WO2020059977A1 - Continuously steerable second-order differential microphone array and method for configuring same - Google Patents

Abstract

An embodiment of the present invention provides a steerable second-order differential microphone array, the array comprising: an input unit for receiving a plurality of input sound signals through a microphone array including a plurality of microphones fixedly arranged on one plane; and a processor for calculating second-order back-to-back cardioid responses by using the plurality of input sound signals, calculating a monopole response, first-order orthogonal dipole responses, and second-order orthogonal dipole responses by using the second-order back-to-back cardioid responses, and calculating a second-order DMA response steered at a given angle by using the monopole response, the first-order orthogonal dipole responses, and the second-order orthogonal dipole responses.

Description

Continuously steerable secondary differential microphone array and how to configure it

The present invention relates to a secondary differential microphone array (DMA) that can be continuously steered and a method for constructing the same. Specifically, the present invention relates to a secondary differential microphone array capable of continuously steering a directional direction while having higher directivity than a primary differential microphone array, and a method for constructing the same.

Efforts have been made to continuously acquire a sound source in a desired direction and reduce noise in an environment where noise sources and background noise are affected by using a microphone array.

A typical additive microphone array needs to consider various conditions such as the physical size of the microphone device and the length of the array suitable for a real environment. Due to these constraints, there are limitations in selecting an algorithm for beamformer design.

A differential microphone array (DMA) is a structure that forms a beam using a spatial derivative of an acoustic pressure field, and can be implemented at a narrow microphone distance, making it an important option in voice communication applications. . The value of usability can be increased by adjusting the main lobe of the DMA in the desired direction. Due to the nature of the DMA where the main lobe is formed in the end-fire direction, in order to adjust the main lobe in a desired direction, a microphone array should be arranged in the corresponding direction. Therefore, an algorithm that can continuously steer the directional direction is required even for a fixed microphone array arrangement.

In the related art, a first DMA algorithm that can be continuously steered was introduced, and additional studies were conducted accordingly. In general, in a rectangular array structure, a primary combination of a monopole and two orthogonal dipoles can continuously steer the primary DMA. However, the secondary DMA could not be continuously steered due to technical difficulties.

The above-mentioned background art is technical information acquired by the inventor for the derivation of the present invention or acquired in the derivation process of the present invention, and is not necessarily a known technology disclosed to the general public prior to the filing of the present invention.

The present invention is to provide an apparatus and a method for configuring a secondary differential microphone array to be continuously steerable, and calculating a secondary differential microphone array response steered in a given direction, so as to effectively increase the collection directivity using the microphone array do.

In addition, the present invention is to provide a noise canceling apparatus and method for calculating a secondary differential microphone array response steered in a given direction without generating a phase difference between each of the calculated responses.

According to an embodiment of the present invention, a microphone array is configured according to a predetermined arrangement of 7 or 9 microphones, including one central microphone. Then, the secondary back-to-back cardioid responses are calculated using the input sound signals received from the respective microphones, and the unipolar response, the primary orthogonal dipole responses, and the secondary orthogonal dipole responses are calculated using the secondary back-to-back cardioid responses. Then, the secondary differential microphone array response steered by a given angle is calculated using unipolar response, primary orthogonal dipole responses, and secondary orthogonal dipole responses.

According to various embodiments of the present invention, since the second DMA algorithm is used compared to the conventionally steerable primary DMA, the direction of sound collection can be further increased, and a simple microphone array composed of only 7 or 9 microphones is optional. Steering is also possible in the direction of, so it can be downsized.

In addition, according to various embodiments of the present invention, since the calculated unipolar response calculated from the secondary back-to-back cardioid responses, the primary orthogonal dipole responses and the secondary orthogonal dipole responses are calculated, the calculated secondary DMA response is calculated. There is no phase difference between the responses, and thus there is an advantage of not having to perform an operation to correct a separate phase difference.

1 is a block diagram showing a configuration of a secondary differential microphone array 100 that can be continuously steered according to an embodiment of the present invention.

2 is a flowchart illustrating a method of configuring a secondary differential microphone array that can be continuously steered according to an embodiment of the present invention.

3 is a view showing a portion of a microphone array according to an embodiment of the present invention.

4 is a view showing a first microphone array according to an embodiment of the present invention.

5 is a view showing a second microphone array according to an embodiment of the present invention.

6 is a view showing a third microphone array according to an embodiment of the present invention.

7 is a view showing beam patterns of primary back-to-back cardioid responses according to an embodiment of the present invention.

8 is a view showing a beam pattern of unipolar response according to an embodiment of the present invention.

9 is a view showing a beam pattern of primary orthogonal dipole responses according to an embodiment of the present invention.

10 is a view showing a beam pattern of a primary orthogonal dipole response steered according to an embodiment of the present invention.

11 is a view showing a part of a beam pattern among secondary back-to-back cardioid responses according to an embodiment of the present invention.

12 is a view showing a part of the beam pattern among the quadratic orthogonal dipole responses according to an embodiment of the present invention.

13 is a view showing a beam pattern of a secondary orthogonal dipole response steered according to an embodiment of the present invention.

14 to 17 are diagrams illustrating a beam pattern of a secondary DMA response steered according to an embodiment of the present invention.

18 is a view showing a result of measuring a white noise gain using a continuously steerable secondary DMA according to an embodiment of the present invention.

19 is a diagram showing a directional index using a continuously steerable secondary DMA according to an embodiment of the present invention.

Hereinafter, exemplary embodiments disclosed herein will be described in detail with reference to the accompanying drawings, but the same or similar elements are assigned the same reference numbers regardless of the reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "modules" and "parts" for the components used in the following description are given or mixed only considering the ease of writing the specification, and do not have meanings or roles distinguished from each other in themselves. In addition, in describing the embodiments disclosed in the present specification, when it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed herein, detailed descriptions thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the specification is not limited by the accompanying drawings, and all modifications included in the spirit and technical scope of the present invention , It should be understood to include equivalents or substitutes.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

1 is a block diagram showing a configuration of a secondary differential microphone array 100 that can be continuously steered according to an embodiment of the present invention.

Referring to FIG. 1, the terminal 100 may include a processor 110, an input unit 120, a memory 130, a communication unit 140, and a power supply unit 150.

The processor 110 controls the overall operation of the secondary differential microphone array 100, which is typically continuously steerable. The processor 110 may provide or process appropriate information or functions to a user by processing signals, data, information, etc. input or output through the following components or by driving an application program stored in the memory 130.

In addition, the processor 110 may control at least some of the components illustrated in FIG. 1 to drive an application program stored in the memory 130. Furthermore, the processor 110 may operate by combining at least two or more of the components included in the secondary differential microphone array 100 that can be continuously steered to drive the application program.

Here, the processor may refer to a data processing device embedded in hardware having physically structured circuits, for example, to perform functions represented by codes or instructions included in a program. As an example of such a data processing device embedded in hardware, a microprocessor, a central processing unit (CPU), a processor core, a multiprocessor, and an application-specific integrated ASIC circuit), a field programmable gate array (FPGA), and the like, but the scope of the present invention is not limited thereto.

The input unit 120 receives the ambient sound and includes a microphone array 121 composed of a plurality of fixed microphones.

The microphone array 121 may include 7 or 9 microphones on the same plane.

At this time, the microphone array 121 may be composed of MEMS (Micro Electro-Mechanical Systems) microphones. Since the MEMS microphone is small, it is possible to miniaturize the microphone array 121.

At this time, the microphones included in the microphone array 121 are arranged with narrow intervals, so that the lengths of the horizontal and vertical sides of the microphone array 121 may be smaller than the wavelength of the sound source in the audible frequency band.

The memory 130 stores data supporting various functions of the secondary differential microphone array 100 that can be continuously steered.

The memory 130 is for a plurality of applications (application programs or applications) driven in the continuously steerable secondary differential microphone array 100, for the operation of the continuously steerable secondary differential microphone array 100. Data, instructions can be stored.

The memory 130 may separately store and store sound signals received from microphones included in the microphone array 121. The stored sound signals can be stored temporarily or permanently.

The communication unit 140 may transmit and receive data to and from a device using a sound signal such as a microphone array, a speaker, or a sound signal processing device through wired or wireless communication.

Under the control of the processor 110, the power supply 150 supplies power to each component included in the secondary differential microphone array 100 that is continuously steerable by receiving external power and internal power. The power supply 150 includes a battery, and the battery may be a built-in battery or a replaceable battery.

2 is a flowchart illustrating a method of configuring a secondary differential microphone array that can be continuously steered according to an embodiment of the present invention.

Referring to FIG. 2, the processor 110 of the secondary differential microphone array 100 that can be continuously steered receives input sound signals through the microphone array 121 composed of a plurality of microphones (S201).

The microphone array 121 can be classified according to the number of the plurality of microphones constituting and the arrangement thereof, and the present invention proposes a total of three microphone arrays.

The first microphone array is composed of nine microphones, and a detailed description thereof will be described with reference to FIG. 4.

The second microphone array is composed of nine microphones, and a detailed description thereof will be described with reference to FIG. 5.

The third microphone array is composed of seven microphones, and a detailed description thereof will be described with reference to FIG. 6.

The continuously steerable primary DMA uses a microphone array composed of four microphones as shown in FIG. 3, but in the present invention, a microphone array composed of seven or nine microphones to continuously steer the secondary DMA To use.

To describe the continuously steerable secondary DMA 100 according to an embodiment of the present invention, a primary DMA that can be steered continuously with reference to FIG. 3 will be described.

3 is a view showing a portion of a microphone array according to an embodiment of the present invention.

Referring to FIG. 3, in order to configure a continuously steerable secondary DMA, a primary steerable DMA must first be constructed, which is a microphone array composed of four microphones 121_1, 121_2, 121_3 and 121_4 ( 121).

Each of the microphones 121_1, 121_2, 121_3 and 121_4 is disposed in the same plane (eg, xy plane). The first microphone pair 121_1 and 121_2 is arranged on the x-axis, and the second microphone pair 121_3 and 121_4 is arranged on the y-axis. That is, the first microphone pair and the second microphone pair are disposed perpendicular to each other in the same plane.

Each of the microphones 121_1, 121_2, 121_3, and 121_4 is arranged to be separated by an equal distance d / 2 from the origin. That is, the microphones included in each microphone pair are arranged to be separated from each other by a distance d.

At this time, in order to configure the DMA, the distance d between the microphones must satisfy the condition of Equation 1 below. λ is the wavelength of the sound source.

However, here, the distance d between the microphones is not a distance between all microphones, but a reference of a distance between microphones that are grouped into one group or set.

For example, when viewing the first microphone pair 121_1 and 121_2 as one set, d may mean a distance between the first microphone 121_1 and the second microphone 121_2.

4 to 6, when the central microphone 121_0 is included, and the first microphone pair 121_1 and 121_2 and the central microphone 121_0 are viewed as one set, d is the first microphone 121_1 and the central microphone. It may mean a distance between (121_0) and a distance between the central microphone (121_0) and the second microphone (121_2).

That is, the microphone array 121 is configured such that the distance between microphones included in the same microphone pair is much smaller than half the wavelength of the sound source to be input. For example, it may be configured to be smaller than half the wavelength of sound in the audible frequency band.

When the condition of [Equation 1] is satisfied, the normalized 1 ^st- order DMA response R ₁ in which the directional direction is steered by θ _s from the reference axis (eg, the x-axis) is 1 [ Equation 2] can be approximated.

δ _m is the normalized monopole response, and D ₁ is the normalized 1 ^st- order response with the directional direction steered to θ _s . a _1,1 and a _1,2 are coefficients that determine directivity, and the sum of a _1,1 and a _1,2 is 1. θ is the angle from the reference axis (eg, x-axis) in the microphone array plane (xy plane).

That is, the normalized primary DMA response in which the directional direction is steered can be expressed as a weighted sum of the normalized unipolar response and the normalized primary dipole response in which the directional direction is steered.

At this time, the unipolar response δ _m (θ) sums sound signals input from all the microphones 121_1, 121_2, 121_3, and 121_4, or the primary back-to-back cardioid. It can be composed of the sum of responses.

D ₁ (θ, θ _s ) of [Equation 2] may be expressed as [Equation 3] below.

δ _{1, x} (θ) is the primary x-axis orthogonal dipole response (or first primary orthogonal dipole response) obtained from the first microphone pair 121_1 and 121_2, and δ _{1, y} (θ) is the second Primary y-axis orthogonal dipole response (or second primary orthogonal dipole response) obtained from microphone pairs 121_3 and 121_4.

When the microphones 121_1, 121_2, 121_3, and 121_4 are arranged as shown in FIG. 3, the first primary orthogonal dipole response and the second primary orthogonal dipole response are as follows: [Equation 4] and [Equation 5] Can be expressed as τ ₀ is d / c, c is the speed of sound, and ω is the angular frequency.

When the microphones 121_1, 121_2, 121_3, and 121_4 including the origin microphone 121_0 are disposed as shown in FIGS. 4 to 6, the first primary orthogonal dipole response and the second primary orthogonal dipole response are as follows. Equation 6] and [Equation 7]. τ ₀ is d / c, c is the speed of sound, and ω is the angular frequency.

To calculate the first DMA response that can be continuously steered, the first dipole response D ₁ (θ, θ _s ) that can be steered at any angle is required. A secondary dipole response D ₂ (θ, θ _s ) that can be steered at any angle is required.

When the condition of [Equation 1] is satisfied, a normalized 2nd DMA response in which the directional direction according to an embodiment of the present invention is steered by θ _s from a reference axis (eg, x-axis) is normalized 2 ^nd -order DMA response) R ₂ may be approximated as in [Equation 8] below.

a _2,1 , a _2,2 and a _2,3 are coefficients for determining directivity, and the sum of a _2,1 , a _2,2 and a _2,3 is 1.

The second dipole response is expressed as [Equation 9] to [Equation 11] using [Equation 3].

δ _{2, x} (θ) is the secondary x-axis orthogonal dipole response (or first secondary quadrature dipole response) obtained from the origin microphone 121_0 and the first microphone pair 121_1 and 121_2, and δ _{2, y} (θ) is the secondary y-axis orthogonal dipole response (or second secondary orthogonal dipole response) obtained from the origin microphone 121_0 and the second microphone pair 121_3 and 121_4.

In [Equation 9], the last term is expressed as a product of the first primary orthogonal dipole response and the second primary orthogonal dipole response. However, when a DMA response is obtained using the input of each microphone and the responses are combined, multiplication of the response is impossible to implement in a real system. Therefore, the present invention is approached in a different way.

The last term of [Equation 9] may be represented by [Equation 15] to [Equation 17] using [Equation 12] to [Equation 14] below.

From [Equation 16], it can be seen that δ _{2, + q} (θ) is a second-order orthogonal dipole response in a 45-degree direction from a reference axis (x-axis), which can be referred to as a third secondary orthogonal dipole response.

Similarly, from [Equation 17], it can be seen that δ _{2, -q} (θ) is a quadratic orthogonal dipole response in the -45 degree direction from the reference axis (x-axis), which is referred to as a fourth quadratic orthogonal dipole response. You can.

The present invention revealed that the product of two primary orthogonal dipole responses can be expressed as the difference between the third orthogonal dipole response and the fourth secondary orthogonal dipole response using the triangular law.

Furthermore, the present invention can be configured to continuously steer secondary DMA by using the microphone array 121 in which additional microphones 121_5 to 121_8 are arranged in accordance with the meanings of [Equation 16] and [Equation 17]. It showed that there is. This will be described in detail with reference to FIG. 4 below.

4 is a view showing a first microphone array according to an embodiment of the present invention.

The first microphone array illustrated in FIG. 4 is a microphone array corresponding to Equations 16 and 17 above. In the microphone array, microphones are arranged to match the meaning of the equation derived through mathematical induction.

Referring to FIG. 4, the first microphone array includes nine microphones 121_0 to 121_8 in the same microphone array plane (eg, xy plane).

The central microphone 121_0 is arranged at the origin of the microphone array.

The first pair of microphones 121_1 and 121_2 are arranged on the x-axis, the second pair of microphones 121_3 and 121_4 are arranged on the y-axis, and the third pair of microphones 121_5 and 121_6 is a straight line in the direction of 45 degrees from the x-axis (y = x), and the fourth microphone pairs 121_7 and 121_8 are disposed on a straight line (y = -x) in the -45 degree direction from the x-axis.

That is, the first microphone pair and the second microphone pair are arranged perpendicular to each other in the same plane, and the third microphone pair and the fourth microphone pair are arranged perpendicular to each other in the same plane.

In addition, the microphones included in each microphone pair are symmetrically arranged based on the central microphone 121_0. For example, the first microphone 121_1 and the second microphone 121_2 included in the first microphone pair are symmetrically arranged with respect to each other with respect to the central microphone 121_0.

만큼 떨어져 배치된다.The first to fourth microphones 121_1 to 121_4 are arranged at the same distance d from the central microphone 121_0, and the fifth to eighth microphones 121_5 to 121_8 are the same distance from the central microphone 121_0.

As far as it is placed.

Accordingly, the secondary DMA response steered according to an embodiment of the present invention can be expressed by arranging [Equation 8] and [Equation 18] below.

That is, according to an embodiment of the present invention, the secondary DMA response steered at an arbitrary angle may be calculated using the unipolar response, the primary dipole responses, and the secondary dipole responses obtained using the first microphone array. .

Hereinafter, a second microphone array composed of nine microphones 121_0 to 121_8 through an approximation process will be described with reference to FIG. 5.

5 is a view showing a second microphone array according to an embodiment of the present invention.

The second microphone array shown in FIG. 5 is a microphone array including nine microphones constructed according to an approximate equation when the assumption of [Equation 1] holds.

[Equation 6], [Equation 7], [Equation 10], [Equation 11], [Equation 16] and [Equation 17] according to the following [Equation 19], [Equation 19] 20] to [Equation 25].

Through the approximation process, since the term for the distance d between the angular frequency ω and the microphone in [Equation 20] to [Equation 25] is removed, as shown in FIG. 5, the microphones 121_1 to 121_8 except the central microphone 121_0 ) May be disposed on concentric circles so as to be separated by the same distance d from the central microphone 121_0.

Specifically, the second microphone array includes nine microphones 121_0 to 121_8 in the same microphone array plane (eg, xy plane).

The central microphone 121_0 is arranged at the origin of the microphone array.

The first pair of microphones 121_1 and 121_2 are arranged on the x-axis, the second pair of microphones 121_3 and 121_4 are arranged on the y-axis, and the third pair of microphones 121_5 and 121_6 is a straight line in the direction of 45 degrees from the x-axis (y = x), and the fourth microphone pairs 121_7 and 121_8 are disposed on a straight line (y = -x) in the -45 degree direction from the x-axis.

That is, the first microphone pair and the second microphone pair are arranged perpendicular to each other in the same plane, and the third microphone pair and the fourth microphone pair are arranged perpendicular to each other in the same plane.

In addition, the microphones included in each microphone pair are symmetrically arranged based on the central microphone 121_0. For example, the first microphone 121_1 and the second microphone 121_2 included in the first microphone pair are symmetrically arranged with respect to each other with respect to the central microphone 121_0.

The first to eighth microphones 121_1 to 121_8 are disposed at the same distance d from the central microphone 121_0.

That is, according to an embodiment of the present invention, the secondary DMA response steered at an arbitrary angle may be calculated using the unipolar response, the primary dipole responses, and the secondary dipole responses obtained using the second microphone array. .

Hereinafter, a third microphone array composed of seven microphones 121_0 to 121_6 through an approximation process will be described with reference to FIG. 6.

6 is a view showing a third microphone array according to an embodiment of the present invention.

The third microphone array shown in FIG. 6 is a microphone array including seven microphones constructed according to an equation approximating [Equation 15].

[Equation 15] may be approximated to [Equation 26] using the approximated [Equation 20] to [Equation 25].

Since the term for the fourth quadratic dipole response δ _{2, -q} in [Equation 26] is removed through the approximation process, the third microphone array is from the x-axis in the second microphone array of FIG. 5 as shown in FIG. It may be configured by excluding the seventh microphone 121_7 in the 45 degree direction and the eighth microphone 121_8 in the 135 degree direction.

In this case, [Equation 18] may be summarized as [Equation 27] using [Equation 26].

Specifically, the third microphone array includes seven microphones 121_0 to 121_6 in the same microphone array plane (eg, xy plane).

The central microphone 121_0 is arranged at the origin of the microphone array.

The first pair of microphones 121_1 and 121_2 are arranged on the x-axis, the second pair of microphones 121_3 and 121_4 are arranged on the y-axis, and the third pair of microphones 121_5 and 121_6 is a straight line in the direction of 45 degrees from the x-axis (y = x).

That is, the first microphone pair and the second microphone pair are disposed perpendicular to each other in the same plane.

In addition, the microphones included in each microphone pair are symmetrically arranged based on the central microphone 121_0. For example, the first microphone 121_1 and the second microphone 121_2 included in the first microphone pair are symmetrically arranged with respect to each other with respect to the central microphone 121_0.

The first to sixth microphones 121_1 to 121_6 are disposed at the same distance d from the central microphone 121_0.

That is, according to an embodiment of the present invention, the secondary DMA response steered at an arbitrary angle may be calculated using the unipolar response, the primary dipole responses, and the secondary dipole responses obtained using the third microphone array. .

In the above, it has been described that a second DMA that can be continuously steered can be configured using the first to third microphone arrays.

Returning to the description of FIG. 2 again, the processor 110 of the continuously steerable secondary differential microphone array 100 responds to a 2nd-order back-to-back cardioid using input sound signals. Calculate them (S203).

In the present invention, in order to solve the phase mismatch problem that may occur in the process of combining the response (output) of different orders, the unipolar response and the dipole response are configured using the secondary back-to-back cardioid responses. To this end, the second back-to-back cardioid responses are calculated.

Secondary back-to-back cardioid responses can be calculated as [Equation 28] to [Equation 31] below.

In [Equation 28] to [Equation 31], ± means the direction (front or back) of the cardioid.

는 기준 축(x축) 방향으로의 2차 백투백 카디오이드 응답으로, 제1 2차 백투백 카디오이드 응답이라 칭한다.

Is a secondary back-to-back cardioid response in the direction of the reference axis (x-axis), and is referred to as a first secondary back-to-back cardioid response.

는 기준 축(x축)으로부터 180도 방향으로의 2차 백투백 카디오이드 응답으로, 제2 2차 백투백 카디오이드 응답이라 칭한다.

Is a second back-to-back cardioid response from the reference axis (x-axis) 180 degrees, and is referred to as a second second back-to-back cardioid response.

는 기준 축(x축)으로부터 90도 방향으로의 2차 백투백 카디오이드 응답으로, 제3 2차 백투백 카디오이드 응답이라 칭한다.

Is a second back-to-back cardioid response in a 90 degree direction from a reference axis (x-axis), and is called a third second back-to-back cardioid response.

는 기준 축(x축)으로부터 270도 방향으로의 2차 백투백 카디오이드 응답으로, 제4 2차 백투백 카디오이드 응답이라 칭한다.

Is a secondary back-to-back cardioid response from the reference axis (x-axis) in the direction of 270 degrees, and is referred to as a fourth secondary back-to-back cardioid response.

는 기준 축(x축)으로부터 45도 방향으로의 2차 백투백 카디오이드 응답으로, 제5 2차 백투백 카디오이드 응답이라 칭한다.

Is the second back-to-back cardioid response in the direction of 45 degrees from the reference axis (x-axis), and is referred to as the fifth second back-to-back cardioid response.

는 기준 축(x축)으로부터 225도 방향으로의 2차 백투백 카디오이드 응답으로, 제6 2차 백투백 카디오이드 응답이라 칭한다.

Is a secondary back-to-back cardioid response from the reference axis (x-axis) in the direction of 225 degrees, and is referred to as a sixth secondary back-to-back cardioid response.

는 기준 축(x축)으로부터 135도 방향으로의 2차 백투백 카디오이드 응답으로, 제7 2차 백투백 카디오이드 응답이라 칭한다.

Is a secondary back-to-back cardioid response from the reference axis (x-axis) in the direction of 135 degrees, and is referred to as a seventh secondary back-to-back cardioid response.

는 기준 축(x축)으로부터 315도 방향으로의 2차 백투백 카디오이드 응답으로, 제8 2차 백투백 카디오이드 응답이라 칭한다.

Is a secondary back-to-back cardioid response in the direction of 315 degrees from the reference axis (x-axis), and is referred to as an eighth secondary back-to-back cardioid response.

Accordingly, according to Equations 28 to 31, the processor 110 calculates secondary back-to-back cardioid responses from the combination of each microphone pair and the central microphone 121_0.

The processor 110 calculates the first differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the first input signal obtained from the first microphone 121_1, and the second microphone ( 121_2) to calculate the first secondary back-to-back cardioid response by subtracting the second input signal.

The processor 110 calculates the second differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the second input signal obtained from the second microphone 121_2, and the first microphone ( 121_1) subtract the first input signal obtained to calculate a second secondary back-to-back cardioid response.

The processor 110 calculates the third differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the third input signal obtained from the third microphone 121_3, and the fourth microphone ( 121_4) subtract the fourth input signal to calculate the third secondary back-to-back cardioid response.

The processor 110 calculates the fourth differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the fourth input signal obtained from the fourth microphone 121_4, and the third microphone ( 121_3) to calculate the fourth secondary back-to-back cardioid response by subtracting the third input signal.

The processor 110 calculates a fifth differential signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the fifth input signal obtained from the fifth microphone 121_5, and from the fifth differential signal to the sixth microphone ( 121_6) subtract the sixth input signal to calculate the fifth secondary back-to-back cardioid response.

The processor 110 calculates the sixth differential signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the sixth input signal obtained from the sixth microphone 121_6, and the fifth microphone from the sixth differential signal ( The fifth input signal obtained in 121_5) is subtracted to calculate the sixth secondary back-to-back cardioid response.

The processor 110 calculates the seventh differential signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the seventh input signal obtained from the seventh microphone 121_7, and the eighth microphone from the seventh differential signal ( 121_8) to calculate the 7th 2nd back-to-back cardioid response by subtracting the 8th input signal.

The processor 110 calculates the eighth difference signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the eighth input signal obtained from the eighth microphone 121_8, and the seventh microphone ( Subtract the seventh input signal obtained in 121_7) to calculate the eighth secondary back-to-back cardioid response.

When the processor 110 acquires input sound signals from the first microphone array or the second microphone array, the processor 110 has a total of eight secondary back-to-back cardioid responses (first to eighth second back-to-back cardioid responses) Calculate

When the processor 110 acquires input sound signals from the third microphone array, the processor 110 calculates a total of six secondary back-to-back cardioid responses (first to sixth second back-to-back cardioid responses).

The processor 110 of the continuously steerable secondary differential microphone array 100 calculates a monopole response using secondary back-to-back cardioid responses (S205).

The processor 110 may calculate a unipolar response using the calculated second back-to-back cardioid responses.

At this time, the processor 110 may calculate a unipolar response by summing all of the calculated second back-to-back cardioid responses.

At this time, the processor 110, as shown in Equation (32), combines the first secondary back-to-back cardioid response, the second secondary back-to-back cardioid response, the third secondary back-to-back cardioid response, and the fourth secondary back-to-back cardioid response as a single-pole response. Can be calculated.

The processor 110 of the continuously steerable secondary differential microphone array 100 calculates primary 1st-order orthogonal dipole responses using secondary back-to-back cardioid responses (S207).

The processor 110 may calculate primary orthogonal dipole responses using the calculated secondary back-to-back cardioid responses.

At this time, the processor 110 may calculate the primary orthogonal dipole responses by subtracting the calculated secondary back-to-back cardioid responses.

At this time, the processor 110 may calculate primary orthogonal dipole responses by subtracting each other from the calculated second back-to-back cardioid responses, which correspond to directions of the second back-to-back cardioid. The meaning that the directions correspond means that the directions are 180 degrees apart from each other.

At this time, the processor 110 may calculate first orthogonal dipole responses by subtracting the first to fourth secondary back-to-back cardioid responses in the x-axis and y-axis directions from among the calculated secondary back-to-back cardioid responses.

At this time, the processor 110 may calculate the primary orthogonal dipole responses as shown in [Equation 33].

At this time, the processor 110 calculates the first primary orthogonal dipole response by subtracting the second secondary back-to-back cardioid response from the first secondary back-to-back cardioid response, and the fourth secondary back-to-back cardioid response from the third secondary back-to-back cardioid response Subtracting, we can calculate the second primary orthogonal dipole response.

The processor 110 of the continuously steerable secondary differential microphone array 100 calculates 2nd-order orthogonal dipole responses using secondary back-to-back cardioid responses (S209).

The processor 110 may calculate secondary quadrature dipole responses using the calculated second-to-back cardioid responses.

At this time, the processor 110 may calculate the secondary orthogonal dipole responses by summing the calculated secondary back-to-back cardioid responses.

In this case, the processor 110 may calculate primary orthogonal dipole responses by summing the second back-to-back cardioid responses corresponding to each other among the calculated second-to-back cardioid responses. The meaning that the directions correspond means that the directions are 180 degrees apart from each other.

At this time, the processor 110 may calculate quadratic orthogonal dipole responses as shown in Equation 34 below.

At this time, the processor 110 calculates the first second orthogonal dipole response by adding the first second back-to-back cardioid response and the second second back-to-back cardioid response, and the third second back-to-back cardioid response and the fourth second back-to-back cardioid response. Adds to calculate the 2nd quadrature orthogonal dipole response, adds the 5th 2nd back-to-back cardioid response and the 6th 2nd back-to-back cardioid response, calculates the 3rd 2nd orthogonal dipole response, and the 7th 2nd back-to-back cardioid response 8 The fourth quadratic orthogonal dipole response can be calculated by summing the quadratic back-to-back cardioid responses.

In this case, when the microphone array 121 has the structure of the first microphone array or the second microphone array, the processor 110 may calculate first to fourth second orthogonal dipole responses.

At this time, when the microphone array 121 has the structure of the third microphone array, the processor 110 may calculate only the first to third second orthogonal dipole responses.

In this way, the processor 110 calculates the unipolar response, the first orthogonal dipole responses, and the second orthogonal dipole responses by combining the second back-to-back cardioid responses, thereby obtaining the second DMA response steered according to Equation (8). It is possible to solve the problem of phase mismatch of unipolar responses, primary orthogonal dipole responses, and secondary orthogonal dipole responses used for calculation.

Therefore, the continuously steerable secondary DMA according to an embodiment of the present invention does not have a problem of phase mismatch between calculated responses without a process for matching phases separately.

The processor 110 of the continuously steerable secondary differential microphone array 100 calculates a secondary DMA response steered by a given steering angle using unipolar response, primary orthogonal dipole responses, and secondary orthogonal dipole responses ( S211).

The processor 110 may calculate a secondary DMA response steered by a given steering angle θ _s from a unipolar response, primary orthogonal dipole responses, and secondary orthogonal dipole responses calculated according to Equation (8).

The steering angle θ _s has a range of 0 degrees to 360 degrees, and may be a value set by a user or automatically. That is, a given angle is not limited to a fixed value, but refers to an arbitrary angle from 0 to 360 degrees, so the feature of the present invention is that it can calculate a secondary DMA response steered by any desired angle. .

In this case, the steering angle θ _s may mean an angle in a direction corresponding to a position of a sound source that makes a sound to be collected through the microphone array 121. For example, when there is a sound source in the direction of 30 degrees based on the x-axis, the steering angle θ _s may be 30 degrees.

At this time, the steering angle θ _s may be that the processor 110 analyzes the input voice signals to calculate the position or direction of the sound source, and sets the calculated position or direction angle of the sound source. For example, the processor 110 may set the steering angle θ _s to 60 degrees when analyzing the input voice signals and determining that the current sound source direction is in the 60 degree direction based on the x-axis.

At this time, when the processor 110 recognizes the user's starting word from the input voice signals, the processor 110 calculates the position or direction from which the user issued the starting word, and the steering angle θ _s as the calculated angle of the user's position or direction Can be set. For example, the processor 110 may set the steering angle to 90 degrees when the user analyzes input voice signals including the starting word and determines that the location where the user issues the starting word is 90 degrees based on the x-axis.

At this time, when the structure of the microphone array 121 is the first microphone array or the second microphone array, the processor 110 may have a unipolar response, primary orthogonal dipole responses, and secondary quadrature calculated according to Equation 18 above. From the dipole responses it is possible to calculate a secondary DMA response steered by a given steering angle (or desired steering angle) θ _s .

Specifically, when the structure of the microphone array 121 is a first microphone array or a second microphone array, the processor 110 may include a calculated unipolar response; A primary orthogonal dipole response steered by θ _s calculated from the first and second primary orthogonal dipole responses; And a secondary orthogonal dipole response steered by θ _s calculated from the first to fourth secondary orthogonal dipole responses to calculate a secondary DMA response steered by θ _s .

At this time, when the structure of the microphone array 121 is a third microphone array, the processor 110 is given from the unipolar response, primary orthogonal dipole responses, and secondary orthogonal dipole responses calculated according to Equation 27 above. The secondary DMA response steered by the steering angle (or desired steering angle) θ _s can be calculated.

Specifically, when the structure of the microphone array 121 is a third microphone array, the processor 110 includes a calculated unipolar response; A primary orthogonal dipole response steered by θ _s calculated from the first and second primary orthogonal dipole responses; And a secondary orthogonal dipole response steered by θ _s calculated from the first to third secondary orthogonal dipole responses to calculate a secondary DMA response steered by θ _s .

In an optional embodiment, calculating the unipolar response (S205), calculating the primary orthogonal dipole responses (S207) and calculating the secondary orthogonal dipole responses (S209) are performed in parallel with each other or are performed The order can be reversed.

According to the present invention, there is an advantage of calculating a secondary DMA response steered by an arbitrary angle θ _s using a microphone array composed of only 7 microphones or 9 microphones, and has higher directivity than the existing primary DMA The performance is more excellent.

7 is a view showing beam patterns of primary back-to-back cardioid responses according to an embodiment of the present invention.

Specifically, FIG. 7 shows four primary back-to-back cardioid responses obtained using the first microphone pair 121_1 and 121_2 and the second microphone pair 121_3 and 121_4.

Hereinafter, the primary back-to-back cardioid response in the 0 degree (x-axis) direction is the first primary back-to-back cardioid response 701, and the primary back-to-back cardioid response in the 180 degree (-x-axis) direction is the second primary back-to-back cardioid response. (702), the first back-to-back cardioid response in the 90-degree (y-axis) direction to the third primary back-to-back cardioid response 703, and the first back-to-back cardioid response in the 270-degree (-y-axis) direction to the fourth primary back-to-back This is called cardioid response 704.

The processor 110 calculates the first primary back-to-back cardioid response 701 by subtracting the input signal of the second microphone 121_2 from the input signal of the first microphone 121_1, and from the input signal of the second microphone 121_2. The second primary back-to-back cardioid response 702 may be calculated by subtracting the input signal of the first microphone 121_1.

Similarly, the processor 110 calculates the third primary back-to-back cardioid response 703 by subtracting the input signal of the fourth microphone 121_4 from the input signal of the third microphone 121_3, and inputs the fourth microphone 121_4 The fourth primary back-to-back cardioid response 704 may be calculated by subtracting the input signal of the third microphone 121_3 from the signal.

8 is a view showing a beam pattern of unipolar response according to an embodiment of the present invention.

Referring to FIG. 8, the processor 110 may include a first primary back-to-back cardioid response 701, a second primary back-to-back cardioid response 702, and a third primary back-to-back cardioid response 703 and 4 The unipolar response 801 can be calculated by summing all the primary back-to-back cardioid responses 704.

9 is a view showing a beam pattern of primary orthogonal dipole responses according to an embodiment of the present invention.

Specifically, FIG. 9 uses the first primary orthogonal dipole response 901 in the 0 degree (x-axis) direction obtained using the first microphone pair 121_1 and 121_2 and the second microphone pair 121_3 and 121_4. The second primary orthogonal dipole response 902 in the 90-degree (y-axis) direction obtained is illustrated.

The processor 110 subtracts the second primary back-to-back cardioid response 702 from the first primary back-to-back cardioid response 701 to calculate a first primary orthogonal dipole response (0 degree direction or x-axis direction, 901), The second primary orthogonal dipole response (90-degree direction or y-axis direction, 902) may be calculated by subtracting the fourth primary back-to-back cardioid response 704 from the third primary back-to-back cardioid response 703.

10 is a view showing a beam pattern of a primary orthogonal dipole response steered according to an embodiment of the present invention.

Specifically, FIG. 10 illustrates a primary orthogonal dipole response in which the direction of directivity is steered 60 degrees relative to a reference axis (x-axis) using a unipolar response, a first primary orthogonal dipole response, and a second primary orthogonal dipole response. City.

The processor 110 may obtain a primary orthogonal dipole response in which the direction of directivity is steered at an arbitrary angle through operations on a unipolar response, a first primary orthogonal dipole response, and a second primary orthogonal dipole response.

11 is a view showing a part of a beam pattern among secondary back-to-back cardioid responses according to an embodiment of the present invention.

Specifically, FIG. 11 shows four secondary back-to-back cardioid responses obtained using the first microphone pair 121_1 and 121_2, the second microphone pair 121_3 and 121_4, and the central microphone 121_0.

Hereinafter, the second back-to-back cardioid response in the 0 degree (x-axis) direction is the first second back-to-back cardioid response 1101, and the second back-to-back cardioid response in the 180-degree (-x-axis) direction is the second second back-to-back cardioid response. (1102), a second back-to-back cardioid response in the 90-degree (y-axis) direction, a third second-to-back cardioid response (1103), and a second back-to-back cardioid response in the 270-degree (-y-axis) direction to a fourth second back-to-back It is referred to as the cardioid response 1104.

In addition, although not shown in FIG. 11, the second back-to-back cardioid response in the 45 degree direction, the fifth second back-to-back cardioid response in the 45 degree direction, and the second back-to-back cardioid response in the 225 degree direction, the sixth second back-to-back cardioid response, 135 degree direction The second back-to-back cardioid response is referred to as the seventh second back-to-back cardioid response and the second back-to-back cardioid response in the direction of 315 degrees is the eighth second back-to-back cardioid response.

As described above, the processor 110 calculates the first differential signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the first input signal obtained from the first microphone 121_1, and the first differential signal Subtract the second input signal obtained from the second microphone 121_2 to calculate the first secondary back-to-back cardioid response 1101.

The processor 110 calculates the second differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the second input signal obtained from the second microphone 121_2, and the first microphone ( 121_1), the second input back-to-back cardioid response 1102 is calculated by subtracting the first input signal.

The processor 110 calculates the third differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the third input signal obtained from the third microphone 121_3, and the fourth microphone ( 121_4) is subtracted to calculate the third secondary back-to-back cardioid response 1103.

The processor 110 calculates the fourth differential signal by subtracting the zero input signal obtained from the central microphone 121_0 from the fourth input signal obtained from the fourth microphone 121_4, and the third microphone ( 121_3) to calculate the fourth secondary back-to-back cardioid response 1104 by subtracting the third input signal.

The processor 110 calculates a fifth differential signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the fifth input signal obtained from the fifth microphone 121_5, and from the fifth differential signal to the sixth microphone ( 121_6) to calculate the fifth secondary back-to-back cardioid response 1105 by subtracting the sixth input signal.

The processor 110 calculates the sixth difference signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the sixth input signal obtained from the sixth microphone 121_6, and the fifth microphone from the sixth difference signal ( 121_5), the sixth second back-to-back cardioid response 1106 is calculated by subtracting the fifth input signal.

The processor 110 calculates a seventh difference signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the seventh input signal obtained from the seventh microphone 121_7, and the eighth microphone ( 121_8) to calculate the seventh secondary back-to-back cardioid response 1107 by subtracting the eighth input signal.

The processor 110 calculates the eighth difference signal by subtracting the zeroth input signal obtained from the central microphone 121_0 from the eighth input signal obtained from the eighth microphone 121_8, and the seventh microphone ( The 7th input signal obtained in 121_7) is subtracted to calculate the 8th 2nd back-to-back cardioid response 1108.

In addition, the processor 110 includes a first secondary back-to-back cardioid response 1101, a second secondary back-to-back cardioid response 1102, a third secondary back-to-back cardioid response 1103, and a fourth secondary back-to-back shown in FIG. The unipolar response can be calculated by summing all the cardioid responses 1104.

12 is a view showing a part of the beam pattern among the quadratic orthogonal dipole responses according to an embodiment of the present invention.

Specifically, FIG. 12 shows a first quadratic orthogonal dipole response 1201 in a 0 degree (x-axis) direction obtained using the first microphone pair 121_1 and 121_2 and the central microphone 121_0, and the second microphone pair ( 121_3 and 121_4) and a second secondary orthogonal dipole response 1202 in a 90 degree (y-axis) direction obtained using the central microphone 121_0.

The processor 110 calculates a first second orthogonal dipole response (0 degree direction or x-axis direction, 1201) by adding the first second back-to-back cardioid response 1101 and the second second back-to-back cardioid response 1102, The second secondary orthogonal dipole response (90-degree direction or y-axis direction, 1202) may be calculated by adding the third secondary back-to-back cardioid response 1103 and the fourth secondary back-to-back cardioid response 1104.

Also, although not shown in FIG. 12, the processor 110 calculates a third second orthogonal dipole response (45-degree direction) by adding the fifth second back-to-back cardioid response and the sixth second back-to-back cardioid response, and the seventh second The fourth second orthogonal dipole response (135 degree direction) may be calculated by adding the second back to back cardioid response and the eighth second back to back cardioid response.

13 is a view showing a beam pattern of a secondary orthogonal dipole response steered according to an embodiment of the present invention.

Specifically, FIG. 13 shows a quadratic orthogonal dipole response in which the direction of directivity is steered 60 degrees relative to the reference axis (x-axis).

The processor 110 is a quadratic orthogonal dipole that steers the direction of directivity at an arbitrary angle through calculations on a unipolar response, a first secondary orthogonal dipole response, a second secondary orthogonal dipole response, and a third secondary orthogonal dipole response. You can get a response.

In addition, the processor 110 determines the direction of directionality through operations on the unipolar response, the first secondary orthogonal dipole response, the second secondary orthogonal dipole response, the third secondary orthogonal dipole response, and the fourth secondary orthogonal dipole response. Secondary orthogonal dipole responses steered at any angle can be obtained.

Here, the unipolar response may be calculated as a sum of four primary back-to-back cardioid responses, but may be calculated as a sum of four secondary back-to-back cardioid responses.

The processor 110 calculates a unipolar response by summing the first secondary back-to-back cardioid response, the second secondary back-to-back cardioid response, the third secondary back-to-back cardioid response, and the fourth secondary back-to-back cardioid response, and calculates the unipolar response thus calculated. Can be used to compute the quadratic orthogonal dipole response steering at any angle.

14 to 17 are diagrams illustrating a beam pattern of a secondary DMA response steered according to an embodiment of the present invention.

When steering using the algorithm proposed in the present invention, it can be confirmed that the beam pattern of any secondary DMA is substantially constant regardless of the steering angle.

In [Equation 8], [Equation 18], or [Equation 27], by adjusting the weights (a _1,1 , a _1,2 , a _1,3 ) of each element, it can be adjusted to various types of beams 14 to 17, a _2,1 = -1 / 5, a _2,2 = 2/5, a _2,3 = 4/5, the second hyper-cardioid from the reference axis (x axis) θ The response when the main lobe was adjusted by _s = 0 °, 45 °, 135 ° and 225 ° is shown.

In particular, FIGS. 14 to 17 show the secondary DMA response in the case where the microphone array 121 has the 7-microphone structure shown in FIG. 5 above. That is, it can be confirmed that even in the 7-microphone structure having the most approximation among the embodiments of the present invention, the change in the shape of the beam pattern is very small as the steering angle is adjusted.

18 is a view showing a result of measuring a white noise gain using a continuously steerable secondary DMA according to an embodiment of the present invention.

FIG. 18 shows a white noise gain (WNG) for a 1KHz fixed frequency case of a secondary cardioid when d = 20 mm in the microphone array 121, the x-axis is a steering angle (θ _s ), and the y-axis is WNG.

Ideal represents the reference value of WNG, Direct is WNG when the microphone array 121 has the 9-microphone structure shown in FIG. 3 (first microphone array), and 9-mic Config is the microphone array 121. WNG, 7-mic Config in the case of having a 9-microphone structure shown in 4 (second microphone array), the case where the microphone array 121 has a 7-microphone structure shown in FIG. 5 (third microphone array) It is WNG when I have it.

The first microphone array is a microphone array that has not been subjected to an approximation process, shows a relatively low WNG when compared to the structure of other microphone arrays, and a relatively large change in WNG with respect to a change in steering angle (θ _s ). This is a result derived because the distance between the same microphones is not guaranteed.

On the other hand, the second microphone array is a microphone array having a 9-microphone structure that has undergone an approximation process, maintains a consistently high WNG, and exhibits small variation in WNG with respect to a change in steering angle θ _s .

The third microphone array is a microphone array having a 7-microphone structure that has been subjected to an approximation process, and generally has a high WNG, but when the steering angle θ _s is -π / 4 and + 3ð / 4, the WNG decreases rapidly. This is due to the omission of the dipole component in the -ð / 4 direction (-45 degree direction) through the approximation process.

Although the third microphone array has a loss of 2dB of WNG compared to the second microphone array at some steering angles, it is cheaper and more efficient than the microphone arrays of other structures in practical implementation because the number of microphones required for implementation is the smallest. However, if performance is a top priority, it is most effective to use a second microphone array.

In particular, the fluctuation range of the WNG in FIG. 18 is within about 2 dB, which means that despite the change in the steering angle, the deviation of the WNG is considerably small and has excellent performance.

19 is a diagram showing a directional index using a continuously steerable secondary DMA according to an embodiment of the present invention.

FIG. 19 shows a directivity index (DI) for a 1KHz fixed frequency case of a secondary cardioid when d = 20mm in the microphone array 121, the x-axis is a steering angle θ _s , and the y-axis is DI .

DI is generally calculated by [Equation 35] below, and B is a beam pattern. The following [Equation 36] is an equation for calculating DI from the continuously steerable secondary DMA response according to an embodiment of the present invention.

DI is a value obtained by dividing the power of the beam at a specific steering angle by the power of the entire beam pattern, and is an index indicating the performance of directivity.

Referring to FIG. 19, the continuously steerable secondary DMA composed of a first microphone array, a second microphone array, or a third microphone array according to an embodiment of the present invention all has a variation of DI within 0.1 dB.

Therefore, according to an embodiment of the present invention, even if a continuous steering secondary DMA for all directions is configured with only 7 microphones or 9 microphones, the directivity maintains a constant level and has excellent performance.

As described above, the continuously steerable secondary DMA composed of the first microphone array, the second microphone array, or the third microphone array according to an embodiment of the present invention continuously maintains the secondary DMA response while maintaining the shape of the beam pattern. Steering at an angle is possible. In addition, the directionality or white noise gain fluctuation according to the steering is kept small, and high performance can be expected.

Accordingly, since the secondary DMA is used in comparison with the conventional continuously steerable primary DMA, there is an advantage in that steering can be continuously performed while maintaining more stable performance while being more directional.

The above-described present invention can be embodied as computer readable codes on a medium on which a program is recorded. The computer-readable medium includes any kind of recording device in which data readable by a computer system is stored. Examples of computer-readable media include a hard disk drive (HDD), solid state disk (SSD), silicon disk drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage device. There is this. In addition, the computer may include a processor 180 of the terminal.

The display device described above is not limited to the configuration and method of the above-described embodiments, and the above embodiments may be configured by selectively combining all or part of each embodiment so that various modifications can be made. It might be.

Claims (13)

In a steerable secondary differential microphone array (DMA), An input unit for receiving a plurality of input sound signals through a microphone array composed of a plurality of fixed microphones arranged in one plane; And Calculate second-order back-to-back cardioid responses using the input sound signals, calculate unipolar response, first-order orthogonal dipole responses and second-order orthogonal dipole responses using the second-to-back cardioid responses, and perform the unipolar response, first order Processor for computing a quadratic DMA response steered at a given angle using orthogonal dipole responses and quadratic orthogonal dipole responses A second differential microphone array that can be steered. The method according to claim 1, The processor Calculate a primary orthogonal dipole response steered at the given angle using the primary orthogonal dipole responses, Calculate a quadratic quadrature response steered at the given angle using the quadratic quadrature dipole responses, A steerable secondary differential microphone calculating a secondary DMA response steered at the given angle using the unipolar response, the primary orthogonal dipole response steered at the given angle and the secondary orthogonal dipole response steered at the given angle Array. The method according to claim 1, The microphone array A central microphone and first to fourth microphones, The first to fourth microphones When arranged at a distance d from the central microphone, when the central microphone is set as the origin of the plane and one direction from the origin is set as a reference axis on the plane, 0, 90, and 180 degrees from the reference axis, respectively. A steerable secondary differential microphone array, arranged in degrees and 270 degrees. The method according to claim 3, The processor Using the zeroth input signal received from the central microphone, the first input signal received from the first microphone and the second input signal received from the second microphone, corresponding to 0 degrees and 180 directions from the reference axis, respectively. Calculate a first second back-to-back cardioid response and a second second back-to-back cardioid response; A third 2 corresponding to directions of 90 degrees and 270 degrees from the reference axis, respectively, using the zeroth input signal, the third input signal received from the third microphone, and the fourth input signal received from the fourth microphone, respectively. A steerable secondary differential microphone array that calculates a primary back-to-back cardioid response and a fourth secondary back-to-back cardioid response. The method according to claim 4, The processor Calculating a first primary orthogonal dipole response and a first secondary orthogonal dipole response using the first secondary back-to-back cardioid response and the second secondary back-to-back cardioid response; A steerable secondary differential microphone array for calculating a second primary orthogonal dipole response and a second secondary orthogonal dipole response using the third secondary back-to-back cardioid response and the fourth secondary back-to-back cardioid response. The method according to claim 3, The microphone array One of the first microphone array, the second microphone array, and the third microphone array, The first microphone array and the second microphone array Further comprising a fifth to eighth microphone, The third microphone array A second steerable differential microphone array further comprising fifth and sixth microphones. The method according to claim 6 The first microphone array The fifth to eighth microphones are the distance from the central microphone

Separated by 45 degrees, 135 degrees, 225 degrees and 315 degrees from the reference axis, respectively; The second microphone array The fifth to eighth microphones are arranged at a distance d from the central microphone, 45 degrees, 135 degrees, 225 degrees and 315 degrees respectively from the reference axis; The third microphone array The fifth and sixth microphones are spaced apart by a distance d from the central microphone, and are arranged in the direction of 45 degrees and 225 degrees, respectively, from the reference axis. The method according to claim 7, The processor A fifth second corresponding to 45 degrees and 225 directions from the reference axis, respectively, using the zeroth input signal, the fifth input signal received from the fifth microphone, and the sixth input signal received from the sixth microphone, respectively. Calculate the back-to-back cardioid response and the sixth second back-to-back cardioid response; When the microphone array is the first microphone array or the second microphone array, using the zeroth input signal, the seventh input signal received from the seventh microphone and the eighth input signal received from the eighth microphone , A seventh secondary back-to-back cardioid response and an eighth secondary back-to-back cardioid response corresponding to 135 degrees and 315 directions, respectively, from the reference axis. The method according to claim 8, The processor Calculating a third second orthogonal dipole response using the fifth second back-to-back cardioid response and the sixth second back-to-back cardioid response; Steering, when the microphone array is the first microphone array or the second microphone array, calculating a fourth second quadrature orthogonal dipole response using the seventh second back-to-back cardioid response and the eighth second back-to-back cardioid response Possible secondary differential microphone array. The method according to claim 4, The processor A steerable secondary differential microphone that calculates the unipolar response by summing the first second back-to-back cardioid response, the second second back-to-back cardioid response, and the fourth second back-to-back cardioid response and the fourth second back-to-back cardioid response . The method according to claim 3, The microphones MEMS (Micro Electro-Mechanical Systems) microphone, The distance d is A steerable secondary differential microphone that is less than half the wavelength corresponding to sound in the audible frequency range. Receiving a plurality of input sound signals through a microphone array composed of a plurality of fixed microphones arranged in one plane; Calculating secondary back-to-back cardioid responses using the plurality of input sound signals; Calculating unipolar responses, primary orthogonal dipole responses and secondary orthogonal dipole responses using the secondary back-to-back cardioid responses; And Calculating a secondary DMA response steered at a given angle using the unipolar response, the primary orthogonal dipole responses, and the secondary orthogonal dipole responses. A method of constructing a steerable secondary differential microphone array comprising a. A recording medium in which a program for performing a method for constructing a steerable secondary differential microphone array is recorded, The method for constructing the steerable secondary differential microphone array Receiving a plurality of input sound signals through a microphone array composed of a plurality of fixed microphones arranged in one plane; Calculating secondary back-to-back cardioid responses using the plurality of input sound signals; Calculating unipolar responses, primary orthogonal dipole responses and secondary orthogonal dipole responses using the secondary back-to-back cardioid responses; And Calculating a secondary DMA response steered at a given angle using the unipolar response, the primary orthogonal dipole responses, and the secondary orthogonal dipole responses. Included, recording medium.

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