JP2000060847A - Biological sound detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heart sound detector capable of obtaining heart sound signals with less environmental sound. SOLUTION: In a cancellation sound signal output device 27, in a signal processing condition decision means 74, a signal processing condition A for successively outputting cancellation sound signals SC for indicating cancellation sound based on pseudo environmental sound successively detected by an environmental sound microphone 20 is decided in the state of generating the pseudo environmental sound stored beforehand from an external speaker 30. In the state of not generating the pseudo environmental sound from the external speaker 30, by an environmental sound processing means 76, the environmental sound detected by the environmental sound microphone 20 is processed based on the signal processing condition A decided in the signal processing condition decision means 74, the cancellation sound signals SC are successively decided, cancellation sound is outputted from a cancellation sound speaker 42 based on the cancellation sound signals SC and thus, the environmental sound propagated through viable tissues is canceled by the cancellation sound. Thus, since the detection of the environmental sound passed through the viable tissues and emitted from the skin 14 again by a heart sound microphone 12 is suppressed, the heart sound signals SH with less environmental sound are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a body sound generated in a body and outputs a body sound signal representing the body sound in order to diagnose a disease such as a heart or a respiratory system of the body. The present invention relates to a sound detection device, and more particularly to a body sound detection device capable of removing an environmental sound signal representing an environmental sound generated outside a living body from the body sound signal.

[0002]

2. Description of the Related Art For example, in order to diagnose a living body disease such as a heart disease or a respiratory system, a heart sound, a respiratory sound, a pleural sound, an arterial sound which are mounted on the skin of a predetermined part of the living body and are generated in the living body. 2. Description of the Related Art Diagnosis is performed using a body sound detection device that detects a body sound such as intestinal sound and outputs a body sound signal representing the body sound. For example, a heart sound detecting device mounted on the skin of the chest detects a heart sound to measure a heart sound chart, and a heart disease is diagnosed from the heart sound chart. When a patient has a heart disease, the phonocardiogram obtained by measuring the patient includes a normal heart sound and a murmur generated due to the heart disease. Can be done.

The above-mentioned body sound detecting device detects the vibration of the skin due to the transmission of the sound wave of the body sound, that is, the body sound wave, and the vibration of the skin is detected from the skin side opening of the body sound detecting device. An air conduction type that is transmitted to the air inside the body sound detection device and detects body sound based on the vibration of the air, or the vibration of the skin is transmitted to one member of the body sound detection device that is in contact with the skin of the living body. , There is a direct conduction type that detects a body sound based on the vibration of one of the members.

Among the above-mentioned body sound detecting devices, the air conduction type body sound detecting device has an advantage that it is less aging and more robust than the direct conduction type body sound detecting device.

[0005]

However, in the body sound signal output from the body sound detecting device, in addition to the body sound necessary for diagnosis, environmental sounds generated by persons other than the person to be measured, such as human speech, Since footsteps and door opening / closing sounds are included, it may be difficult to make an accurate diagnosis. In particular, the air conduction type biological sound detection device detects the biological sound based on the vibration of the air, so that it is easily affected by the environmental sound, and in particular, a part of the environmental sound is the biological tissue of the measurement subject. Since it was difficult to separate it from the body sound because it propagated through and had a wide frequency band, the environment sound emitted again from the epidermis via the body tissue was included in the body sound signal. There was a problem of being lost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a living body sound detecting device which can obtain a living body sound signal with less environmental sound.

[0007]

[Means for Solving the Problem] As a result of various investigations against the background described above, the present inventor has detected the environmental sound detected by the body sound microphone before detecting the body sound microphone. From the environmental sound detected earlier, a sound with the opposite phase and the same amplitude as the environmental sound detected by the body sound microphone is determined, and the determined sound is changed to the environmental sound detected by the body sound microphone. It was found that the environmental sound detected by the body sound microphone can be canceled before being detected by the body sound microphone by outputting the sound toward the body sound microphone. The present invention was made based on such findings.

That is, the gist of the first invention is that a body sound microphone is mounted on the skin of a living body, detects a body sound generated in the body, and outputs a body sound signal representing the body sound. A body sound detecting device comprising: (a) provided at a position above the body sound microphone and separated from the skin of the living body by a predetermined distance, to set the environmental sound around the body sound detecting device. Environmental sound microphone that detects sequentially (b)
Based on the environmental sound that is sequentially detected by the environmental sound microphone,
A cancel sound signal output device that sequentially outputs a cancel sound signal that is the same environmental sound that is sequentially detected by the environmental sound microphone and that represents a cancel sound for canceling the environmental sound that propagates to the biological sound microphone, (c) a cancel sound speaker that is provided at a position where the distance to the body sound microphone is shorter than the environmental sound microphone, and that outputs a cancel sound based on the cancel sound signal output from the cancel sound signal output device, To include.

[0009]

[Effect of the first invention] With this configuration, since the environmental sound microphone is provided above the living body sound microphone and at a position separated from the skin of the living body by a predetermined distance, the environmental sound microphone emits the environmental sound. Based on the environmental sound sequentially detected by the environmental sound microphone, the cancel sound signal output device sequentially propagates to the biological sound microphone as the environmental sound that is the same as the environmental sound sequentially detected by the environmental sound microphone. A cancel sound signal representing a cancel sound for canceling the environmental sound is sequentially output, and based on the cancel sound signal, the cancel sound speaker provided at a position where the distance from the body sound microphone is shorter than the environmental sound microphone cancels. Since the sound is output, the environmental sound detected by the biological sound microphone is canceled by the cancel sound. Therefore, a biological sound signal with less environmental sound can be obtained.

[0010]

A second aspect of the present invention for attaining the above object is to provide a housing having a housing which is opened in one direction and whose opening side is brought into close contact with a living body, and a diaphragm. Then, provided with a living body sound microphone having a microphone element for converting the vibration of the diaphragm into an electric signal provided in the housing, and is mounted on the skin of the living body to detect the living body sound generated in the living body. A body sound detecting device for outputting a body sound signal representing the body sound from the body sound microphone, wherein (a) the body sound microphone is provided on the outer peripheral side of the body sound microphone with respect to the microphone element. A sound insulation device, and (b) an environmental sound microphone that is provided above the living body sound microphone and at a position separated from the skin of the living body by a predetermined distance to sequentially detect the environmental sound around the living body sound detecting device. And (c) a pseudo-environmental sound generator that generates a pre-stored pseudo-environmental sound, and (d-1) the pseudo-environmental sound generated by the pseudo-environmental sound generator. A signal processing condition determination for determining a signal processing condition for sequentially outputting a cancel sound signal representing a cancel sound for canceling the environmental sound propagating to the body sound microphone based on the pseudo environmental sound sequentially detected by the microphone. Means, and (d-2) in a state where a pseudo-environmental sound is not generated from the pseudo-environmental sound generation device, detected by the environmental sound microphone based on the signal processing condition determined by the signal processing condition determining means. A canceling sound signal output device including an environmental sound processing unit that determines the canceling sound signal by processing the environmental sound, and (e) the living body sound microphone rather than the environmental sound microphone. Provided the distance is short positions of the click, and a cancel sound speaker for outputting canceling sounds based on the output canceling sound signal from the cancellation sound signal output device is to comprise.

[0011]

According to the second aspect of the invention, the environmental sound propagating directly from the air to the housing is blocked by the sound insulating device and is not detected by the microphone element. Then, since the environmental sound microphone is provided above the biological sound microphone and at a position separated from the skin of the living body by a predetermined distance, the environmental sound microphone sequentially detects the environmental sound, and in the cancel sound signal output device, In the signal processing condition determining means, the environmental sound microphones are sequentially arranged so that the simulated environmental sound detected by the biological sound microphone is minimized while the pre-stored pseudo environmental sound is generated from the pseudo environmental sound generator. Based on the detected pseudo-environmental sound, the signal processing condition for sequentially outputting the cancel sound signal representing the cancel sound for canceling the environmental sound propagating to the biological sound microphone is determined, and the pseudo-environment sound generator generates the pseudo environment. In the state where no sound is generated, the environment sound processing means determines the environment based on the signal processing conditions determined by the signal processing condition determining means. The environmental sound detected by the microphone is processed and the cancellation sound signal is sequentially determined, and based on the cancellation sound signal, the cancellation sound is canceled from the cancellation sound speaker provided at a position closer to the living body sound microphone than the environmental sound microphone. Since the sound is output, the environmental sound propagating through the living tissue is canceled by the cancel sound. Therefore,
The vibrating plate of the microphone element is suppressed from being vibrated by the environmental sound emitted again from the skin via the biological tissue, so that the biological sound signal with less environmental sound is obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a heart sound detection device 10 to which the present invention is applied and which detects a heart sound as a body sound.

In FIG. 1, a heart sound microphone 12 functioning as a body sound microphone is placed on a predetermined heart sound detection site on the skin 14 of a living body in a supine state, detects a heart sound, and outputs a heart sound signal SH representing the heart sound. Output. The sound insulation wall 16 has a circular shape with an opening having a diameter of several times the horizontal length of the heart sound microphone 12 and a depth (height) from several times the vertical length of the heart sound microphone 12. The bowl shape is about ten times larger, and the opening side is brought into contact with the skin 14 with the heart sound microphone 12 positioned at the center of the opening surface. The sound insulation wall 16 functions as a fixing device for fixing the environmental sound microphone 20 and the cancellation sound speaker 42, which will be described later, and is made of a material having a relatively high sound insulation effect, that is, a material having a relatively heavy specific gravity (such as iron) or the like. A sound absorbing material (for example, a porous material such as glass wool) is sandwiched between materials having a relatively high specific gravity, and the ambient sound around the heart sound microphone 12 propagates in the air to directly transmit the sound. It also has the function of preventing the detection by 12.

An environmental sound microphone 20 is fixedly installed on the outer surface of the closed bottom portion 18 of the sound insulation wall 16 (hence above the heart sound microphone 12), and detects the environmental sound around the heart sound microphone 12 to represent the environmental sound. The environmental sound signal SN _t is output. The environmental sound signal SN _t output from the environmental sound microphone 20 is output by the sample / hold circuit 22 to a predetermined sampling cycle T.
It is sampled by _S and digitized by the A / D converter 24. The sample-and-hold circuit 22 uses the predetermined period T
_In addition to sampling the environmental sound signal SN _t at _S , when sequentially outputting the input environmental sound signal SN _t to the A / D converter 24, the A / D for the environmental sound signal SN _t output last time is output.
It also has a function of holding the environmental sound signal SN _t to be output next, until the conversion operation in the D converter 24 is completed. Then, the signal digitized by the A / D converter 24 is supplied to the high-speed arithmetic processing unit 26.

The high-speed arithmetic processing unit 26 is, for example, a DSP (digital signal processor) equipped with a product-sum arithmetic circuit.
Is the same environmental sound as the environmental sound sequentially detected by the environmental sound microphone 20 based on the signals sequentially input from the sample and hold circuit 22 via the A / D converter 24, and It functions as a cancel sound signal output device 27 that sequentially outputs a cancel sound signal SC that represents a cancel sound for canceling the propagating environmental sound, and is provided at a position separated from the heart sound microphone 12 and the environmental sound microphone 20 to provide a pseudo environmental sound. A pseudo-environmental sound signal SN _f representing a pseudo-environmental sound is output to the external speaker 30 functioning as a generator, and is further output from the heart sound microphone 12 and represented by the heart sound signal SH digitized by the A / D converter 28. The waveform is displayed on the display 32. When the signal from the A / D converter 24 is processed by the high-speed arithmetic processing unit 26 between the environmental sound microphone 20 and the sample and hold circuit 22, the spectrum represented by the signal, that is, the area A low-pass filter 34 is provided to avoid singing, and the frequency of the environmental sound signal SN _t supplied to the sample and hold circuit 22 is the sampling frequency f _s (=
It is limited to a frequency band equal to or less than ½ of (1 / T).

The cancel sound signal SC output from the high-speed arithmetic processing unit 26 is converted into an analog signal in the D / A converter 36, provided between the environmental sound microphone 20 and the sample and hold circuit 22, and is a low-pass filter. 34
The cancel sound signal SC converted into an analog signal is limited to a frequency band equal to or less than _½ of the sampling frequency f _s by the low-pass filter 38 having the same configuration as above, and the signal amplifier 40 amplifies the signal. The cancel sound is output from the cancel sound speaker 42 fixed to the inner surface of the bottom portion 18 of the sound insulation wall 16.

The bottom portion 18 of the sound insulation wall 16 prevents the cancellation sound output from the cancellation sound speaker 42 from being detected by the environmental sound microphone 20.
6 is thicker than the portion other than the bottom portion 18. In addition, the same sound as the sound detected by the environmental sound microphone 20,
That is, before the sound represented by the wavefront 43 propagates to the heart sound microphone 12, the cancel sound signal SC is determined based on the environmental sound detected by the environmental sound microphone 20, and the cancel sound speaker 42 outputs the cancel sound. The cancel sound interferes with the sound represented by the wavefront 43, and the sound must be canceled. Therefore, the cancel sound speaker 42 needs to be provided at least at a position where the distance to the heart sound microphone 12 is shorter than that of the environmental sound microphone 20, and the high-speed arithmetic processing device 26 that functions as the cancel sound signal output device 27 is extremely short. Cancel sound signal SC from the environmental sound detected by environmental sound microphone 20 at time
Need to decide.

FIG. 2 is a sectional view for explaining the structure of the heart sound microphone 12. The heart sound microphone 12 is a housing including a relatively short cylindrical lower housing 44 and a bottomed cylindrical upper housing 46 which is fitted into the lower housing 44 to form a short cylindrical space between the lower housing 44 and the lower housing 44. 47, a microphone element 50 fitted into a fitting hole 48 provided on the upper housing 46 side at the axial center portion of the lower housing 44, and having a diameter equal to the inner diameter of the upper housing 46, the inside of the upper housing 46. And a lead wire 54 for outputting a signal detected by the microphone element 50. The weight 52 is fitted in the lower housing 44 and is sandwiched between the upper housing 46 side surface of the lower housing 44 and the upper housing 46.

The weight 52 functions as a sound insulation device in this embodiment, and like the sound insulation wall 16, a material having a relatively large specific gravity, or a sound absorbing material sandwiched between the materials having a relatively large specific gravity. With the sandwiched structure, the ambient sound propagating from the air to the heart sound microphone 12 is shielded to prevent the microphone element 50 from detecting the ambient sound.

The microphone element 50 is provided on the opposite side of the lower housing 44 from the fitting hole 48, that is, on the side in contact with the skin 14, and has a tapered hole 56 having a smaller diameter toward the fitting hole 48 side. Bottomed cylindrical microphone case 60 having a diaphragm housing chamber 58 opening at the bottom of the
And a diaphragm 62 which is housed in the diaphragm housing chamber 58 so as to divide the diaphragm housing chamber 58 into two parts in the axial direction and detects a heart sound, and the outer peripheral portion of the diaphragm 62 has both sides thereof. The air-conducting microphone is provided with a diaphragm holding device 64 that holds or holds so that the pressure becomes equal to. The diaphragm holder 64 holds a part of the entire circumference of the diaphragm 62, or forms a communication passage for communicating the chambers bisected by the diaphragm 62 even if the entire circumference is gripped. It is something to do. In addition, the diaphragm 6
The reference numeral 2 is composed of, for example, a piezoelectric ceramic plate, and outputs a heart sound signal SH from a pair of electrodes fixed to one surface thereof through a pair of lead wires 54.

FIG. 3 is a block diagram of a cancel sound signal output function of the high-speed arithmetic processing unit 26 in the heart sound detecting device 10 for outputting a cancel sound signal representing a cancel sound for processing the environmental sound and canceling the environmental sound. It is a functional block diagram explaining a part.

In FIG. 3, the output period determining means 70 is
The output period for outputting the pseudo environment sound signal SN _f to the external speaker 30 is determined. This output period is determined to be a predetermined period in which the intensity of the periodic heart sound signal SH output from the heart sound microphone 12 is minimized. Pseudo-environmental sound signal output means 7
2 is a preset pseudo-environmental sound signal S that represents a sound in a frequency band that interferes with the diagnosis when performing a diagnosis using a heart sound during the output period determined by the output period determining means 70.
Output N _f .

The signal processing condition determining means 74, in a state where a pseudo-environmental sound is generated from the external speaker 30, produces an environment that propagates to the heart sound microphone 12 based on the pseudo-environmental sound sequentially detected by the environmental sound microphone 20. A signal processing condition A for sequentially outputting a cancel sound signal SC representing a cancel sound for canceling a sound is determined. That is,
In a state where the pseudo environment sound is generated from the external speaker 30, the pseudo environment sound detected by the heart sound microphone 12 is minimized (that is, the heart sound signal SH from the heart sound microphone 12 is minimized). A signal processing condition A for sequentially outputting the cancel sound signal SC is determined.

The cancel sound signal SC is output to the cancel sound speaker 42 fixed to the inner surface of the bottom portion 18 of the sound insulation wall 16, and the cancel sound output from the cancel sound speaker 42 based on the cancel sound signal SC causes the heart sound. In order to cancel the pseudo-environmental sound detected by the microphone 12, it is desirable that the cancel sound has a phase opposite to that of the pseudo-environmental sound detected by the heart sound microphone 12 and has the same amplitude intensity as the pseudo-environmental sound. Here, the heart sound microphone 12
Since the weight 52 is provided inside the housing 47, the pseudo-environmental sound propagating through the air and directly to the housing 47 is blocked by the weight 52 and is not detected by the microphone element 50. However, a part of the pseudo-environmental sound propagates from the air to the skin 14 and is emitted again from the skin 14 via the living tissue. In this way, the pseudo environment sound emitted from the opening of the heart sound microphone 12 on the skin 14 side is detected by the microphone element 50.

Therefore, the cancel sound output from the cancel sound speaker 42 is the cancel sound.
At the time of propagating to the living body tissue below and interfering with the pseudo-environmental sound propagating in the living body tissue, the pseudo-environmental sound propagating in the living body tissue has the opposite phase and the same amplitude intensity. Sound is desirable. On the other hand, the external speaker 30
The pseudo ambient sound output from the ambient sound microphone 20 is also detected, and a part of the same sound as the pseudo ambient sound detected by the ambient sound microphone 20 (that is, a sound having the same phase and intensity) is propagated to the biological tissue. To do. Then, the pseudo environmental sound detected by the environmental sound microphone 20 is supplied to the high-speed processing unit 26 as the environmental sound signal SN _t .

Therefore, in the signal processing condition determining means 74,
The cancel sound signal SC is determined based on the sound obtained by inverting the phase of the pseudo environment sound detected by the environment sound microphone 20. However, the environmental sound signal SN _t output from the environmental sound microphone 20 is processed to output the cancel sound signal SC, and the cancel sound output from the cancel sound speaker 42 is the skin 14 or the skin based on the cancel sound signal SC. The phase and amplitude intensity of the pseudo-environmental sound change while propagating into the living tissue under 14. Since the speed at which the pseudo-environmental sound propagates in the living tissue differs for each living body or for each part of the living body, the changes in the phase and the amplitude intensity are different for each living body or each part of the living body. Therefore, the signal processing condition A for outputting the cancel sound signal SC is determined so that the heart sound signal SH from the heart sound microphone 12 becomes the smallest, that is, the pseudo environmental sound is most preferably canceled. is there. The signal processing condition A determined in this manner is a sound in which the pseudo-environmental sound is preset as a sound in a frequency band that interferes with the diagnosis, and thus the frequency band that interferes with the diagnosis can be canceled most effectively. It is the signal processing condition A capable of outputting a possible cancel sound.

The environmental sound processing means 76 also functions as a cancel sound signal determining means, and the external speaker 3
Processing the environmental sound signal SN _t sequentially output from the environmental sound microphone 20 based on the signal processing condition A determined by the signal processing condition determining means 74 in a state where no pseudo environmental sound is generated from 0. The cancel sound signal SC is sequentially determined by. When the cancel sound signal SC is determined and the cancel sound is output from the cancel sound speaker 42 based on the cancel sound signal, the cancel sound is propagated in the living tissue and propagated in the living tissue, particularly the environmental sound propagated in the living tissue. It is possible to cancel the sound in the frequency band that interferes with the diagnosis of heart sounds.

FIGS. 4 and 5 are flowcharts for explaining the main part of the cancel sound output function of the high-speed arithmetic processing unit 26. FIG. 4 processes the environmental sound signal SN _t output from the environmental sound microphone 20. 5 is a signal processing condition determination routine for determining the signal processing condition A to be performed. FIG. 5 is an environmental sound processing for processing the environmental sound output from the environmental sound microphone 20 under the signal processing condition A and outputting the cancel sound signal SC. It is a routine.

In the signal processing condition determining routine shown in FIG. 4, first, step S corresponding to the output period determining means 70.
A1 (hereinafter, steps are omitted) to SA6 are executed. First, in SA1, the heart sound signal SH output from the heart sound microphone 12 is read, and in the subsequent SA2,
The heart sound signal SH for a predetermined number of beats is detected by detecting a cyclically repeating predetermined portion of the heart sound, for example, the peak of the I sound.
Is read. The above specified number of beats is
In order to determine the heartbeat cycle T _h , it is preset to several to several tens of beats.

While the determination of SA2 is denied, S
By repeatedly executing A1 and thereafter, the heart sound signal S
Reading of H is continued. However, when the determination in SA2 is affirmative, in subsequent SA3, the heartbeat cycle _Th is determined based on the heart sound signal SH read in SA1.

In subsequent SA4 to SA6, it is judged whether or not it is time to start outputting the pseudo environment sound signal SN _f . First, in SA4, it is determined whether or not the I sound of the heart sound is detected. While this judgment is denied, SA4
Is repeatedly executed, but if it is affirmed, the subsequent SA
5, the content of the timer t is cleared, and at SA6, whether the timer t exceeds the value obtained by subtracting a preset value α of about 0.2 seconds from the heartbeat cycle T _h determined at SA3. To be judged. As shown in the diagram characteristically showing the normal heart sound waveform of FIG. 6, there are normal heart sounds I to IV in the heart sounds. When there is a heart disease, a heart murmur is generated together with the I sound or the II sound. That is, when there is a heart disease, the murmur waveform may be included in the predetermined section after the I sound is generated and the predetermined section after the II sound is generated. Therefore, a predetermined period α before the I sound is generated, that is, after (T _h −α) time has elapsed after the I sound is generated, is defined as a section having the smallest heart sound signal SH, and after the I sound is generated (T _The time point when _h- α) has elapsed is the time when the output of the pseudo environment sound signal SN _f is started.

In the subsequent SA7 corresponding to the pseudo environment sound signal output means 72, a preset pseudo environment sound signal SN _f representing a sound in a frequency band which interferes with the diagnosis in outputting a heart sound is output. Then, the external speaker 30 generates a pseudo environmental sound represented by the pseudo environmental sound signal SN _f .

Then, SA8 to SA12 corresponding to the signal processing condition determining means 74 are executed to process the environmental sound signal SN _t output from the environmental sound microphone 20 and sequentially output the cancel sound signal SC. Signal processing condition A is determined.

First, at SA8, the environmental sound microphone 20 detects a pseudo environmental sound, and the environmental sound signal SN _t output from the environmental sound microphone 20 is sequentially read at the sampling cycle T _S. In the subsequent SA9, the environmental sound signal SN _t sequentially read in SA8 is processed by the preset reference signal processing condition A ₀ or the signal processing condition A updated in SA11 described later, and the cancel sound signal SC is sequentially processed. Is output. At SA10, the heart sound signal SH output from the heart sound microphone 12 is read. That is, the heart sound signal SH output from the heart sound microphone 12 in a state where the pseudo environment sound and the cancel sound are generated.
Is read.

In the subsequent SA11, the preset reference signal processing condition A ₀ or the signal processing condition A updated by executing the previous SA11 is executed based on the heart sound signals SH sequentially read in SA10. , The heart sound microphone 12 by a learning identification method (NLMS method) generally used in an active noise control system.
The heart sound signal SH output from is updated so as not to be small.

At SA12, the contents of the timer t are
At SA7, the pseudo environment sound signal SN _fIs output
, The maximum time preset as the time less than or equal to the predetermined period α
Whether or not the optimization period β has elapsed, that is, within the timer t
Yong (T_h-Α + β) is exceeded. This
If the determination is positive, this routine ends, and as shown in FIG.
The environmental sound processing routine shown is executed. But S
While the determination of A12 is denied, the above SA7 and later are repeated.
By being executed again, the simulated environmental sound signal SN_fBut
Output, environmental sound signal SN_tAnd body sound signal is read
In rare cases, optimization of the signal processing condition A is continued.

Next, the environmental sound processing routine of FIG. 5 will be described. First, in SB1, the contents of the timer t are cleared, and in the subsequent SB2, the environmental sound signal SN _t output from the environmental sound microphone 20 is sequentially read at the sampling cycle T _S.

SB3 corresponding to the subsequent environmental sound processing means 76
Then, the environmental sound signal SN _t read in SB2 is processed under the signal processing condition A determined to be the optimum condition in SA11 of FIG. 4, and is output as the cancel sound signal SC.

At the subsequent SB4, it is determined whether or not a preset measurement period γ has elapsed. While the determination of SB4 is denied, the above SB2 and the following steps are executed to sequentially cancel the cancel sound signal S from the environmental sound signal SN _t.
C is determined and output. However, if the determination at SB4 is affirmative, it means that the measurement of the heart sounds has ended, and therefore this routine is ended.

As described above, according to the present embodiment, the environmental sound propagating directly from the air to the housing 47 has the weight 52.
Is blocked by the microphone element 50 and is not detected by the microphone element 50. Since the environmental sound microphone 20 is provided above the heart sound microphone 12 and at a position separated from the skin 14 by a predetermined distance, the environmental sound microphone 20 sequentially detects the environmental sound, and the cancel sound signal output device 27. Then, in the signal processing condition determining means 74 (SA8 to SA12), the pseudo environment sound detected by the heart sound microphone 12 is minimized in the state where the pre-stored pseudo environment sound is generated from the external speaker 30. , Environmental sound microphone 20
Based on the pseudo-environmental sounds that are sequentially detected in the
In the state where the signal processing condition A for sequentially outputting the cancel sound signal SC representing the cancel sound for canceling the environmental sound propagating to 2 is determined, and the pseudo environmental sound is not generated from the external speaker 30, the environmental sound is generated. Processing means 76
By (SB3), the signal processing condition determining means 74 (SA8)
Through SA12), the environmental sound detected by the environmental sound microphone 20 is processed based on the signal processing condition A determined in S12) to sequentially determine the cancel sound signal SC, and based on the cancel sound signal SC, the environmental sound microphone 20 Since the cancel sound is output from the cancel sound speaker 42 provided at a position closer to the heart sound microphone 12, the environmental sound propagating in the living tissue is canceled by the cancel sound. Therefore, the vibrating plate 62 of the microphone element 50 is suppressed from being vibrated by the environmental sound emitted from the skin 14 again via the living tissue, so that the heart sound signal SH with less environmental sound is obtained.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other modes.

For example, in the above-described embodiment, the weight 52 provided in the housing 47 functions as a sound insulation device, but the housing 47 itself is made of the same material as the weight 52 and functions as a sound insulation device. Alternatively, a closed air chamber may be provided on the outer peripheral side of the microphone element 50 in the housing 47, and the air chamber may function as a sound insulation device. In short, the environmental sound that propagates directly from the air to the housing 47 is isolated,
Anything that prevents the microphone element 50 from detecting it may be used.

Further, in the above-described embodiment, the heartbeat period T is detected by detecting a predetermined portion of the heart sound that periodically repeats.
_{Although h} has been determined and the content of the timer t has been cleared, an electrocardiographic induction device for measuring an electrocardiogram is provided, and a predetermined part of the electrocardiographic induction waveform output from the electrode of the electrocardiographic induction device ( For example, the R wave) may be used to determine the heartbeat cycle T _h , and the content of the timer t may be cleared.

Further, in the above-described embodiment, the signal processing condition determining means 74 (SA8 to SA13) is executed and the signal processing condition A is optimized in the predetermined period in which the intensity of the heart sound signal SH is minimized. However, the signal processing condition A is determined so that the heart sound signal SH is minimized even in other periods, that is, periods in which heart sounds such as I sound and II sound occur or heart noise occurs. As a result, the signal processing condition A is temporarily determined to be the optimum value, and therefore the signal processing condition determining means 74 (SA8 to SA13).
Does not have to be performed during the predetermined period when the intensity of the heart sound signal SH becomes the smallest.

Further, in the above-described embodiment, the optimization of the signal processing condition A in SA11 of the signal processing condition determination routine of FIG. 4 is completed within the preset optimization period β. That is, although the process ends in one beat, the optimization of the signal processing condition A may be executed between the predetermined number of beats of two or more. Alternatively, it may be determined whether or not the signal processing condition A has converged to a constant value, and the optimization may be terminated when the signal processing condition A converges to a constant value.

In addition, the present invention can be modified in various ways without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a heart sound detection device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the configuration of the heart sound microphone of FIG.

FIG. 3 is a functional block diagram illustrating a main part of a cancel sound signal output function for outputting a cancel sound signal of the high-speed arithmetic processing device.

FIG. 4 is a flowchart illustrating a main part of control operation of the high-speed arithmetic processing device according to the embodiment of FIG. 1, and is a diagram illustrating a signal processing condition determination routine.

5 is a flowchart illustrating a main part of control operation of the high-speed arithmetic processing apparatus according to the embodiment of FIG. 1, and is a diagram illustrating an environmental sound processing routine.

FIG. 6 is a diagram showing a normal heart sound waveform.

[Explanation of sign]

10: Heart sound detector 12: Heart sound microphone (living sound microphone) 20: Environmental sound microphone 27: Cancel sound signal output device 30: External speaker (pseudo environmental sound generator) 42: Cancel sound speaker 46: Housing 50: Microphone element 52: Weight (sound insulation device) 62: diaphragm 74: Signal processing condition determining means 76: Environmental sound processing means

Claims (2)

[Claims] 1. A body sound detection device equipped with a body sound microphone that is mounted on the skin of a body, detects body sound generated in the body, and outputs a body sound signal representing the body sound. An environmental sound microphone provided above the biological sound microphone and spaced apart from the skin of the biological body by a predetermined distance to sequentially detect environmental sound around the biological sound detection device, and the environmental sound microphone sequentially. A cancel sound signal that is the same as the environmental sound that is sequentially detected by the environmental sound microphone and that represents a cancel sound for canceling the environmental sound that propagates to the biological sound microphone based on the detected environmental sound. A cancel sound signal output device to be output, and a cancel sound signal output from the cancel sound signal output device, provided at a position where the distance between the environmental sound microphone and the living body sound microphone is shorter than that of the environmental sound microphone. A living body sound detection device comprising: a cancellation sound speaker that outputs a cancellation sound. 2. A housing which is opened in one direction and whose opening side is brought into close contact with a living body, and a microphone element which has a diaphragm and is provided in the housing, and which converts the vibration of the diaphragm into an electric signal. A body sound detection device comprising a body sound microphone having the body sound detector, which is mounted on the skin of the body and detects a body sound generated in the body, and outputs a body sound signal representing the body sound from the body sound microphone. A sound insulation device provided in the body sound microphone on the outer peripheral side of the body sound microphone with respect to the microphone element, and a position above the body sound microphone and separated from the skin of the body by a predetermined distance. An environmental sound microphone that sequentially detects environmental sounds around the biological sound detection device, a pseudo-environmental sound generation device that generates a pre-stored pseudo-environmental sound, and a pseudo-environmental sound generation device In a state where a boundary sound is being generated, a cancel sound signal representing a cancel sound for canceling the environmental sound propagating to the biological sound microphone is sequentially generated based on the pseudo environmental sound sequentially detected by the environmental sound microphone. A signal processing condition determining means for determining a signal processing condition for outputting, and a signal processing condition determined by the signal processing condition determining means in a state in which a pseudo environment sound is not generated from the pseudo environment sound generating device. A cancel sound signal output device including an environmental sound processing unit that determines the cancel sound signal by processing the environmental sound detected by the environmental sound microphone based on the living body sound microphone; Is provided at a position where the distance is short, and a cancel sound is generated based on the cancel sound signal output from the cancel sound signal output device. A canceling sound speaker for force, biological sound detection device, which comprises.