 110 may, for example, be configured to estimate the second estimated radiation resistance or the second estimated radiation impedance depending on the information of the second estimated sound pressure, indicating the estimate of the second sound pressure on said transducer of said loudspeaker, and depending on the information of the second estimated speed, indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker. Furthermore, the estimating unit 110 may, for example, be configured to determine and output whether the device 100 is in the first state or in the second state, depending on the difference in the radiation resistances, indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance, or depending on the difference in the radiation impedances, indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance. The second state indicates that device 100 is not functioning properly or that device 100 has changed location. The first state indicates that device 100 is functioning properly and that device 100 has not changed location.

According to an embodiment, the estimating unit 110 may, for example, be configured to estimate the second estimated sound pressure information depending on the captured second sound pressure information recorded by one or more microphones; and/or the estimating unit 110 may, for example, be configured to estimate the second estimated speed information depending on the second current through the coil of the transducer of the loudspeaker of said transducer of said loudspeaker after the second time.

According to an embodiment, additionally another means, for example, one or more gyroscopes, or other information collected from the pressure measurement, may, for example, also be used as an indication that the device has moved.

Fig. 2 shows a system according to an embodiment. The system comprises a device 100, described above with reference to Fig. 1, and a loudspeaker 200 mentioned above. The loudspeaker 200 is configured to output at least one of one or more output audio channels.

According to an embodiment, the system may, for example, further comprise one or more of the above-mentioned microphones 300.

Further, additional principles and additional embodiments of the present invention are provided.

In some embodiments, the microphone does not need to be positioned near or in front of the speaker diaphragm to measure sound pressure.

In some embodiments, it may be assumed, for example, that at least one microphone is located somewhere on the loudspeaker housing. At least one microphone may also be located near the loudspeaker, provided the setup is known, allowing for the transmission path of sound from the diaphragm to the at least one microphone to be modeled. Using the modeling results for this specific configuration, the sound pressure present near the diaphragm can be determined.

Some embodiments may, for example, not require sound pressure gradient measurements (which require two microphones) or acceleration measurements to measure volumetric velocity.

In some embodiments, volumetric velocity can be estimated, for example, based on an electromechanical model of the loudspeaker. This model is fed with measurements of the voltage/current applied to the loudspeaker terminals during operation.

Some embodiments provide principles that enable the automatic adaptation of the playback characteristics of an audio signal playback system to the playback environment. This automatic adaptation of the playback system may, for example, take the form of automatically calibrating the playback system's timbral characteristics according to a specific listening environment and speaker position.

Typically, during the design, manufacture, and setup of a new device, the enclosure geometry and transducer configuration (sources and receivers, e.g., loudspeakers and/or microphones) are known. Some embodiments may, for example, utilize these known properties to achieve a favorable method for calibrating the acoustic system in the environment.

According to some embodiments, the assessment can, for example, be performed (through modeling) of the acoustic quantities required to calculate the loudspeaker's radiation impedance in the room. In contrast, previous methods relied on measuring the necessary parameters.

In some embodiments, a principle is provided for estimating radiation resistance or at least sound pressure and velocity, which has advantages over the prior art when used for specific classes of playback devices.

Some embodiments use one or more modeling approaches, and the need to use a specific microphone to measure sound pressure near the diffuser, as well as the need to use two microphones or other complex instruments or setups to measure velocity, are eliminated.

In some embodiments, the microphones may not be positioned directly in front of the diaphragm, for example. For example, the microphones may be positioned further than a few centimeters from the diaphragm.

In contrast to the prior art, some of the embodiments require evaluating the sound pressure at only one point.

Some of the embodiments may, for example, not require an accelerometer, and some of the embodiments may, for example, not require moving the microphone and may, for example, not require it to be placed near the membrane.

The details and principles of specific embodiments of the present invention are described below.

Let us first look at the details of calculating the radiation impedance and calculating the radiation resistance.

Radiation impedance is determined by the sound pressure ratio on the converter to the normal speed of the converter , as follows:

Where - constant associated with the area of the transducer membrane.

Fig. 3 shows an example loudspeaker with three different measurement positions (sound pressure). Among other things, Fig. 3 shows a measurement at two points And , Where And , located close in front of the loudspeaker membrane, correspond to two microphones/two measurement positions.

In other embodiments not shown in Fig. 3, two or more microphones are used, where one microphone is located inside the speaker housing. The accelerometer is located on the speaker diaphragm.

According to the same Fig. 3, the sound pressure on the surface of the transducer is set (approximately), as indicated in Fig. 3, by the sound pressure , measured in position , or sound pressure , measured in position , or average values And . Approximate normal speed can be calculated from sound pressure , measured in position , and sound pressure , measured in position , using the formula

Where - angular frequency, - density of the medium, - imaginary unit, and - axial distance from the center of the transducer membrane (in particular, - axial distance in position from the center of the converter membrane; - axial distance in position from the center of the transducer membrane).

Radiation impedance calculated according to

Thus, the acoustic quantities that can be estimated, for example, to calculate the (acoustic) impedance of a loudspeaker's radiation in a closed room are, for example, the axial velocity, , loudspeaker transducer and acoustic/sound pressure, , on the surface of the converter.

In some embodiments, the current through the loudspeaker transducer coil and the acoustic/sound pressure at a single point outside the loudspeaker enclosure are measured and used as input to estimate And Here, "outside the loudspeaker enclosure" may, for example, refer to a microphone that is preferably located in a known and fixed position on the loudspeaker enclosure or very close to it, allowing the known transducer properties and position to be used in the modeling.

The transducer velocity and sound pressure are not measured directly near the transducer. Instead, these values are estimated/approximated. A lumped electromechanical model is used to estimate the velocity.

An acoustic model is used to estimate the pressure.

Acoustic models can be built, for example, on wave methods, in particular FEM (finite element method), FDM (finite difference method), BEM (boundary element method) or, in the simplest case, only on the (rough) assumption of a spherical wave model.

For example, sound pressure can be modeled based on distance (e.g. radius ) from the membrane, for example, on the base

, (4)

where k is the wave number, and - source signal; or based on

(5)

where k is the wave number, - source signal, and - a term that takes into account, for example, the geometric distribution, the directivity of the transducers, and the room acoustics, which influence the attenuation characteristics. For example, .

In other words, in some of the embodiments, the measured current through the loudspeaker transducer coil and/or the acoustic/sound pressure at a single point may, for example, be used as input to an electromechanical model and/or an acoustic model, respectively, to obtain approximate/estimated values and/or , respectively.

Some models or methods used to estimate the estimated velocity may introduce errors that affect the estimated phase of the estimated velocity. To avoid introducing such errors, possible solutions include choosing more detailed models or more accurate numerical methods.

However, according to an embodiment, this problem can, for example, be advantageously avoided by assuming that the phases of the particle velocity and the acoustic pressure at the transducer are related, for example according to the continuity of the pulse:

(6)

Where - density of the medium.

According to an embodiment, the phase of the velocity can, for example, be estimated from the phase of the estimated pressure.

In a specific embodiment, in addition to the above, the estimated pressure may, for example, be used to further refine the estimated velocity, such that the estimated velocity depends not only on the measured current, but may, for example, also depend on information obtained from the estimated pressure. This yields refined estimates of the estimated radiation impedance and/or radiation resistance.

Fig. 4 depicts a high-level illustration of an embodiment.

The RS block is a device for measuring the current from the amplifier/current through the converter coil.

This can be achieved by measuring the voltage drop across a resistor, such as a shunt resistor.

When switch 410 is closed, the current measured by the RS unit is fed to the evaluation unit to estimate the radiation impedance or radiation resistance. When switch 410 is open, the measured current is not fed to the evaluation unit, and no evaluation of the radiation impedance or radiation resistance occurs.

TF is the transport path/transfer function from membrane S1 to microphone _m3 (see Fig. 3), which is modeled to obtain an estimate of the sound pressure in front of S1.

At the evaluation unit, the measured current and measured sound pressure are fed to the electromechanical model and the acoustic model to obtain estimates. And , respectively. On this basis, the radiation impedance or radiation resistance is calculated to perform global frequency correction based on a comparison with a theoretical reference curve or a given (reference) curve.

Fig. 5 shows some illustrative real world results of estimated radiation resistances for a particular loudspeaker at different positions in the same room, relative to the theoretical radiation resistance (target radiation resistance) according to embodiments.

Instead of the theoretical radiation impedance curve, one can, for example, specify any other reference curve, based on which one can, for example, calculate the desired frequency corrector (EQ) settings.

EQ, which may, for example, be used to compensate for room effects, may, for example, be based on a comparison of the estimated radiation impedance, for example, with the theoretical radiation impedance; or on a comparison of the estimated radiation resistance, for example, with the theoretical radiation resistance.

In some embodiments, smoothed versions of the estimated radiation resistance may, for example, be used to calculate filter compensation curves.

In a particular embodiment, the reference radiation resistance curve can, for example, be selected to perform global frequency correction by comparing the estimated radiation resistance with a target curve, which can be either specified (e.g., modeled) or theoretical. For example, the free-field radiation resistance formula can be used for this purpose, which can be specified, for example, as:

Where is the area of the loudspeaker membrane, and c is the speed of sound.

Fig. 6 shows a real-world example of a radiation resistance estimate compared to a free-field reference curve, and the calculated global frequency correction filter, for a loudspeaker located in a room corner.

Initial raw filter prototype for global frequency correction it can be calculated, for example, according to:

For example, a smoothed version this filtration curve can, for example, be used to calculate the final compensation filter, which can be obtained, for example, by anti-aliasing methods, such as using octave-band anti-aliasing. A smoothed version of the filter for a specific example is also shown in Fig. 6, where anti-aliasing was applied in a 1-octave band.

According to an embodiment, the frequency resolution can, for example, be selected and can, for example, be left unchanged during the calculation of the EQ (frequency correction) filter.

In another embodiment, to accommodate a given number of FIR filter taps, interpolation may, for example, be applied to the anti-aliasing filter, resulting in a reduction in frequency resolution.

According to one embodiment, a frequency limiter can also be used, for example, to limit the frequency correction to a specified frequency range. Frequency limiting can be implemented, according to one embodiment, for example, by applying a bandpass filter to the EQ filter's amplitude-frequency response.

Here, Fig. 6 shows the amplitude-frequency response of the global frequency correction filter after interpolation (number of filter taps: N = 4096) according to a specific example and further shows the band limitation (40 Hz ↔ 500 Hz) , which can, for example, be applied in a specific example.

Phase response of an FIR filter can, for example, be obtained by calculating the cepstrum for the implementation of the minimum phase version. FIR filter taps can, for example, be calculated using the inverse fast Fourier transform (IFFT), for example, according to:

In an additional embodiment, EQ shaping may be performed differently than the EQ shaping described above. This additional embodiment is particularly advantageous if the radiation impedance assessment in a particular room reveals specific problematic frequencies in the low-frequency region that are prominent, often referred to as dominant modes. Such dominant modes may arise due to unfavorable room size combinations that overemphasize specific frequencies, and/or if the loudspeaker is positioned in a way that excites specific room modes.

Since such excitation of specific room modes results in audible ringing/resonance/excessively long decay of specific frequency regions that can adversely affect auditory perception, it is preferable to specifically take care to attenuate these modal effects.

As an example, Fig. 7 depicts a high-resolution display of a raw filter prototype according to an embodiment. To better identify a particular modal problem, in this case, the reciprocal of the initial raw filter prototype, for example, given as:

indicates the excess relative sound power compared to the reference curve, which is displayed on a logarithmic scale.

According to the graph in Fig. 7, the described modal behavior can be clearly identified in the region around 57 Hz (indicated by the red circle). To cope with this modal behavior, high-Q filters are usually required.

One example of how such frequency correction of modal behavior might be accomplished is, for example, to apply a smoother global EQ as described above in the first stage, and then apply a specific high-Q modal EQ to correct specific peaks that were identified in the high frequency resolution analysis.

In another embodiment, the above-mentioned modal EQ can be applied using a single loudspeaker to compensate for modal effects.

Multiple loudspeakers can be used to compensate for low frequency modal effects in rooms.

The first loudspeaker and at least one additional loudspeaker are located in the room, and the modal behavior is controlled by sound arriving at the at least one additional loudspeaker.

The method for estimating the radiation impedance described herein allows for the method to be preferably applied using a plurality of loudspeakers, since the necessary identification of problematic frequency ranges to be corrected can be carried out, suitable additional loudspeakers applicable for compensating for the detected problematic frequency ranges can be automatically identified and selected, and the result of applying the compensation method can be continuously controlled.

Some of the embodiments are implemented in such a way that they are capable of implementing at least one of the above-described methods of generating a frequency equalizer/determining a frequency equalizer.

Additional embodiments are implemented such that they are capable of implementing more than one of the above-described methods for generating a frequency equalizer/determining a frequency equalizer, and selecting one of the methods for generating a frequency equalizer/determining a frequency equalizer. For example, one of the methods for generating a frequency equalizer/determining a frequency equalizer may be selected depending on the environment in which the device is used. For example, one of the methods for generating a frequency equalizer/determining a frequency equalizer is selected that is most suitable for the specific environment in which the device is used.

Fig. 8 demonstrates the use of models to estimate parameters according to an embodiment.

In the following, the evaluation of the speed of the converter according to some of the embodiments is described.

After measuring the current using, for example, the voltage drop across a shunt resistor, the speaker model description is used to estimate the normal speed of the transducer.

According to an embodiment, the speed may, for example, be determined by finding model parameters that minimize the error between the measured and modeled currents.

Various loudspeaker model descriptions exist. The evaluation process is described below using one illustrative, specific model. This model may, for example, be valid only at low frequencies, but for this application, this is sufficient, since in specific embodiments, only low-frequency performance may be subject to correction. In other embodiments, other models could be used similarly.

An electromechanical model of the parameters (e.g., linear, e.g., lumped) of a loudspeaker transducer, used here as an example, is shown in Fig. 9.

Fig. 9 shows a model of parameters (e.g., linear, e.g., lumped) according to an embodiment.

The elements on the electrical side (left side of the diagram in Fig. 9) are the exciting voltage , electrical resistance , inductance coils and the product of the power coefficient and speed cone.

The elements on the mechanical side (right side of the diagram in Fig. 9) are the product and current , mechanical mass , full hardness and mechanical resistance .

The following two related equations mathematically describe the model:

And

where acceleration is defined as

Equations (11) and (12) can be written in state space representation:

where is the designation represents the first derivative with respect to time. x denotes the axial displacement of the loudspeaker membrane of the said loudspeaker.

The system of equations (14) can be solved, for example, by an appropriate numerical method (for example, an iterative method), for example, the fourth-order Runge-Kutta method.

In another embodiment, the (common) excitation signal, , is used to excite the model. Initial hypotheses are made for the unknown parameters, The system is solved, and the predicted current is compared with the measured current. To predict the linear parameters of the converter, the minimization problem is solved using a cost function.

Where >- a vector of unknown parameters. The final solution provides the predicted speed,Then the normal speed can be given, for example, as, Where - measured current,- simulated current. Linear parameters are predicted by minimizing the difference between the measured and simulated currents. Linear parameters do not change the input audio channel. Other implementations use different cost functions.

To estimate the sound pressure at the transducer, the wave equation is solved to find the free-field transfer function (TF) from the center of the transducer to the measurement position (see Fig. 4) Using this transfer function, the sound pressure at the source can be predicted from the measured sound pressure.

Various principles are available for acoustic modeling or simulation to generate a model of, for example, a loudspeaker and a transfer function.

For example, a loudspeaker can be modeled in a free field, assuming that all surfaces of the loudspeaker enclosure are acoustically rigid. (More detailed models will be possible, including room boundary conditions and accurate modeling of the loudspeaker surfaces and material properties.)

Also, specific situations that can be found in practical scenarios (e.g., placement of a loudspeaker on a table, on a shelf, near one, two, three boundary surfaces (e.g., near a wall, in a corner, ...) can, for example, be modeled and selected in an actual listening environment (detection/selection either automatically or by the user). Also, in some embodiments, modeling of the entire room is used, for example, based on additional input data. (As an example, Fig. 13 depicts a loudspeaker on a surface/table).

A single sound pressure can, for example, be applied to a transducer for a range of significant input frequencies. The solution in position is restored. From this solution, the complex transfer function can be calculated, for example, as follows

Where - the sound pressure applied to the transducer, and - sound pressure adopted in position Then the required sound pressure is set. .

In some embodiments, the above-described principles are not limited to the use of a single microphone. Instead, for example, microphone arrays with a variable number of microphones in different configurations (e.g., a linear array, a circular array located on different surfaces of the loudspeaker housing) may be used; see, for example, the embodiments illustrated in Fig. 12, Fig. 14, Fig. 15.

Some embodiments may, for example, utilize multiple recordings from different microphones. One could, for example, select the one that provides the best recording in the current situation. One could, for example, calculate the average of all recorded signals to achieve an overall better estimate than using a single recording.

In some embodiments, the microphone may be, for example, an external microphone (e.g., a mobile phone microphone). For example, the exact model and position during the measurement may, for example, be known and may, for example, be included in the modeling.

By exciting the individual transducers (diaphragms) of a multi-transducer loudspeaker separately with a test signal, more information can be collected, for example about the room (e.g. changing modal behavior).

For example, a parametric model (e.g., a lumped parameter model) can be used, and the system can be continuously monitored. For example, it can be checked to see if anything in the system's setup or behavior changes over time. For example, it can detect changes in position or environment.

According to another embodiment, the estimated speed information (e.g., converter speed) may, for example, be estimated once, for example, at the system design stage.

For example, according to another embodiment, the estimated speed information may, for example, be stored in the device 100.

Such an embodiment may, for example, rely on the assumption that the profile of the magnitude of the estimated speed of the converter (e.g., the frequency-dependent magnitude of the speed) does not undergo significant change between rooms, or at different positions in the room.

According to an embodiment, the design-stage evaluation may, for example, be carried out by evaluating in a laboratory environment the magnitude of the velocity in the full/significant (audio) frequency range for a specific loudspeaker or transducer, for example, in response to an applied unit voltage or, for example, a known voltage.

The profile of the estimated speed value can then, for example, be stored in a lookup table.

Thus, according to an embodiment, the estimated speed information may, for example, be stored in a lookup table that is stored in the device 100. The estimation unit 110 may, for example, be configured to output the estimated speed information from the lookup table.

In a linear audio system, a change in the excitation voltage level (e.g., the input audio signal level) will result in a linearly proportional change in the transducer speed.

According to an embodiment, the estimator 110 may, for example, be configured to output the estimated speed information from a lookup table using the excitation voltage level as an input to the lookup table.

Thus, according to an embodiment, during the run, the magnitude of the converter speed can be determined from the excitation voltage (and, possibly, the conversion factor) and the values stored in said lookup table, while the phase of the speed can be estimated from the estimated pressure information, using the continuity of the pulse.

According to an embodiment, a kind of 'health check' of the system/converters can be performed, for example. In some embodiments, it is possible, for example, to monitor the change in converter parameters over time.

A device is provided that includes an evaluation unit 110.

The evaluation unit 110 is configured to evaluate the first radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as the first estimated radiation resistance before the first time; or is configured to evaluate the first radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as the first estimated radiation impedance before the first time, wherein said first estimated radiation impedance of said transducer contains estimated information about the first radiation resistance of said transducer.

In order to estimate the first estimated radiation resistance or the first estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit 110 is configured to estimate the first estimated radiation resistance or the first estimated radiation impedance depending on the information of the first estimated sound pressure, indicating the estimate of the sound pressure on said transducer of said loudspeaker before the first moment in time, and depending on the information of the first estimated speed, indicating the estimate of the first speed of the transducer of said transducer of said loudspeaker before the first moment in time.

In addition, the evaluation unit 110 is configured to evaluate the second radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a second estimated radiation resistance after a second time; or is configured to evaluate the second radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a second estimated radiation impedance after a second time, wherein said second estimated radiation impedance of said transducer contains estimated information about the second radiation resistance of said transducer.

In order to estimate the second estimated radiation resistance or the second estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit 110 is configured to estimate the second estimated radiation resistance or the second estimated radiation impedance depending on the information of the second estimated sound pressure, indicating the estimate of the sound pressure on said transducer of said loudspeaker after the second moment in time, and depending on the information of the second estimated speed, indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker after the second moment in time.

In addition, the evaluation unit 110 is configured to determine and output whether the device is in the first state or in the second state depending on the difference in radiation resistances indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance, or depending on the difference in radiation impedances indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance.

The second state indicates that the device is not functioning properly or that the device has changed location. The first state indicates that the device is functioning properly and that the device has not changed location.

According to an embodiment, the estimating unit 110 may, for example, be configured to estimate the first estimated sound pressure information depending on the captured first sound pressure information recorded by one or more microphones before the first time, and the estimating unit 110 may, for example, be configured to estimate the second estimated sound pressure information depending on the captured second sound pressure information recorded by one or more microphones after the second time. And/or the estimating unit 110 may, for example, be configured to estimate the first estimated speed information depending on the first current through the transducer coil of the loudspeaker of said transducer of said loudspeaker before the first time, and the estimating unit 110 may, for example, be configured to estimate the second estimated speed information depending on the second current through the transducer coil of the loudspeaker of said transducer of said loudspeaker after the second time.

According to an embodiment, the evaluation unit 110 may, for example, be configured to determine a difference in radiation resistances by determining a difference value indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance; or configured to determine a difference in radiation impedances by determining a difference value indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance. The evaluation unit 110 may, for example, be configured to determine that the device is in the second state if the difference value is greater than a threshold value. Furthermore, the evaluation unit 110 may, for example, be configured to determine that the device is in the first state if the difference value is less than or equal to the threshold value.

According to an embodiment, additionally another means, for example, one or more gyroscopes, or other information collected from the pressure measurement, may, for example, also be used as an indication that the device has moved.

In some embodiments, the global EQ estimate from two (or more) different (spatially separated) loudspeakers may, for example, be used to obtain a better estimate of the global EQ/room behavior.

In a specific embodiment, information obtained from multiple loudspeakers can, for example, be used to perform modal frequency correction. Based on the actual positions of multiple loudspeakers and the estimated modal behavior, it is possible to, for example, check whether improved reproduction can be achieved in the modal frequency range and/or whether one or more loudspeakers can be used to compensate for the modal effects of other loudspeaker/room combinations.

In some embodiments, the models used to estimate the sound pressure on the diaphragm may, for example, also include environment models to obtain better estimates. These environments may, for example, be subsequently set by the user. Or, these environments may, for example, be detected automatically. For example, if a loudspeaker is placed on a flat, hard surface (e.g., a table), it will behave differently than if it is placed on a bookshelf.

Fig. 10 shows a side view of an alternative arrangement of a loudspeaker with transducers/transducers on four sides according to an embodiment.

Fig. 11 shows a top view of an alternative arrangement of a loudspeaker with transducers/transducers on four sides according to an embodiment.

Fig. 12 shows an alternative arrangement of a multi-microphone bar-type loudspeaker according to an embodiment.

Fig. 13 shows an example of a loudspeaker located on a surface (e.g., a table) according to an embodiment.

Fig. 14 shows a top view of the loudspeaker showing possible positions for one or multiple microphones according to an embodiment.

Fig. 15 shows a side view of the loudspeaker showing possible positions for one or multiple microphones according to an embodiment.

Fig. 16 shows another side view of the loudspeaker showing possible positions for one or multiple microphones according to another embodiment.

In some embodiments, it may be useful to provide additional structures on the actual speaker housing, such as means for dispersing the sound of certain speakers, such as upward-firing speakers, by means of diffusers, distributors, conical structures, diffusing cones, waveguides, etc., or other forms for distributing sound in specific directions, such as horizontally or in specific directions.

In such cases, microphones may preferably be positioned on top of such structures as shown in Fig. 16.

Next, we will consider additional implementation options.

In some embodiments, the loudspeaker's performance is controlled in-room. The required control parameters (rather than being measured directly) are estimated based on measurements of easily obtainable parameters. These measured parameters serve as input parameters for at least one model that approximates the required control parameters.

According to an embodiment, one of the models is an acoustic model, for example, an acoustic model for approximating the sound pressure on a membrane.

According to an embodiment, one of the models is a simple plane wave approximation.

According to an embodiment, one of the models is a (detailed) wavelet method, such as the finite element method. According to an embodiment, one can, for example, use modeling of one or more properties of a specific loudspeaker.

According to an embodiment, the sound pressure prediction model is a (simple) spherical wave approximation. For example, if the distance between the measurement point in front of the woofer and the actual measurement point, say, a few tens of centimeters from the woofer, is known, then the sound pressure at the woofer, for example, in the low-frequency region, can be calculated/approximated from the distant measurement. The calculated approximation assumes that sound propagates as a spherical wave and simply takes into account the distance of the measurement point from the woofer. This approximation may be referred to as a "spherical wave approximation."

According to an embodiment, one of the models may be, for example, an electromechanical model, for example for approximating speed based on a current measurement.

According to one embodiment, one of the easily obtained parameters is a sound pressure measurement, which, for example, does not need to be captured near the membrane. For example, one or more microphones that measure the sound pressure could be built-in microphones of a smart speaker, or, for example, a playback system that already includes microphones for interaction with, for example, a voice assistant.

According to an embodiment, each transducer/loudspeaker transducer, which comprises a plurality of transducers/transducers, can, for example, be used individually to select the best suitable transducer in a given situation, or can, for example, be used to calculate the average or all transducers used to improve the result.

In one embodiment, a specific test signal may, for example, be used to calibrate the system. In another embodiment, material from a program being played (e.g., music) may instead be used to calibrate the system.

According to an embodiment, a specific phrase of a voice assistant may, for example, be used as a test signal instead of a specific test signal.

According to an embodiment, the calibration may, for example, be performed at a specific point in time (which may, for example, be initiated by the user, such as after moving the loudspeaker).

According to another embodiment, instead of performing calibration at a specific point in time, the system may, for example, continuously adapt to the environment.

According to an embodiment, the system may, for example, perform a new calibration only when a change in the installation environment/position is detected.

According to an embodiment, one or more loudspeakers may be, for example, a first loudspeaker. One or more transducers of the first loudspeaker may be, for example, a first transducer of the first loudspeaker. The evaluation unit 110 may, for example, be configured to evaluate the radiation resistance of the first transducer of the first loudspeaker as an estimated radiation resistance; or may, for example, be configured to evaluate the radiation impedance of the first transducer of the first loudspeaker as an estimated radiation impedance.

According to an embodiment, one or more input audio channels may, for example, represent a first input channel, and one or more output audio channels may, for example, represent a first output channel for a first transducer. Processing unit 120 may, for example, be configured to determine a first filter for the first transducer depending on the estimated radiation resistance or depending on the estimated radiation impedance. Furthermore, processing unit 120 may, for example, be configured to apply the first filter for the first transducer on the first input channel to obtain a first output channel for the first transducer.

According to an embodiment, the processing unit 120 may, for example, be configured to determine an additional filter for each additional transducer of one or more additional transducers of each additional loudspeaker of one or more additional loudspeakers depending on the first filter for the first transducer. The processing unit 120 may, for example, be configured to apply the additional filter of each additional transducer of one or more additional transducers of each additional loudspeaker of one or more additional loudspeakers to an additional input signal of one or more additional input signals to obtain an additional output signal of one or more additional output signals for said additional transducer.

According to an embodiment, the processing unit 120 may, for example, be configured to determine a global frequency correction filter by determining an additional filter for at least one of the one or more additional transducers from at least one of the one or more additional loudspeakers, wherein the processing unit (120) may, for example, be configured to use the initial raw filter curve of the first transducer for the one or more additional transducers to obtain a smoothed filter curve for at least one of the one or more additional transducers.

According to an embodiment, the processing unit 120 may, for example, be configured to determine an additional filter for at least one of the one or more additional transducers from at least one of the one or more additional loudspeakers using a frequency limiter to limit the frequency correction to a frequency range for at least one of the one or more additional transducers.

According to an embodiment, the estimating unit 110 may, for example, be configured to evaluate two or more radiation resistances or two or more radiation impedances for two or more transducers of one or more loudspeakers. The processing unit 120 may, for example, be configured to determine two or more raw filter curves for two or more transducers depending on two or more radiation resistances or two or more radiation impedances. Furthermore, the processing unit 120 may, for example, be configured to determine a weighted-average filter curve by determining a weighted average of two or more raw filter curves, or configured to determine a smoothed weighted-average filter curve by determining a smoothed weighted average of two or more raw filter curves. In addition, the processing unit 120 may, for example, be configured to apply a weighted-average filtering curve or a smoothed weighted-average filtering curve, or a filtering curve derived from the weighted-average filtering curve or from the smoothed weighted-average filtering curve, to an input audio signal from one or more input audio signals to obtain an output audio signal from one or more output audio signals for another transducer other than the two or more transducers.

In some embodiments, the estimated radiation resistance or impedance of a single transducer may be used to calculate a global frequency correction filter for one or more additional transducers. This may be achieved using an initial, raw filter prototype. said single converter to one or more additional converters to obtain a smoothed version this filtration curve at a common or individual smoothing rate for each transducer, for example, using common or individual octave-band smoothing. To limit the frequency correction to a frequency range specified either generally or individually for one or more transducers, a frequency limiter can also be used, for example. Frequency limiting can be implemented, according to an embodiment, for example, by applying a bandpass filter to the amplitude-frequency response of the equalization filter.

According to an embodiment, the weighted average and/or two or more transducers can also be used to calculate a global frequency correction filter for one or more transducers.

In another embodiment, an additional user-defined target equalization curve may also be applied to obtain a user-defined global equalization. Fig. 17 shows the amplitude-frequency response of the global equalization filter after applying an additional user-defined target equalization curve to the initially obtained according to a specific example, using 1-octave band smoothing and band limiting (40 Hz ↔ 500 Hz).

In the following, additional embodiments for estimating radiation impedance and/or estimating radiation resistance are described.

According to an embodiment, the processing unit 120 may, for example, be configured to determine a filter for at least one of the one or more transducers of at least one of the one or more loudspeakers depending on a user-specified target frequency correction curve.

According to an embodiment, the estimator 110 may, for example, be configured to evaluate the estimated sound pressure information and/or the estimated speed information as a function of the sound pressure at the microphone from one or more microphones.

According to an embodiment, one or more microphones are remote from said loudspeaker.

According to an embodiment, the estimator 110 may, for example, be configured to evaluate the estimated sound pressure information as a function of the sound pressure at said microphone from one or more microphones.

According to an embodiment, the one or more microphones represent exactly one microphone.

According to an embodiment, the estimating unit 110 may, for example, be configured to evaluate the estimated speed information depending on the sound pressure at said microphone.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated speed information independently of the current measurement, and independently of the voltage measurement, and independently of the displacement signal measurement, and independently of the acceleration signal measurement, and independently of the movement of said microphone to obtain the second measurement.

According to an embodiment, the estimating unit 110 may, for example, be configured to evaluate the estimated speed information depending on the estimated sound pressure information, which indicates the estimated sound pressure at said transducer of said loudspeaker.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated sound pressure information depending on the sound pressure at said microphone.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated sound pressure information further depending on the transfer function , where the transfer function differs from , Where denotes the angular frequency.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated sound pressure information according to:

Where - estimated sound pressure information that indicates an estimated sound pressure at said transducer of said loudspeaker, and - sound pressure at the mentioned microphone.

According to an embodiment, the transfer function may be, for example, a free-field transfer function.

According to an embodiment, the transfer function may, for example, depend on the surface on which the device 100 is located. Or the device 100 is located in an environment, and the transfer function may, for example, depend on one or more surfaces of the environment.

According to an embodiment, the evaluation unit 110 may, for example, be configured to evaluate the estimated sound pressure information as

Where - estimated sound pressure information which indicates the estimated sound pressure at said transducer of said loudspeaker, - the sound pressure at the said microphone, and denotes the angular frequency.

According to an embodiment, the estimating unit 110 may, for example, be configured to estimate the magnitude of the estimated speed information as the estimated magnitude of the estimated speed information, and/or the estimating unit 110 may, for example, be configured to estimate the phase of the estimated speed information as the estimated phase of the estimated speed information. The estimating unit 110 may, for example, be configured to estimate the estimated speed information depending on the estimated magnitude of the estimated speed information and/or depending on the estimated phase of the estimated speed information.

According to an embodiment, the estimator 110 may, for example, be configured to evaluate the estimated speed information depending on

Where denotes the estimated speed information, denotes the estimated value, denotes the estimated phase, and where i denotes an imaginary number.

According to an embodiment, the estimating unit 110 may, for example, be configured to estimate the estimated magnitude and/or the estimated phase depending on the acceleration or the estimated acceleration on the surface of said transducer of said loudspeaker.

According to an embodiment, the evaluation unit may, for example, be configured to evaluate the estimated value of V _abs depending on

; and/or

where the evaluation unit may, for example, be configured to evaluate the phase V _ang of the evaluation depending on

;

where A _e indicates the acceleration or estimated acceleration, where i denotes an imaginary number, and denotes the angular frequency.

According to an embodiment, the estimator 110 may, for example, be configured to estimate the estimated acceleration by performing a function minimization method or a function maximization method depending on the function for obtaining the estimated acceleration and depending on the estimate of the sound pressure on said transducer of said loudspeaker.

According to an embodiment, the function minimization method may be, for example, the Nelder-Mead simplex method.

According to an embodiment, the estimator 110 may, for example, be configured to estimate the mass as the estimated mass, the stiffness as the estimated stiffness, and the resistance as the estimated resistance. The estimator 110 may, for example, be configured to estimate the estimated acceleration as a function of the estimated mass, the estimated stiffness, and the estimated resistance.

According to an embodiment, to estimate the estimated acceleration, the estimator 110 may, for example, be configured to minimize

where M denotes mass, K denotes stiffness, R denotes resistance, and || || ₂ denotes the Euclidean norm, and

where P _s indicates the estimated sound pressure at said transducer of said loudspeaker, and A _e (M, K,R) denotes the function for obtaining the estimated acceleration.

According to an embodiment, the function A _e (M, K, R) for obtaining the estimated acceleration can, for example, be defined according to

Where denotes the maximum absolute value of the sound pressure at said transducer of said loudspeaker, where i denotes an imaginary number, and denotes the angular frequency.

According to an embodiment, to estimate the estimated phase, the estimator 110 may, for example, be configured to minimize

where P _ff denotes the pre-measured or pre-calculated pressure, V _ff denotes the pre-measured or pre-calculated velocity, M denotes the mass, K denotes the stiffness, R denotes the resistance, and || || ₂ denotes the Euclidean norm.

According to an embodiment, to estimate the estimated radiation impedance one of one or more transducers of one loudspeaker of one or more loudspeakers, the evaluation unit 110 may, for example, be configured to evaluate the estimated radiation impedance by evaluating the information of the estimated sound pressure P _s , by evaluating two speed estimates , as information about the estimated velocity, and by estimating the estimated radiation impedance depending on

where mean denotes a function that determines the average of two parameters, where And - weighting factors that depend on the proximity of the microphone from one or more microphones to the said loudspeaker.

Some embodiments involve measuring or estimating the power emitted into the room by the sound source (in this case, a loudspeaker) to enable digital control of the generated acoustic field. For this purpose, it is sufficient to measure or estimate the radiation impedance, which indicates the power emitted into the room. Radiation impedance is determined by the ratio of the sound pressure on the transducer, , to the normal speed of the converter, , as follows:

Where - a constant associated with the area of the transducer membrane, and - angular frequency.

In some embodiments, a single pressure signal, for example, obtained through a single microphone positioned outside the sound source, may be used to estimate pressure and velocity. Of course, more microphones may be used. However, in these embodiments, a single microphone is sufficient. Thus, in these embodiments, radiation impedance and/or radiation resistance can be estimated based on a single measured signal.

Fig. 18 shows an evaluation of the radiation impedance and/or resistance according to another embodiment, depending on one microphone.

Fig. 19 shows an estimation of the radiation impedance and/or resistance according to a further embodiment, depending on one pressure measurement from one microphone. Fig. 19 is a modified version of Fig. 4.

The evaluation method is described below.

The pressure assessment is described below.

The acoustic pressure generated by a source in a room is measured near the source. The source's transfer function is used to estimate the pressure at the source:

Where - estimated pressure at the source, - the measured pressure at the microphone, and - transfer function. Just for clarity: the relationship between the formula and Fig. 19 is as follows: corresponds to the estimated pressure at source S ₁ . corresponds to the pressure measured on/with a microphone m ₃ . Transfer function corresponds to the TF indicated by the arrow. The transfer function is a complex function in the frequency domain.

The transfer function can be selected to reflect the microphone and loudspeaker setup. For example, if the microphone is positioned directly in front of the loudspeaker transducer, the transfer function can take a value of 1 for each frequency, such as .

As a second example, the free-field transfer function can be used. It can be obtained by measurement in an anechoic chamber, by simulation using a wave modeling method, or by calculation using a mathematical model.

As a third example, the transfer function may include effects such as placing the device on different surfaces, such as the floor or a table.

As a fourth example, the transfer function may include the effects of multiple adjacent surfaces, such as when a device is placed on a shelf or in a room.

In a simplified version of the implementation, one can assume that even when the microphone is not positioned in front of the transducer. This bypasses the pressure estimation step, thus providing a more efficient, though perhaps less accurate, estimate.

The speed assessment is described below.

Velocity estimation is based on measured acoustic pressure. The estimation consists of two stages: velocity magnitude estimation and velocity phase estimation.

The estimation of the quantity is described below.

First of all, we note that the acoustic pressure generated by the source is proportional to the acceleration at the surface of the source, which can be seen in Fig. 20.

Fig. 20 shows a comparison of the measured normalized pressure and the measured normalized acceleration.

Under free field conditions, if the magnitude of the source pressure is divided by the magnitude of the surface acceleration, the resulting function is will be an approximately constant function of frequency. In a confined space, such as a room, will depend on the resonances of the room, but it will still be possible to find a constant that passes through the function, which can be seen in Fig. 21 below.

Fig. 21 shows the average normalized pressure-acceleration ratio when measured indoors (indoors).

Since there is a relationship between velocity and surface acceleration, using an acceleration estimate will yield an estimate of velocity. To estimate acceleration, one could use, for example, a linear model of a loudspeaker, as follows:

Where - source function, - weight, - rigidity, and - resistance. Acceleration, , is equal to the derivative of the velocity with respect to time, , which, in turn, is equal to the derivative of the displacement, by time:

Where denotes the axial displacement of the loudspeaker membrane. In the frequency domain, we obtain:

Using the model given in equation (19) in the frequency domain, the acceleration can be estimated

Where - the maximum absolute value of the estimated source pressure, finding the complex parameters, , , And , which minimize the cost function

Where - estimated source pressure normalized by estimated surface acceleration.

Equation (23) is solved using a function minimization method, such as the Nelder-Mead simplex method [1], [2]. The solution to the minimization problem provides an estimated acceleration, from which an estimated velocity can be calculated using equation (21).

Note that since the shape of the velocity value does not change significantly from room to room, a lookup table can also be used to estimate the velocity value.

The phase evaluation is described below.

Velocity phase estimation is based on the phase angle of the ratio of a pre-measured or pre-calculated pressure to a pre-measured or pre-calculated velocity. These quantities can be measured or calculated based on the desired device installation conditions, such as in a free field or near a reflective surface.

As an example, the phase angle of the pressure relationship is shown here, , in a free field to speed, , in a free field. The required free-field quantities are either measured in an anechoic chamber, simulated using a wave modeling method, or calculated using a mathematical model.

The model presented in equation (22) is used to find the phase velocity. The source function for the model, , includes the measured pressure phase shifted by 90 degrees. Complex parameters that minimize the cost function

are used to obtain an estimate of the phase velocity. Equation (25) is solved using a function minimization method, for example, the Nelder-Mead simplex method [1, 2].

A comparison of the free field angle and indoor angle profiles is shown in Fig. 22.

Fig. 22 shows a comparison of the free-field and indoor radiation impedance phase as a function of frequency.

In practice, when the microphone is located further from the loudspeaker, it has been found useful to perform this evaluation twice; once when the source term is a function of the unwrapped phase of the estimated source pressure

and the second time with a smoothed version of the expanded pressure phase

Where - a function fitted to the pressure phase angle. In the expression for the function , subscript indicates the phase angle located at -m peak (where peak indicates, for example, either local maxima or local minima) of the phase gradient, (shown in Fig. 23, which demonstrates the pressure phase angle gradient). The function is a piecewise interpolation function of any order, for example, cubic.

Ultimately, the fitted function is obtained, for example, by interpreting the phase angles located at the frequencies where the phase gradient peaks occur. However, other (polynomial) fitting procedures can also be used. These estimates are used in the next stage of estimating the radiation impedance.

The phase velocity is estimated according to

Thus, the estimated speed can, for example, be determined as follows:

The complex velocity estimate can be given, for example, in the form:

By estimating the pressure and velocity of the source, the radiation impedance can be calculated.

In a specific embodiment, two velocity estimates can be used, for example. In such an embodiment, two intermediate estimates of the radiation impedance are obtained from these estimates, which are then used to estimate the final radiation impedance.

Where And depend on the proximity of the microphone to the measured loudspeaker. Typically, both parameters are equal to one, , And , but they can be adjusted to improve the accuracy of the estimate.

The radiation resistance can, for example, be determined according to

According to embodiments, to apply global frequency correction, a set of filters is calculated to flatten the radiation resistance curve relative to a target curve. The choice of target curve will depend on the desired loudspeaker response. In this application, it is proposed to use a simulated free-field radiation resistance. The free-field radiation resistance can be measured in an anechoic chamber modeled using a wave modeling method or calculated using a mathematical model.

The free-field and indoor radiation resistances are compared in Figs. 24 through 28. It can be seen that the theoretical radiation resistance is represented by a straight line, while the simulated (or simulated) radiation resistance is represented by a curved line. The model takes into account the actual shape of the loudspeaker transducer, unlike the theoretical approximation; the model provides a more accurate description of the radiation resistance. The free-field radiation resistance can be used as a target curve for generating global frequency correction filters.

In a particular embodiment, the reference radiation resistance curve may, for example, be selected to perform a global frequency correction by comparing the estimated radiation resistance with a target curve, which may be, for example, modeled, measured or theoretical.

Gain equalization can be used to equalize the target curve and the estimated radiation resistance.

Such gain equalization can be achieved, for example, by obtaining an average level over a specific frequency range of the reference target curve and the estimated radiation resistance.

Fig. 24 shows a comparison of the free-field and room-radiation resistances for the first loudspeaker.

Fig. 25 shows a comparison of the radiation resistance in a free field and in a room for the second loudspeaker

Fig. 26 shows a comparison of the radiation resistance in a free field and in a room for the third loudspeaker

Fig. 27 shows a comparison of the radiation resistances in a free field and in a room for the fourth loudspeaker

Fig. 28 shows an overview of the evaluation process as described above, being a modification/update of Fig. 8.

Although some aspects have been described in the context of a device, it is clear that these aspects also represent a description of the corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method step also represent a description of the corresponding block, element, or feature of the corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such a device.

Depending on the implementation requirements, embodiments of the invention may be implemented using hardware or software, or at least partially using hardware or at least partially using software. Implementation may be accomplished using a digital storage medium, such as a floppy disk, DVD, Blu-ray, CD, ROM, PROM, EPROM, EEPROM, or flash memory, which stores electronically readable control signals that interact (or are capable of interacting) with a programmable computer system to implement the corresponding method. Thus, the digital storage medium may be machine-readable.

Some embodiments of the invention include a data transfer means having electronically readable control signals that are capable of interacting with a programmable computer system to perform one of the methods described herein.

In general, embodiments of the present invention may be implemented as a computer program product with a program code, wherein the program code is capable of executing one of the methods when the computer program product is executed on a computer. The program code may be stored, for example, on a machine-readable medium.

Other embodiments comprise a computer program for implementing one of the methods described herein, stored on a machine-readable medium.

In other words, an embodiment of the method according to the invention is thus a computer program having a program code for implementing one of the methods described herein when the computer program is executed on a computer.

Thus, a further embodiment of the methods according to the invention is a data carrier (or digital storage medium or machine-readable medium) on which a computer program for implementing one of the methods described herein is recorded. The data carrier, digital storage medium, or recording medium is typically tangible and/or permanent.

Thus, an additional embodiment of the method according to the invention is a data stream or signal sequence representing a computer program for implementing one of the methods described herein. The data stream or signal sequence may, for example, be configured to be transferable via a data connection, such as the Internet.

An additional embodiment comprises a processing means, such as a computer or a programmable logic device, configured to or adapted to perform one of the methods described herein.

An additional embodiment comprises a computer with a computer program installed thereon for implementing one of the methods described herein.

An additional embodiment according to the invention comprises a device or system configured to transfer (e.g., electronically or optically) a computer program for implementing one of the methods described herein to a receiver. The receiver may be, for example, a computer, a mobile device, a storage device, etc. The device or system may comprise, for example, a file server for transferring the computer program to the receiver.

In some embodiments, a programmable logic device (e.g., a field-programmable gate array) may be used to implement some or all of the functionality of the methods described herein. In some embodiments, the field-programmable gate array may interact with a microprocessor to implement one of the methods described herein. In general, the methods are preferably implemented by any hardware device.

The apparatus described herein may be implemented using a hardware device, or using a computer, or using a combination of a hardware device and a computer.

The methods described herein may be performed using a hardware device, or using a computer, or using a combination of a hardware device and a computer.

The embodiments described above are intended merely to illustrate the principles of the present invention. It should be understood that modifications and variations of the configurations and details described herein will be apparent to those skilled in the art. The intention, therefore, is to limit the invention only by the scope of the following claims, and not by the specific details presented through the description and explanation of the embodiments discussed herein.

Literature:

[1] Nelder, J. A. and Mead, R., A Simplex Method for Function Minimization, The Computer Journal , Volume 7, Issue 4, January 1965, pp. 308-313.

[2] Lagarias, J.C., Reeds, J.A., Wright, M.H., and Wright, P.E., Convergence Properties of the Nelder--Mead Simplex Method in Low Dimensions, SIAM Journal on Optimization , Volume 9, Number 1, December 1998, pp. 112-147.

Claims (289)

1. A device (100) for processing an input audio signal containing one or more input audio channels to obtain an output audio signal containing one or more output audio channels, wherein the device (100) comprises: an evaluation unit (110) configured to evaluate the radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation resistance; or configured to evaluate the radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation impedance, wherein said estimated radiation impedance of said transducer contains estimated information about the radiation resistance of said transducer, and a processing unit (120) configured to obtain one or more output audio channels by processing each input audio channel of the one or more input audio channels depending on the estimated radiation resistance or depending on the estimated radiation impedance of each of the one or more transducers of each of the one or more loudspeakers, wherein, for estimating the estimated radiation resistance or the estimated radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers, the estimating unit (110) is configured to estimate the estimated radiation resistance or the estimated radiation impedance using at least one of the estimated sound pressure information and the estimated speed information, wherein the estimated sound pressure information indicates an estimate of the sound pressure on said transducer of said loudspeaker instead of measuring the sound pressure directly on said transducer, and wherein the estimated speed information indicates an estimate of the speed of the transducer for said transducer of said loudspeaker instead of measuring the speed of the transducer directly on said transducer. 2. The device (100) according to item 1, in which, in order to estimate the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker, the evaluation unit (110) is configured to estimate the estimated radiation resistance or the estimated radiation impedance by evaluating estimated sound pressure information indicating an estimate of the sound pressure on said transducer of said loudspeaker, and/or by evaluating estimated speed information indicating an estimate of the speed of the transducer of said transducer of said loudspeaker. 3. The device (100) according to item 1 or 2, in which the evaluation unit (110) is configured to evaluate the estimated sound pressure information in such a way that the estimated sound pressure information is represented in the spectral domain, and/or the evaluation unit (110) is configured to evaluate the estimated speed information in such a way that the estimated speed information is represented in the spectral domain, and the evaluation unit (110) is configured to evaluate the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker in such a way that the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker is represented in the spectral domain. 4. The device (100) according to one of the previous points, in which the evaluation unit (110) is configured to evaluate the estimated sound pressure information and/or the estimated speed information depending on the sound pressure at the microphone from one or more microphones. 5. The device (100) according to item 4, in which one or more microphones are remote from said loudspeaker. 6. The device according to paragraph 4 or 5, in which the evaluation unit (110) is configured to evaluate the estimated sound pressure information depending on the sound pressure at said microphone from one or more microphones. 7. The device (100) according to any one of paragraphs 4-6, in which the evaluation unit (110) is configured to evaluate the information of the estimated sound pressure on said microphone. 8. The device (100) according to any one of paragraphs 4-7, in which the evaluation unit (110) is configured to evaluate the estimated speed information depending on the sound pressure at said microphone. 9. The device (100) according to clause 8, in which the evaluation unit (110) is configured to evaluate the estimated speed information regardless of the current measurement, and regardless of voltage measurement, and regardless of the measurement of the offset signal, and regardless of the acceleration signal measurement, and regardless of the movement of the said microphone to obtain the second dimension. 10. The device (100) according to item 8 or 9, in which the evaluation unit (110) is configured to evaluate the estimated speed information depending on the estimated sound pressure information, which indicates the estimated sound pressure on said transducer of said loudspeaker. 11. The device (100) according to item 10, in which the evaluation unit (110) is configured to evaluate the estimated sound pressure information depending on the sound pressure at said microphone. 12. The device (100) according to clause 11, in which the evaluation unit (110) is configured to evaluate the information of the estimated sound pressure additionally depending on the transfer function , where the transfer function differs from , Where denotes the angular frequency. 13. The device (100) according to item 12, in which the evaluation unit (110) is configured to evaluate the estimated sound pressure information according to: , Where - estimated sound pressure information that indicates an estimated sound pressure at said transducer of said loudspeaker; and - sound pressure at the mentioned microphone. 14. The device (100) according to item 12 or 13, in which the transfer function is the free-field transfer function. 15. The device (100) according to any one of paragraphs 12-14, in which the transfer function depends on the surface on which the device (100) is located, or the device (100) is located in an environment and the transfer function depends on one or more surfaces of the environment. 16. The device (100) according to item 11, in which the evaluation unit (110) is configured to evaluate the estimated sound pressure information as , Where - estimated sound pressure information which indicates the estimated sound pressure at said transducer of said loudspeaker; - the sound pressure at the said microphone; and denotes the angular frequency. 17. The device (100) according to any one of paragraphs 8-16, in which the evaluation unit (110) is configured to evaluate the magnitude of the estimated speed information as the estimated magnitude of the estimated speed information and/or the evaluation unit (110) is configured to evaluate the phase of the estimated speed information as the estimated phase of the estimated speed information, wherein the evaluation unit (110) is configured to evaluate the estimated speed information depending on the estimated value of the estimated speed information and/or depending on the estimated phase of the estimated speed information. 18. The device (100) according to clause 17, in which the evaluation unit (110) is configured to evaluate the estimated speed information depending on , Where denotes estimated speed information; denotes the estimated value; denotes the estimated phase; and where i denotes an imaginary number. 19. The device (100) according to item 17 or 18, in which the evaluation unit (110) is configured to evaluate the estimated magnitude and/or the estimated phase depending on the acceleration or the estimated acceleration on the surface of said transducer of said loudspeaker. 20. The device (100) according to clause 19, in which the evaluation unit is configured to evaluate the estimated value of V _abs depending on ; and/or the evaluation unit is configured to evaluate the phase V _{ang of} the evaluation depending on ; where A _e indicates the acceleration or estimated acceleration, where i denotes an imaginary number; and denotes the angular frequency. 21. The device (100) according to item 19 or 20, in which the evaluation unit (110) is configured to evaluate the estimated acceleration by implementing a function minimization method or a function maximization method depending on the function for obtaining the estimated acceleration and depending on the estimate of the sound pressure on said transducer of said loudspeaker. 22. The device according to paragraph 21, in which the function minimization method is the Nelder-Mead simplex method. 23. The device (100) according to item 21 or 22, in which the evaluation unit (110) is configured to evaluate and/or receive information about the mass as an estimated mass, and about the stiffness as an estimated stiffness, and about the resistance as an estimated resistance, and the evaluation unit (110) is configured to evaluate the estimated acceleration depending on the estimated mass, and depending on the estimated stiffness, and depending on the estimated resistance. 24. The device (100) according to item 23, in which, in order to evaluate the estimated acceleration, the evaluation unit (110) is designed with the possibility of minimizing where M denotes mass; K stands for hardness; R stands for resistance; and denotes the Euclidean norm, and where P _s indicates the estimated sound pressure at said transducer of said loudspeaker; and A _e (M,K,R) denotes the function to obtain the estimated speedup. 25. The device (100) according to item 24, in which the function A _e (M,K,R) for obtaining the estimated acceleration is given by Where denotes the maximum absolute value of the sound pressure at the said transducer of the said loudspeaker; i denotes an imaginary number; and denotes the angular frequency. 26. The device (100) according to any one of paragraphs 23-25, in which, for estimating the estimated phase, the evaluation unit (110) is designed with the possibility of minimizing , where P _ff denotes the pre-measured or pre-calculated pressure; V _ff denotes pre-measured or pre-calculated speed; where M denotes mass; K stands for hardness; R stands for resistance; and denotes the Euclidean norm. 27. The device (100) according to one of the previous paragraphs, in which to evaluate the estimated radiation impedance one of the one or more transducers of one loudspeaker of one or more loudspeakers the evaluation unit (110) is configured to evaluate the estimated radiation impedance by evaluating the information of the estimated sound pressure P _s , by evaluating two estimates of the speed , as information about the estimated velocity and by estimating the estimated radiation impedance depending on , where "mean" denotes a function that defines the average of two parameters, Where And - weighting factors that depend on the proximity of the microphone from one or more microphones to the said loudspeaker. 28. The device (100) according to one of the previous paragraphs, in which the evaluation unit (110) is configured to evaluate the estimated speed information depending on the current through the coil of the loudspeaker transducer of said transducer of said loudspeaker. 29. The device (100) according to item 28, in which the evaluation unit (110) is configured to evaluate the estimated speed information additionally depending on the electrical resistance , inductance coils, power coefficient , mechanical mass , full rigidity , mechanical resistance . 30. The device (100) according to clause 29, in which the evaluation unit (110) is configured to determine the estimated speed information based on a system of equations specified according to: , Where denotes the excitation signal; t stands for time; denotes the said speed of the converter of the said converter of the said loudspeaker; x denotes the axial displacement of the loudspeaker membrane of said loudspeaker; denotes the current through the coil of the loudspeaker transducer of the said loudspeaker transducer, where the designation " » denotes the first derivative with respect to time. 31. The device (100) according to clause 30, in which the evaluation unit (110) is designed with the ability to solve a system of equations using the fourth-order Runge-Kutta method. 32. The device (100) according to any one of paragraphs 1-7, in which the estimated speed information is stored in the device (100). 33. The device (100) according to clause 32, in which the estimated speed information is stored in a lookup table which is stored in the device (100), wherein the evaluation block (110) is configured to output information on the estimated speed from the lookup table. 34. The device (100) according to clause 33, in which the evaluation unit 110 is configured to output the estimated speed information from the lookup table using the excitation voltage level as an input to the lookup table. 35. The device (100) according to one of the preceding paragraphs, in which one or more loudspeakers are the first loudspeaker, wherein one or more transducers of the first loudspeaker are the first transducer of the first loudspeaker, the evaluation unit (110) is configured to evaluate the radiation resistance of the first transducer of the first loudspeaker as the estimated radiation resistance; or is configured to evaluate the radiation impedance of the first transducer of the first loudspeaker as the estimated radiation impedance. 36. The device (100) according to clause 35, wherein one or more input audio channels are a first input channel, and one or more output audio channels are a first output channel for the first transducer, the processing unit (120) is configured to determine a first filter for the first converter depending on the estimated radiation resistance or depending on the estimated radiation impedance and the processing unit (120) is configured to apply the first filter to the first converter on the first input channel to obtain the first output channel for the first converter. 37. The device (100) according to clause 36, in which the processing unit (120) is configured to determine an additional filter for each additional transducer of one or more additional transducers of each additional loudspeaker of one or more additional loudspeakers depending on the first filter for the first transducer and the processing unit (120) is configured to apply an additional filter of each additional converter of one or more additional converters of each additional loudspeaker of one or more additional loudspeakers on an additional input signal of one or more additional input signals to obtain an additional output signal of one or more additional output signals for said additional converter. 38. The device (100) according to clause 37, wherein the processing unit (120) is configured to determine a global frequency correction filter by determining an additional filter for at least one of the one or more additional transducers from at least one of the one or more additional loudspeakers, and the processing unit (120) is configured to use the initial raw filter curve of the first transducer for the one or more additional transducers to obtain a smoothed filter curve for at least one of the one or more additional transducers. 39. The device (100) according to clause 38, in which the processing unit (120) is configured to determine an additional filter for at least one of the one or more additional transducers from at least one of the one or more additional loudspeakers using a frequency limiter to limit the frequency correction to a frequency range for at least one of the one or more additional transducers. 40. The device (100) according to one of the previous paragraphs, in which the evaluation unit (110) is configured to evaluate two or more radiation resistances or two or more radiation impedances for two or more transducers of one or more loudspeakers, the processing unit (120) is configured to determine two or more raw filter curves for two or more transducers depending on two or more radiation resistances or two or more radiation impedances, the processing unit (120) is configured to determine a weighted-average filtration curve by determining a weighted average of two or more raw filtration curves or is configured to determine a smoothed weighted-average filtration curve by determining a smoothed weighted average of two or more raw filtration curves and the processing unit (120) is configured to apply a weighted-average filter curve, or a smoothed weighted-average filter curve, or a filter curve derived from the weighted-average filter curve or from the smoothed weighted-average filter curve, to an input audio signal from one or more input audio signals to obtain an output audio signal from one or more output audio signals for another converter other than the two or more converters. 41. The device (100) according to one of the preceding paragraphs, in which the processing unit (120) is configured to determine a filter for at least one of the one or more transducers of at least one of the one or more loudspeakers depending on a user-specified target frequency correction curve. 42. The device (100) according to one of the preceding paragraphs, in which the evaluation unit (110) is configured to predict the linear parameters of said transducer of said loudspeaker by solving a minimization problem for estimating the estimated radiation resistance or the estimated radiation impedance of said transducer of said loudspeaker. 43. The device (100) according to clause 42, in which the evaluation unit (110) is configured to predict the linear parameters of said transducer of said loudspeaker by solving a minimization problem using a cost function Where denotes the measured current; denotes the simulated current; denotes the Euclidean norm; and denotes a vector of unknown parameters with electrical resistance , inductance coils, power coefficient , with full rigidity , mechanical mass and mechanical resistance . 44. The device (100) according to one of the preceding paragraphs, in which the evaluation unit (110) is configured to use said estimated sound pressure information to evaluate said estimated speed information. 45. The device (100) according to clause 44, in which the evaluation unit (110) is designed with the possibility of using , Where - time derivative of estimated velocity information; - gradient operator; - information on estimated sound pressure in the time domain; - density of the medium. 46. The device (100) according to one of the preceding paragraphs, in which the processing unit (120) is configured to determine the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance and the processing unit (120) is configured to process one or more input audio channels depending on the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance. 47. The device (100) according to clause 46, in which the processing unit (120) is configured to change the spectral shape of at least one of the one or more input audio channels depending on the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance. 48. The device (100) according to clause 47, in which the processing unit (120) is configured to determine a spectral change coefficient for each spectral band of a plurality of spectral bands depending on the difference between the estimated radiation resistance of said transducer of said loudspeaker and a given radiation resistance for said spectral band, and wherein for each input audio channel of one or more input audio channels, in order to obtain one of the one or more output audio channels, the processing unit (120) is configured to apply the spectral change coefficient of each spectral band of the plurality of spectral bands on said spectral band of said input audio channel. 49. The device (110) according to any one of paragraphs 46-48, in which the processing unit (120) is configured to determine the difference between the estimated radiation resistance of said transducer of said loudspeaker and the specified radiation resistance according to , Where denotes the difference mentioned; denotes the estimated radiation resistance; denotes the specified radiation resistance; denotes the angular frequency. 50. The device (100) according to any one of paragraphs 46-48, in which the processing unit (120) is configured to apply a smoothing operation on said difference, which is a raw filter prototype, to obtain a smoothed filter prototype, and the processing unit (120) is configured to apply a smoothed prototype filter on at least one of the one or more input audio channels to obtain at least one of the one or more output audio channels. 51. The device (100) according to one of the preceding paragraphs, in which the processing unit (120) is configured to apply a global frequency equalizer on at least one of the one or more input audio channels to obtain at least one intermediate signal, the processing unit (120) is configured to determine the relative sound power in the spectral region from the estimated radiation resistance or from the estimated radiation impedance, the processing unit (120) is configured to determine one or more peaks in the relative sound power in the spectral region and the processing unit (120) is configured to apply an additional frequency corrector to at least one intermediate signal depending on one or more peaks in the relative sound power in the spectral region to obtain at least one of the one or more output audio channels. 52. The device (100) according to one of paragraphs 1-3, in which one or more microphones are remote from said loudspeaker, wherein the evaluation unit (110) is configured to evaluate the estimated sound pressure information depending on the captured sound pressure information recorded by one or more microphones. 53. The device according to paragraph 52, in which one or more microphones are remote from said loudspeaker. 54. The device (100) according to clause 52 or 53, in which one or more microphones are two or more microphones, the evaluation unit (110) is configured to receive captured sound pressure information from two or more microphones, the evaluation unit (110) is configured to use the captured sound pressure information from only one of the two or more microphones to determine the estimated sound pressure information and the evaluation unit (110) is configured to not use the captured sound pressure information from other microphones of the two or more microphones to determine the estimated sound pressure information. 55. The device (100) according to item 52 or 53, in which one or more microphones are two or more microphones, the evaluation unit (110) is configured to receive captured sound pressure information from two or more microphones, The evaluation unit (110) is configured to determine the average captured sound pressure information from two or more microphones and to determine the estimated sound pressure information using the average captured sound pressure information. 56. The device (100) according to clause 52 or 53, in which one or more microphones are two or more microphones, the evaluation unit (110) is configured to receive captured sound pressure information from two or more microphones, The evaluation unit (110) is configured to determine a weighted average of the captured sound pressure information from two or more microphones and to determine the estimated sound pressure information using the weighted average of the captured sound pressure information. 57. The device (100) according to clause 52 or 53, in which one or more microphones are two or more microphones, one or more loudspeakers comprise two or more loudspeakers and/or at least one of the one or more loudspeakers comprises two or more transducers, the evaluation unit (110) is configured to receive captured sound pressure information from two or more microphones, The evaluation unit (110) is configured to determine, for each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, a weighted average of the captured sound pressure information from two or more microphones and to determine the estimated sound pressure information using the weighted average of the captured sound pressure information, wherein the evaluation unit (110) is configured to determine said weighted average depending on a plurality of weighting factors, wherein each weighting factor from the plurality of weighting factors depends on the position of said transducer and depends on the position of each of the two or more microphones. 58. The device (100) according to clause 52 or 53, in which one or more microphones are two or more microphones, one or more loudspeakers comprise two or more loudspeakers and/or at least one of the one or more loudspeakers comprises two or more transducers, For each transducer of one or more transducers of one or more loudspeakers, the evaluation unit (110) is configured to select one of two or more microphones as the selected microphone, wherein for said transducer, the evaluation unit (110) is configured to use the captured sound pressure information from the selected microphone to determine the estimated sound pressure information, and wherein for said transducer, the evaluation unit (110) is configured to not use the captured sound pressure information from other microphones of the two or more microphones to determine the estimated sound pressure information. 59. The device (100) according to clause 58, in which, for each transducer of one or more transducers of one or more loudspeakers, the evaluation unit (110) is configured to select one of two or more microphones as the selected microphone depending on the position of said transducer and depending on the position of each of the two or more microphones. 60. The device (100) according to any one of paragraphs 52-59, in which the evaluation unit (110) is configured to determine the estimated sound pressure information using a complex transfer function. 61. The device (100) according to clause 60, in which the evaluation unit (110) is configured to determine the estimated sound pressure information according to , Where denotes estimated sound pressure information; denotes the captured sound pressure information; denotes the complex transfer function given by , Where denotes the angular frequency; denotes the applied sound pressure at the said loudspeaker; denotes the estimated sound pressure at said one of the one or more microphones that is present when the sound pressure exists on the said loudspeaker. 62. The device (100) according to any one of paragraphs 52-61, in which at least one of the one or more microphones (300) is not located in the main direction of radiation from any of the one or more loudspeakers (200). 63. The device (100) according to one of paragraphs 1-3, in which one or more microphones are remote from said loudspeaker, wherein at least one of the one or more microphones (300) does not have a direct line of sight to any of the one or more loudspeakers (200). 64. The device (100) according to one of paragraphs 1-3, in which one or more microphones are remote from said loudspeaker, wherein for each microphone of one or more microphones, the specified distance between said microphone and the loudspeaker is at least 10 cm. 65. The device (100) according to one of the preceding paragraphs, wherein the one or more input audio channels represent two or more input audio channels and the one or more output audio channels represent two or more output audio channels, the processing unit (120) is configured to obtain at least two of the two or more output audio channels by determining, depending on the estimated radiation resistance or depending on the estimated radiation impedance of at least one of the one or more transducers of each of the one or more loudspeakers, individual change information for each input audio channel of at least two of the two or more input audio channels and by applying individual change information for each input audio channel of at least two of the two or more input audio channels to said input audio channel. 66. The device (100) according to one of the preceding paragraphs, in which the evaluation unit (110) is configured to update the estimated radiation resistance or the estimated radiation impedance from one or more transducers of one or more loudspeakers upon initialization and/or on request and/or during a run. 67. The device (100) according to one of the preceding paragraphs, in which the estimated radiation resistance is the first estimated radiation resistance before the first time or the estimated radiation impedance is the first estimated radiation impedance before the first time, wherein the evaluation unit (110) is configured to evaluate the second radiation resistance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a second estimated radiation resistance after a second time; or is configured to evaluate the second radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a second estimated radiation impedance after a second time, wherein said second estimated radiation impedance of said transducer contains estimated information about the second radiation resistance of said transducer, wherein for estimating the second estimated radiation resistance or the second estimated radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers, the estimating unit (110) is configured to estimate the second estimated radiation resistance or the second estimated radiation impedance depending on the second estimated sound pressure information indicating the estimate of the second sound pressure on said transducer of said loudspeaker, and depending on the second estimated speed information indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker, wherein the evaluation unit (110) is configured to determine and output whether the device (100) is in the first state or in the second state depending on the difference in radiation resistances indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance, or depending on the difference in radiation impedances indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance, wherein the second state indicates that the device (100) is not functioning properly or that the device (100) has changed location, and the first state indicates that the device (100) is operating properly and that the device (100) has not changed location. 68. The device (100) according to clause 67, in which the evaluation unit (110) is configured to evaluate the second information of the estimated sound pressure depending on the captured second information of the sound pressure recorded by one or more microphones, and/or wherein the evaluation unit (110) is configured to evaluate the information of the second estimated speed depending on the second current through the coil of the loudspeaker transducer of said transducer of said loudspeaker. 69. The device (100) according to clause 67 or 68, in which the evaluation unit (110) is configured to determine a difference in radiation resistances by determining a difference value indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance; or is configured to determine a difference in radiation impedances by determining a difference value indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance, wherein the evaluation unit (110) is configured to determine that the device (100) is in the second state if the difference value is greater than the threshold value; and the evaluation unit (110) is configured to determine that the device (100) is in the first state if the difference value is less than or equal to the threshold value. 70. A device for automatically adapting a loudspeaker to the listening environment, the device comprising: evaluation block (110), wherein the evaluation unit (110) is configured to evaluate the first radiation resistance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a first estimated radiation resistance before the first point in time; or is configured to evaluate the first radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a first estimated radiation impedance before the first point in time, wherein said first estimated radiation impedance of said transducer contains estimated information about the first radiation resistance of said transducer, wherein for estimating the first estimated radiation resistance or the first estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimating unit (110) is configured to estimate the first estimated radiation resistance or the first estimated radiation impedance depending on the first estimated sound pressure information indicating the estimate of the sound pressure on said transducer of said loudspeaker before the first moment in time, and depending on the first estimated speed information indicating the estimate of the first speed of the transducer of said transducer of said loudspeaker before the first moment in time, wherein the evaluation unit (110) is configured to evaluate the second radiation resistance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a second estimated radiation resistance after a second time; or is configured to evaluate the second radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a second estimated radiation impedance after a second time, wherein said second estimated radiation impedance of said transducer contains estimated information about the second radiation resistance of said transducer, wherein the second time occurs after the first time, wherein for estimating the second estimated radiation resistance or the second estimated radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers, the estimating unit (110) is configured to estimate the second estimated radiation resistance or the second estimated radiation impedance depending on the second estimated sound pressure information indicating the estimate of the sound pressure on said transducer of said loudspeaker after the second time, and depending on the second estimated speed information indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker after the second time, wherein the evaluation unit (110) is configured to determine and output whether the device is in the first state or in the second state depending on the difference in radiation resistances indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance, or depending on the difference in radiation impedances indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance, where the second state indicates that the device is not working properly or that the device has changed location, and The first state indicates that the device is functioning properly and that the device has not changed location. 71. The device according to item 70, wherein the evaluation unit (110) is configured to evaluate the first estimated sound pressure information depending on the captured first sound pressure information recorded by one or more microphones before the first time point and the evaluation unit (110) is configured to evaluate the second estimated sound pressure information depending on the captured second sound pressure information recorded by one or more microphones after the second time point; and/or the evaluation unit (110) is configured to evaluate the information of the first estimated speed depending on the first current through the coil of the loudspeaker transducer of said transducer of said loudspeaker before the first moment in time and the evaluation unit (110) is configured to evaluate the information of the second estimated speed depending on the second current through the coil of the loudspeaker transducer of said transducer of said loudspeaker after the second moment in time. 72. The device according to clause 70 or 71, in which the evaluation unit (110) is configured to determine a difference in radiation resistances by determining a difference value indicating the difference between the second estimated radiation resistance and the first estimated radiation resistance; or is configured to determine a difference in radiation impedances by determining a difference value indicating the difference between the second estimated radiation impedance and the first estimated radiation impedance, wherein the evaluation unit (110) is configured to determine that the device is in the second state if the difference value is greater than the threshold value; and the evaluation unit (110) is configured to determine that the device is in the first state if the difference value is less than or equal to the threshold value. 73. A system for automatically adapting a loudspeaker to the listening environment, the system comprising: a device (100) according to any one of paragraphs 1-69; and loudspeaker (200), wherein the loudspeaker (200) is configured to output at least one of one or more output audio channels. 74. System according to clause 73, which further comprises one or more microphones (300). 75. A method for processing an input audio signal comprising one or more input audio channels to obtain an output audio signal comprising one or more output audio channels, wherein the method comprises the steps of: estimating the radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation resistance; or estimating the radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as an estimated radiation impedance, wherein said estimated radiation impedance of said transducer contains estimated information about the radiation resistance of said transducer, and one or more output audio channels are obtained by processing each input audio channel of the one or more input audio channels depending on the estimated radiation resistance or depending on the estimated radiation impedance of each of the one or more transducers of each of the one or more loudspeakers, wherein for estimating the estimated radiation resistance or the estimated radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers, the estimating of the estimated radiation resistance or the estimated radiation impedance is performed using at least one of the estimated sound pressure information and the estimated speed information, wherein the estimated sound pressure information indicates an estimate of the sound pressure at said transducer of said loudspeaker instead of measuring the sound pressure directly at said transducer, and wherein the estimated speed information indicates an estimate of the speed of the transducer for said transducer of said loudspeaker instead of measuring the speed of the transducer directly at said transducer. 76. A method for automatically adapting a loudspeaker to a listening environment, the method comprising the steps of: estimating the first radiation resistance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a first estimated radiation resistance before a first point in time; or estimating the first radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers as a first estimated radiation impedance before a first point in time, wherein said first estimated radiation impedance of said transducer contains estimated information about the first radiation resistance of said transducer; wherein for estimating the first estimated radiation resistance or the first estimated radiation impedance of each transducer of one or more transducers of each loudspeaker of one or more loudspeakers, the estimation of the first estimated radiation resistance or the first estimated radiation impedance is carried out depending on the information of the first estimated sound pressure indicating the estimate of the sound pressure on said transducer of said loudspeaker before the first moment in time, and depending on the information of the first estimated speed indicating the estimate of the first speed of the transducer of said transducer of said loudspeaker before the first moment in time; estimating a second radiation resistance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a second estimated radiation resistance after a second time; or estimating a second radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers as a second estimated radiation impedance after a second time, wherein said second estimated radiation impedance of said transducer contains estimated information about the second radiation resistance of said transducer, wherein the second time occurs after the first time; wherein for estimating the second estimated radiation resistance or the second estimated radiation impedance of each transducer of the one or more transducers of each loudspeaker of the one or more loudspeakers, the second estimated radiation resistance or the second estimated radiation impedance is estimated depending on the second estimated sound pressure information indicating the estimate of the sound pressure on said transducer of said loudspeaker after a second time, and depending on the second estimated speed information indicating the estimate of the second speed of the transducer of said transducer of said loudspeaker after a second time; and determining and deducing whether the device is in a first state or a second state, depending on a difference in radiation resistances indicating a difference between a second estimated radiation resistance and a first estimated radiation resistance, or depending on a difference in radiation impedances indicating a difference between a second estimated radiation impedance and a first estimated radiation impedance, wherein the second state indicates that the device is not working properly or that the device has changed location, and the first state indicates that the device is working properly and that the device has not changed location. 77. A data carrier containing a computer program for implementing the method according to claim 75 when executed on a computer or signal processor. 78. A data carrier containing a computer program for implementing the method according to claim 76 when executed on a computer or signal processor.