JP2019000520A - Biological sound measurement system and calibration method of the measurement data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily calibrate a measurement data of a biological sound in a biological sound measuring system. SOLUTION: A monitoring side unit for measuring a biological sound of a subject 2 by detecting a change in the internal pressure of the external auditory canal 2a by a pressure sensor 20 in a state where a sensor unit 10 is attached to the external auditory canal 2a of the subject 2. The configuration is provided with 110. At that time, the sensor unit 10 is provided with a speaker 50 capable of outputting an acoustic signal to the ear canal 2a. Further, as the monitoring side unit 110, a composite sound in which the first and second pure tones having different frequencies are combined is output as a calibration sound from the speaker 50 to the ear canal 2a, and the change in the internal pressure of the ear canal 2a due to the output of the calibration sound is output. It is configured to calibrate the measurement data by using it. This simplifies the calibration work by eliminating the need to use a coupler to set the reference level as in the past. [Selection diagram] Fig. 1

Description

  The present invention relates to a body sound measurement system configured to measure a body sound of a subject and a method for calibrating the measurement data.

  2. Description of the Related Art Conventionally, a medical device or a health management device that includes a biological sound measurement system for measuring a biological sound of a subject is known.

  Further, as such a body sound measurement system, by detecting a change in internal pressure of the ear canal with the pressure sensor in a state where a sensor unit including a pressure sensor is attached to the patient's ear canal, Those configured to measure are known.

  In “Patent Document 1”, as such a body sound measurement system, an ear tip that constitutes a part of a sensor unit is inserted into the ear canal of a subject, and the jugular vein pressure is measured as the body sound. It has been described.

  Further, in “Patent Document 2”, the sensor unit used in the body sound measurement system is configured to include not only the pressure sensor but also a speaker capable of outputting an acoustic signal to the ear canal, and the pressure sensor changes the internal pressure of the ear canal. Is detected, a pure tone is output as a calibration sound from the speaker to the ear canal, and the measurement data is calibrated using the change in the internal pressure of the ear canal due to the output of the calibration sound.

  In the calibration method described in “Patent Document 2”, a coupler having substantially the same volume as the ear canal is prepared, and a calibration sound is output from the speaker in a state where a sensor unit is attached to this coupler to form a completely sealed space. The amplitude of the calibration sound detected by the pressure sensor is set as a reference level, and a change in the internal pressure of the ear canal is preliminarily detected while the sensor unit is intentionally attached to the ear canal in a manner that causes air leakage. The preliminary operation is performed a plurality of times while repeatedly attaching and detaching the sensor unit so as to include the first time region in which the calibration sound is output from the speaker and the second time region in which the calibration sound is not output from the speaker. From the calibration sound and biological sound detected by the preliminary operation, the attenuation amount from the reference level of the amplitude of the calibration sound and the corresponding attenuation amount of the amplitude of the biological sound Create a characteristic curve showing the relationship, so as to calibrate the measured data based on the characteristic curve.

Japanese Patent No. 5585955 JP 2017-42232 A

  By adopting the biological sound measurement system described in the above-mentioned “Patent Document 2”, even if some air leakage occurs when the sensor unit is attached to the ear canal, the measurement data is calibrated by outputting the calibration sound from the speaker. It is possible to appropriately measure the body sound.

  However, in the biological sound measurement system described in the above-mentioned “Patent Document 2”, it is necessary to prepare a coupler for setting the reference level when calibrating measurement data, so that the calibration work is complicated. End up.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a biological sound measurement system that can easily calibrate measurement data of a biological sound and a calibration method of the measurement data. To do.

  In the present invention, a speaker unit is provided as a sensor unit, and a predetermined composite sound is used as a calibration sound output from the speaker to the ear canal so as to achieve the above object.

That is, the body sound measurement system according to the present invention is:
A living body configured to measure a body sound of the subject by detecting a change in internal pressure of the ear canal with the pressure sensor in a state where a sensor unit including a pressure sensor is attached to the ear canal of the subject. In the sound measurement system,
A monitoring-side unit that performs processing for measuring the body sound using the detection result of the internal pressure change;
The sensor unit includes a speaker capable of outputting an acoustic signal to the ear canal,
The monitoring side unit outputs a composite sound in which the first and second pure sounds having different frequencies are combined as calibration sound from the speaker to the ear canal, and uses the change in internal pressure of the ear canal due to the output of the calibration sound. It is configured to calibrate the measurement data.

  The specific configuration of the “pressure sensor” is not particularly limited as long as it can detect a change in internal pressure generated in the ear canal.

  If the “calibration sound” is a composite sound in which the first and second pure sounds having different frequencies are combined, the specific frequency and amplitude of each of the first and second pure sounds are not particularly limited. Absent.

  The living body sound measurement system according to the present invention is a monitoring-side unit that measures a body sound of a subject by detecting a change in internal pressure of the ear canal with the pressure sensor in a state where the sensor unit is mounted on the ear canal of the subject. However, the sensor unit includes a speaker capable of outputting an acoustic signal to the ear canal, and the monitoring side unit outputs first and second pure sounds having different frequencies as calibration sounds from the speaker to the ear canal. Since the composite sound is output and the measurement data is calibrated by using the change in the internal pressure of the ear canal due to the output of the calibration sound, the following operational effects can be obtained.

  That is, even if some air leakage occurs when the sensor unit is attached to the ear canal, the measurement of the biological data can be properly performed by calibrating the measurement data by the output of the calibration sound from the speaker. At that time, since the composite sound in which the first and second pure tones having different frequencies are combined is output as the calibration sound, the calibration is performed by using these two pure tones as in the conventional case. The need to use a coupler for setting the reference level can be eliminated, thereby simplifying the calibration operation.

  As described above, according to the present invention, the measurement data of the body sound can be easily calibrated in the body sound measurement system.

  In the biological sound measurement system, the following method can be employed as a specific method for calibrating measurement data of biological sound.

  That is, from the frequency spectrum of the internal pressure change of the external auditory canal detected by the pressure sensor when the calibration sound is output from the speaker to the external ear canal, the amplitude of the internal pressure change at the frequency of the first pure tone and the amplitude of the internal pressure change at the frequency of the second pure sound It is possible to employ a method of calculating the difference between the two as a difference level and calibrating the measurement data based on the difference level.

  By adopting such a calibration method, the following effects can be obtained.

  That is, as the air leak from the ear canal increases, the amplitude of the change in internal pressure is more greatly attenuated in the low frequency region. Therefore, as the air leak from the ear canal increases, the difference level increases. Therefore, by calibrating the measurement data for air leakage from the ear canal based on the difference level, it is possible to perform appropriate calibration without using a coupler for setting the reference level as in the prior art.

  Moreover, the following effects can also be obtained by adopting the calibration method of the present invention.

  That is, in the conventional calibration method, when the measurement data is calibrated, the amplitude of the calibration sound detected in the coupler is set to a reference level. In such a calibration method, the size of the ear canal of the subject is determined. Individual differences are not considered. Therefore, in the case of a subject whose volume of the ear canal is larger than the volume of the coupler, the amplitude of the calibration sound detected at this time is the calibration sound detected in the coupler, even if the sensor unit is sealed. May become smaller than the amplitude of the air and it may be determined that there is an air leak.

  In that respect, in the calibration method of the present invention, the measurement data can be calibrated with the sensor unit attached to the ear canal without using a coupler. Good measurements can be made.

  In the calibration method of the present invention, if a pure tone in a non-audible frequency range lower than the audible frequency range is used as the first pure tone, and a pure tone in the audible frequency range is used as the second pure tone, the following operation is performed. An effect can be obtained.

  That is, when a single pure tone is used as the calibration sound as in the past, if the frequency of the calibration sound is far away from the frequency of the body sound, the effect of air leakage from the external auditory canal on the measurement data can be accurately measured. It becomes difficult to evaluate. On the other hand, if a pure tone in a non-audible frequency region lower than the audible frequency region is used as the calibration sound, the calibration sound cannot be heard by the subject, so that it is difficult to perform the calibration work smoothly.

  On the other hand, by using a pure tone in the non-audible frequency range lower than the audible frequency range as the first pure tone, the frequency of the calibration sound can be brought close to the frequency of the biological sound, so that air leakage from the ear canal is measured data. Therefore, it is possible to easily evaluate the influence on the measurement data, thereby improving the calibration accuracy of the measurement data. Further, by using a pure tone in the audible frequency region as the second pure tone, the calibration sound can be heard by the subject, so that the calibration operation can be performed smoothly.

  At that time, if the amplitude ratio between the first pure tone and the second pure tone is set to a value of twice or more, the following effects can be obtained.

  That is, when a pure tone in a non-audible frequency range lower than the audible frequency range is used as the first pure tone, the amplitude of the biological sound existing near the frequency of the first pure tone is large. It is not easy to secure S / N when performing. On the other hand, if the amplitude of the second pure tone in the audible frequency region is increased, there is a possibility that the subject may feel uncomfortable during the calibration work. Therefore, by setting the amplitude ratio between the first pure tone and the second pure tone to a value that is twice or more, the S / N when performing calibration without causing discomfort to the subject. Can be secured.

  The following method can be employed as the calibration method of the present invention.

  That is, the sensor unit is attached to the ear canal in a plurality of modes with different levels of air leakage to detect the frequency spectrum, and detection is performed in the presence of air leakage with respect to the frequency spectrum detected with almost no air leakage. A correction curve indicating the correction amount of the amplitude of the body sound according to the frequency is created from the amplitude attenuation amount in the frequency spectrum and the difference level in each frequency spectrum, and the body sound is calculated based on the correction curve. It is possible to employ a method in which a waveform obtained by adding a correction amount for each frequency to the waveform is used as measurement data of biological sound.

  When such a calibration method is adopted, it is necessary to perform the same operation as the conventional preliminary operation, but by adopting such a calibration method, the measurement data of the living body sound has an appropriate waveform shape. Can be calibrated to approach

  At this time, if the correction curve is approximated by a polygonal line, the calibration for approximating the waveform of the measurement data of the body sound to an appropriate shape can be performed by dividing it into a plurality of frequency regions by a simple calculation process. .

Configuration schematic diagram showing a body sound measurement system according to an embodiment of the present invention Block diagram showing the biological sound measurement system Side sectional view showing a sensor unit of the biological sound measurement system The figure which shows the measurement procedure of the body sound in the said body sound measurement system The figure which shows the waveform of the calibration sound output from the speaker of a sensor unit, when calibrating the measurement data of the said body sound Diagram showing the frequency spectrum of the calibration sound Diagram showing waveforms of calibration sound and body sound collected with some air leakage The figure which shows the frequency spectrum of the above-mentioned calibration sound and body sound Diagram showing correction curve for calibration FIG. 8 shows the frequency spectrum shown in FIG. 8 together with the frequency spectrum obtained under different measurement conditions. Diagram showing the frequency spectrum used to obtain the correction curve The figure which shows the measurement data calibrated by the above correction curve together with the measurement data before calibration and the measurement data when there is almost no air leakage

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a biological sound measurement system 100 according to an embodiment of the present invention, and FIG. 2 is a block diagram thereof.

  As shown in FIG. 1, the body sound measurement system 100 includes a sensor unit 10 and a monitoring unit 110, and is configured to be able to perform transmission / reception by wireless communication between the two.

  And in this biological sound measuring system 100, by detecting the internal pressure change of the external auditory canal 2a in a state where the sensor unit 10 is attached to the external auditory canal 2a of the subject 2, the pulse sound of the subject 2 is used as the biological sound. It comes to measure.

  The monitoring side unit 110 is configured by a smartphone (or a personal computer or the like), receives a detection signal of a biological sound transmitted from the sensor unit 10, and performs data processing necessary for measurement of the biological sound and calibration of the measurement data. Is supposed to do.

  First, the configuration of the sensor unit 10 will be described.

  FIG. 3 is a side sectional view showing the sensor unit 10.

  As shown in the figure, the sensor unit 10 includes a housing 12 in which a sound guide hole 12a is formed at a front end portion (right end portion in FIG. 3), a pressure sensor 20 and a speaker 50 housed in the housing 12. And an ear tip 16 attached to the front end of the housing 12.

  The sensor unit 10 picks up a biological sound generated as a change in the internal pressure of the ear canal 2a by the pressure sensor 20 in a state where the ear tip 16 is inserted into the ear canal 2a of the subject 2.

  The housing 12 has a configuration in which a front member 12A and a rear member 12B are joined. The internal space C of the housing 12 is configured as a sealed space except for the sound guide hole 12a.

  A gasket 18 having a cylindrical outer peripheral surface is disposed at the front end portion of the internal space C of the housing 12. The gasket 18 is inserted to a position where the front end surface of the gasket 18 comes into contact with the front end wall 12Aa of the front member 12A in a state where the outer peripheral surface is fitted into the small diameter portion of the inner peripheral surface of the front member 12A from the rear side. Yes.

  The gasket 18 has a front half formed in a cylindrical shape and a rear half formed in a columnar shape, and a first and second through-hole 18a extending in the front-rear direction with a circular cross-sectional shape at the center of the rear half. , 18b are formed at intervals in the vertical direction. The first and second through holes 18a and 18b allow the internal space C of the housing 12 to communicate with the sound guide hole 12a.

  In the internal space C of the housing 12, the pressure sensor 20 is disposed behind the speaker 50. A signal processing circuit unit 60 is arranged alongside the pressure sensor 20 at a position behind the speaker 50 in the internal space C, and a battery 70 is arranged behind the signal sensor circuit unit 60.

  The signal processing circuit unit 60 has an antenna function, and is configured to be able to transmit and receive with the monitoring unit 110 (see FIG. 1). The battery 70 is configured to supply power to the pressure sensor 20, the speaker 50, and the signal processing circuit unit 60.

  The speaker 50 is a balanced armature type speaker, and has a configuration in which a diaphragm and a drive unit (not shown) are accommodated in a housing 52.

  The speaker 50 is positioned in a state where the tip of the sound emitting nozzle 54 is inserted into the second through hole 18b of the gasket 18 from the rear side. The speaker 50 generates a sound wave corresponding to the signal current from the signal processing circuit unit 60 and radiates the sound wave to the sound guide hole 12a through the sound emission hole 52a and the second through hole 18b. It has become.

  A cylindrical member 28 extending in the front-rear direction is disposed below the speaker 50 in the internal space C of the housing 12. The front end portion of the cylindrical member 28 is inserted into the first through hole 18 a of the gasket 18. The tubular member 28 is formed so as to extend further to the rear than the speaker 50.

  The pressure sensor 20 is a small electret condenser microphone, and includes a diaphragm 22 and a housing 24 configured to form a front space Cf and a back space Cr on both front and rear sides of the diaphragm 22.

  The housing 24 is formed with a sound collection hole 24 a and a vent hole 24 b that allow the front space Cf and the back space Cr to communicate with the external space of the housing 24. A sound collecting nozzle 26 formed so as to surround the sound collecting hole 24a is attached to the housing 24 by welding or the like.

  The pressure sensor 20 is disposed along a vertical plane orthogonal to the front-rear direction, and is connected to the rear end portion of the tubular member 28 at the sound collection nozzle 26. This connection is performed by inserting the front end of the sound collection nozzle 26 into the rear end of the tubular member 28.

  As a result, the internal space C of the housing 12 is partitioned into a first space C1 communicating with the front space Cf and the sound guide hole 12a and a second space C2 communicating with the back space Cr.

  The ear tip 16 is made of a soft material such as silicone rubber.

  A through-hole 16 a that penetrates the ear tip 16 in the front-rear direction is formed at the center of the ear tip 16. The through hole 16a communicates with the sound guide hole 12a in a state where the ear tip 16 is attached to the small diameter cylindrical portion 12Ab. The through hole 16a is formed with a smaller diameter than the sound guide hole 12a.

  The eartip 16 includes two front and rear flange portions 16A and 16B that spread in a substantially parabolic shape toward the rear side. At that time, the flange portion 16B on the rear side is formed with a larger diameter than the flange portion 16A on the front side. Thus, when the ear tip 16 is properly inserted into the ear canal 2a, the two front and rear flange portions 16A and 16B are in close contact with the wall surface of the ear canal 2a, and are sealed in the ear canal 2a by the ear canal wall, the eardrum and the ear tip 16. A space is formed.

  In this sealed external ear canal 2a, vibrations of the ear canal wall and the eardrum caused by the pulse of the subject 2 are radiated. At this time, a pulse sound generated as a change in the internal pressure of the external ear canal 2a is collected by the pressure sensor 20 as a living body sound. It will be sounded.

  Next, the configuration of the monitoring unit 110 will be described.

  As shown in FIG. 2, the monitoring side unit 110 includes a CPU 112, a memory 114 connected to the CPU 112, and a display 116.

  The CPU 112 is configured to be able to transmit / receive to / from the sensor unit 10, and processes data of the internal pressure change of the external auditory canal 2 detected by the pressure sensor 20 and outputs an acoustic signal to the external auditory canal via the speaker 50. ing.

  The memory 114 stores, as calibration sound data, composite sound data in which the first and second pure sounds are combined, and calibration curve data for calibration.

  The display 116 displays biological sound measurement data, operation procedures for the measurement, and the like.

  FIG. 4 is a diagram illustrating a procedure for measuring a body sound in the body sound measurement system 100.

  First, the sensor unit 10 is attached to the ear canal 2a of the subject 2 (step S1).

  This mounting is performed by inserting the ear tip 16 of the sensor unit 10 into the ear canal 2a.

  Next, as a calibration sound for calibrating the measurement data of the body sound from the speaker 50 to the ear canal 2a, a composite sound in which the first and second pure sounds having different frequencies are combined for a certain period of time (for example, about 15 seconds). ) Is output (step S2).

  At that time, a 10 Hz pure tone (that is, a pure tone in a non-audible frequency range lower than the audible frequency range) is used as the first pure tone, and a 30 Hz pure tone (that is, a pure tone in the audible frequency range) is used as the second pure tone. Further, the amplitude ratio between the first pure tone and the second pure tone is set to a value that is twice or more (for example, a value that is about three times).

  FIG. 5 is a diagram showing a waveform of the calibration sound output at this time, and FIG. 6 is a diagram showing a frequency spectrum of the calibration sound.

  Next, a change in the internal pressure of the ear canal 2a that occurs at this time is detected by the pressure sensor 20 (step S3).

  The change of the internal pressure is detected by collecting the calibration sound and the biological sound over a longer time (for example, about 30 seconds) than the time during which the calibration sound is output.

  FIG. 7 is a diagram illustrating waveforms of the calibration sound and the body sound collected at this time (that is, a waveform of a change in internal pressure of the ear canal 2a).

  In addition, in the same figure, the example of sound collection in case there exists some air leaks from the ear chip | tip 16 of the sensor unit 10 with which the ear canal 2a was mounted | worn is shown.

  Next, frequency analysis of the internal pressure change is performed for a certain time (for example, about 10 seconds) in the time zone in which the calibration sound is output (step S4).

  FIG. 8 is a diagram showing the result of this frequency analysis as a frequency spectrum.

  In this frequency spectrum, the peak of the amplitude of the internal pressure change appears at the frequency of the first pure tone (10 Hz) and the frequency of the second pure tone (30 Hz).

  Next, from this frequency spectrum, the difference (A1-A2) between the amplitude A1 of the internal pressure change at the frequency of the first pure tone (10 Hz) and the amplitude A2 of the internal pressure change at the frequency of the second pure tone (30 Hz) is obtained as a differential level. It calculates as (DELTA) A (step S5).

  Next, from this difference level ΔA, a correction curve L1 indicating the correction amount of the biological sound waveform is derived (step S6).

  As shown in FIG. 9, the correction curve L1 is composed of a broken line in which a frequency region of 0.1 to 25 Hz is divided into four bands, and correction amounts y1 to y4 represented by the following formulas are assigned to the respective bands. Has been.

In particular,
In the 0.1-5 Hz band,
y1 = −1.5x + {(− ΔA + 1.5) × 4 + 3 + ΔA} [dB]
In the 5-10 Hz band,
y2 = −1.5 × 5 + {(− ΔA + 1.5) × 4 + 3 + ΔA} [dB]
In the 10-15 Hz band,
y3 = − (y2 / 5) x + 3 × y2 [dB]
In the 15-25 Hz band,
y4 = 0 [dB]
Is set to

  In the above equations, x is a frequency [Hz], and y1 to y4 are correction amounts [dB].

  Next, based on the correction curve L1, a waveform obtained by adding a correction amount for each frequency to the waveform of the body sound is set as measurement data of the body sound (step S7).

  The correction curve L1 used in the measurement procedure is created in advance by measuring a body sound in an individual different from the subject 2, and the data is stored in the memory 114 of the monitoring unit 110. ing.

  Then, the CPU 112 of the monitoring side unit 110 performs digital filter processing on the digital electrical signal received from the sensor unit 10 to perform filtering such that the correction amount is added for each frequency, thereby measuring. The data is calibrated.

  The procedure for creating the correction curve L1 is as follows.

  First, the sensor unit 10 is attached to the ear canal 2a in three modes having different degrees of air leakage, and frequency spectra are detected respectively.

  Specifically, the external auditory canal 2a is substantially sealed so that almost no air leakage occurs (hereinafter referred to as “substantially sealed state”), and is loosely mounted so as to cause some air leakage (hereinafter referred to as “relaxed mounting state”). ") And a state in which a large amount of air leakage occurs and sound is leaking (hereinafter referred to as" sound leakage state ").

  FIG. 10 is a diagram showing the three frequency spectra S0, S1, and S2 obtained in this manner.

  In the figure, the curve indicated by the thick solid line is the frequency spectrum S0 in the “substantially sealed state”, the curve indicated by the slightly thick solid line is the frequency spectrum S1 in the “loosely attached state”, and the curve indicated by the thin solid line is “ It is the frequency spectrum S2 in the “sound leakage state”.

  In addition, the graph shown with a broken line in the same figure is a frequency spectrum in the case of only a body sound (when a calibration sound is not output).

  Next, FIG. 11A shows the attenuation of the amplitudes of the frequency spectra S1 and S2 detected in the “relaxed wearing state” and the “sound leakage state” with respect to the amplitude of the frequency spectrum S0 detected in the “substantially sealed state”. As shown in FIG. 11B, approximate curves At1a and At2a of the attenuation spectra At1 and At2 as shown in FIG. 11B are obtained.

  Based on the relationship between these two approximate curves At1a and At2a and the difference levels ΔA0, ΔA1 and ΔA2 in the frequency spectra S0, S1 and S2 shown in FIG. 10, the difference level ΔA is expressed as shown in FIG. A correction curve L1 is created as a broken line displayed by the four equations y1 to y4 used as parameters.

In FIG. 10, the specific values of the difference levels ΔA0, ΔA1, and ΔA2 are
ΔA0 = (− 24.8) − (− 26.0) = 1.2 [dB]
ΔA1 = (− 31.4) − (− 29.7) = − 1.7 [dB]
ΔA2 = (− 39.6) − (− 33.9) = − 5.7 [dB]
It is.

  FIG. 12 is a diagram showing measurement data of a biological sound that has been calibrated by adding a correction amount based on the correction curve L1, together with measurement data before calibration and measurement data when there is almost no air leakage.

  The measurement data shown in FIG. 5A is measurement data in a “substantially sealed state”.

  The measurement data shown in (b1) of the figure is measurement data before calibration in the “relaxed state”, and the measurement data shown in (b2) is measurement data after calibration in the “loose state”.

  The measurement data shown in (c1) of the figure is measurement data before calibration in the “sound leakage state”, and the measurement data shown in (c2) of the figure is measurement data after calibration in the “sound leakage state”.

  As shown in FIGS. 2B and 2C, the waveform of the body sound is obtained by calibrating the measurement data even in the “loosened state” or “sound leakage state”. ), Which is close to the characteristics of the waveform of the body sound measured in the “substantially sealed state” (that is, the maximum amplitude, fine peak shape, etc. are approximated).

  Next, the effect of this embodiment is demonstrated.

  The biological sound measurement system 100 according to the present embodiment detects a change in internal pressure of the ear canal 2a by the pressure sensor 20 in a state where the sensor unit 10 is mounted on the ear canal 2a of the subject 2, thereby Although the monitoring unit 110 for measuring a body sound is provided, the sensor unit 10 includes a speaker 50 capable of outputting an acoustic signal to the ear canal 2a, and the monitoring unit 110 is calibrated from the speaker 50 to the ear canal 2a. Since a composite sound in which the first and second pure sounds having different frequencies are combined is output as the sound, and the measurement data is calibrated by utilizing the change in the internal pressure of the ear canal 2a due to the output of the calibration sound. The following effects can be obtained.

  That is, even if some air leakage occurs when the sensor unit 10 is attached to the external auditory canal 2a, it is possible to appropriately measure the body sound by calibrating the measurement data by the output of the calibration sound from the speaker 50. . At that time, since the composite sound in which the first and second pure tones having different frequencies are combined is output as the calibration sound, the calibration is performed by using these two pure tones as in the conventional case. The need to use a coupler for setting the reference level can be eliminated, thereby simplifying the calibration operation.

  As described above, according to the present embodiment, the biological sound measurement system 100 can easily calibrate the measurement data of the biological sound.

  Moreover, in the present embodiment, the amplitude A1 of the internal pressure change at the frequency of the first pure sound and the first amplitude are obtained from the frequency spectrum of the internal pressure change of the external ear canal 2a detected by the pressure sensor 20 when the calibration sound is output from the speaker 50 to the external ear canal 2a. 2 is calculated as the difference level ΔA and the measurement data is calibrated based on the difference level ΔA, so that the following operational effects are obtained. be able to.

  That is, when the air leak from the external auditory canal 2a increases, the amplitude of the internal pressure change is attenuated more in the low frequency region, so that the difference level ΔA increases as the air leak from the external auditory canal 2a increases. Therefore, by calibrating the measurement data for air leakage from the ear canal 2a based on the difference level ΔA, it is possible to perform appropriate calibration without using a coupler for setting the reference level as in the prior art.

  In addition, by adopting the calibration method of the present embodiment, the following effects can be obtained.

  That is, in the conventional calibration method, when the measurement data is calibrated, the amplitude of the calibration sound detected in the coupler is set to the reference level. In such a calibration method, the dimension of the ear canal of the subject 2 is set. Even individual differences are not considered. Therefore, in the case of the subject 2 whose volume of the ear canal 2a is larger than the volume of the coupler, the amplitude of the calibration sound detected at this time is detected in the coupler even if the sensor unit 10 is sealed. It may become smaller than the amplitude of the calibration sound, and it may be determined that there is an air leak.

  In that respect, in the calibration method of the present embodiment, the measurement data can be calibrated with the sensor unit 10 attached to the ear canal 2a without using a coupler. It is possible to perform highly accurate measurement in consideration.

  In the calibration method of the present embodiment, a 10 Hz pure tone (that is, a pure tone in a non-audible frequency range lower than the audible frequency range) is used as the first pure tone, and a 30 Hz pure tone (that is, an audible frequency) is used as the second pure tone. Since the pure tone of the area is used, the following effects can be obtained.

  That is, in the case where a single pure tone is used as the calibration sound as in the prior art, if the frequency of the calibration sound is far away from the frequency of the biological sound, the influence of air leakage from the external auditory canal 2a on the measurement data is affected. It becomes difficult to evaluate accurately. On the other hand, when a pure sound in a non-audible frequency range lower than the audible frequency range is used as the calibration sound, the calibration sound cannot be heard by the subject 2 and it is difficult to perform the calibration work smoothly.

  On the other hand, by using a pure tone in the non-audible frequency range lower than the audible frequency range as the first pure tone, the frequency of the calibration sound can be brought close to the frequency of the biological sound, so that air leakage from the ear canal 2a is measured. It becomes easy to accurately evaluate the influence on the data, and thereby the calibration accuracy of the measurement data can be increased. Further, by using a pure tone in the audible frequency region as the second pure tone, the calibration sound can be heard by the subject 2, so that the calibration operation can be performed smoothly.

  At this time, in the calibration method of the present embodiment, the amplitude ratio between the first pure tone and the second pure tone is set to a value of 2 times or more, so the following operational effects can be obtained.

  That is, when a pure tone in a non-audible frequency range lower than the audible frequency range is used as the first pure tone, the amplitude of the biological sound existing near the frequency of the first pure tone is large. It is not easy to secure S / N when performing. On the other hand, when the amplitude of the second pure tone in the audible frequency region is increased, there is a possibility that the subject 2 may feel uncomfortable during the calibration work. Therefore, by setting the amplitude ratio between the first pure tone and the second pure tone to a value that is twice or more, the S / when the calibration operation is performed without causing the subject 2 to feel uncomfortable. N can be secured.

  In the calibration method of the present embodiment, the frequency spectrum S0 is detected with the sensor unit 10 mounted on the ear canal 2a in three modes having different degrees of air leakage, respectively, and the frequency spectrum is detected. From the amplitude attenuation in the frequency spectrums S1 and S2 detected in the presence of air leakage and the difference levels ΔA0, ΔA1 and ΔA2 in the frequency spectra S0, S1 and S2, respectively. A correction curve L1 indicating the correction amount of the amplitude of the sound is generated, and a waveform obtained by adding the correction amount for each frequency to the waveform of the biological sound based on the correction curve L1 is used as the measurement data of the biological sound. Therefore, the following effects can be obtained.

  That is, in the present embodiment, it is necessary to perform the same operation as the conventional preliminary operation, but by adopting such a calibration method, the measurement data of the body sound is calibrated so that the waveform approaches an appropriate shape. can do.

  In the present embodiment, since the correction curve L1 is approximated by a broken line, calibration for approximating the waveform of the measurement data of the body sound to an appropriate shape can be performed by a simple calculation process.

  In addition, in the present embodiment, the correction curve L1 is created in advance by measuring a body sound in an individual different from the subject 2, and thus places an extra burden on the subject 2 itself. Calibration can be performed without any problems.

  Instead of doing this, it is also possible to create the correction curve L1 by measuring the body sound in the subject 2 itself.

  In the above-described embodiment, a 10 Hz pure tone is used as the first pure tone, and a 30 Hz pure tone is used as the second pure tone. However, it is of course possible to use a pure tone having a frequency other than this.

  In the above embodiment, the amplitude ratio between the first pure tone and the second pure tone has been described as being set to a value that is twice or more. However, a configuration in which the amplitude ratio is set to a value that is less than twice is also possible. Is possible.

  In the above-described embodiment, the ear tip 16 of the sensor unit 10 has been described as configured so that the ear canal 2a is a sealed space when properly inserted into the ear canal 2a of the subject 2. Instead of a simple configuration, it is also possible to have a configuration having an air vent structure (air venting structure) for reducing the feeling of pressure when attached to the ear canal 2a. When such an ear tip is employed, the external auditory canal 2a does not become a sealed space, but the measurement of biological sound can be appropriately performed by employing the measurement data calibration method according to the present embodiment.

  Although the biological sound measurement system 100 according to the embodiment has been described as being configured to perform transmission and reception by wireless communication between the sensor unit 10 and the monitoring side unit 110, the sensor unit 10, the monitoring side unit 110, and It is also possible to adopt a configuration in which are connected by a cord or the like.

  In the above-described embodiment, the case where the pressure sensor 20 is an electret condenser microphone has been described. However, other microphones (for example, an electrodynamic microphone in which a vent hole is formed in the back space of the diaphragm) can be employed. is there.

  In the above-described embodiment, the case where the speaker 50 is a balanced armature type speaker has been described, but a speaker other than this (for example, an electrodynamic speaker) may be employed.

  In addition, the numerical value shown as a specification in the said embodiment is only an example, and of course, you may set these to a different value suitably.

  The present invention is not limited to the configurations and methods described in the above embodiment, and configurations and methods with various other modifications can be employed.

2 Subject 2a External auditory canal 10 Sensor unit 12 Housing 12a Sound guide hole 12A Front member 12Aa Front end wall 12Ab Small diameter cylindrical portion 12B Rear member 16 Ear tip 16a Through hole 16A, 16B Flange portion 18 Gasket 18a First through hole 18b Second Through hole 20 Pressure sensor 22 Diaphragm 24, 52 Housing 24a Sound collection hole 24b Vent hole 26 Sound collection nozzle 28 Cylindrical member 50 Speaker 52a Sound emission hole 54 Sound emission nozzle 60 Signal processing circuit unit 70 Battery 100 Living body sound measurement system 110 Monitoring Side unit 112 CPU
114 Memory 116 Display A1 Amplitude of change in internal pressure at frequency of first pure tone A2 Amplitude of change in internal pressure at frequency of second pure tone At1, At2 Attenuation spectrum At1a, At2a Approximate curve C Internal space C1 First space C2 Second space Cf Front space Cr Back space L1 Correction curve S0, S1, S2 Frequency spectrum ΔA, ΔA0, ΔA1, ΔA2 Difference level

Claims (6)

A living body configured to measure a body sound of the subject by detecting a change in internal pressure of the ear canal with the pressure sensor in a state where a sensor unit including a pressure sensor is attached to the ear canal of the subject. In the sound measurement system,
A monitoring-side unit that performs processing for measuring the body sound using the detection result of the internal pressure change;
The sensor unit includes a speaker capable of outputting an acoustic signal to the ear canal,
The monitoring side unit outputs a composite sound in which the first and second pure sounds having different frequencies are combined as calibration sound from the speaker to the ear canal, and uses the change in internal pressure of the ear canal due to the output of the calibration sound. A biological sound measurement system configured to calibrate the measurement data. The biological sound measurement system according to claim 1, wherein the measurement data of the biological sound is calibrated.
From the frequency spectrum of the internal pressure change of the external auditory canal detected by the pressure sensor when the calibration sound is output from the speaker to the external ear canal, the amplitude of the internal pressure change at the frequency of the first pure sound and the frequency of the second pure sound A method for calibrating measurement data, comprising: calculating a difference from an amplitude of an internal pressure change as a difference level and calibrating the measurement data based on the difference level. As the first pure tone, a pure tone in a non-audible frequency range lower than the audible frequency range is used,
The measurement data calibration method according to claim 2, wherein a pure tone in an audible frequency range is used as the second pure tone.   4. The measurement data calibration method according to claim 3, wherein an amplitude ratio between the first pure tone and the second pure tone is set to a value of twice or more.   The sensor unit is attached to the ear canal in a plurality of modes with different degrees of air leakage, and the frequency spectrum is detected, respectively, and there is air leakage with respect to the frequency spectrum detected with almost no air leakage. A correction curve indicating the correction amount of the amplitude of the biological sound according to the frequency is created from the detected amplitude attenuation amount in the frequency spectrum and the difference level in each frequency spectrum, and based on the correction curve, the correction curve is generated. 5. The measurement data calibration method according to claim 2, wherein a waveform obtained by adding the correction amount for each frequency to the waveform of the body sound is used as the measurement data of the body sound.   6. The measurement data calibration method according to claim 5, wherein the correction curve is approximated by a broken line.

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