JP6676258B2 - Calibration method of measurement data in body sound measurement system - Google Patents

Description

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

  2. Description of the Related Art Conventionally, medical devices and health management devices that include a body sound measurement system for measuring a body sound of a subject have been known.

  Further, as such a body sound measurement system, a sensor unit having a pressure sensor is attached to the external auditory canal of a subject, and the pressure sensor detects a change in the internal pressure of the external auditory canal, thereby detecting the body sound of the subject. Are known that are configured to measure

  Patent Literature 1 discloses such a body sound measurement system in which an ear tip constituting a part of a sensor unit is inserted into an external auditory canal of a subject, and a jugular vein pressure is measured as the body sound. What was done is described.

  Patent Document 2 discloses a sensor unit used in a body sound measurement system that includes a speaker that can output an acoustic signal to an external auditory meatus as well as a pressure sensor.

Japanese Patent No. 558595 JP 2012-508605 A

  In such a body sound measurement system, if the sensor unit is not properly attached to the subject's external auditory meatus, air leaks will occur, so it is not possible to accurately detect changes in the internal pressure of the external auditory meatus, For this reason, the measurement of the body sound cannot be performed properly.

  Therefore, in order to properly measure the body sound, it is ideal that the ear canal be a completely enclosed space when the sensor unit is attached to the ear canal.

  However, in practice, when the sensor unit is attached to the ear canal, some air leakage inevitably occurs. Therefore, it is desired to perform some calibration on the measurement data of the body sound.

  The present invention has been made in view of such circumstances, and has as its object to provide a method capable of calibrating measurement data of a body sound in a body sound measurement system.

  The invention of the present application is intended to achieve the above object by using a speaker as a sensor unit and using the speaker for calibration of measurement data.

That is, the calibration method of the measurement data in the body sound measurement system according to the present invention,
A body configured to measure the body sound of the subject by detecting a change in the internal pressure of the ear canal by the pressure sensor while the sensor unit having the pressure sensor is attached to the ear canal of the subject. In the sound measurement system, a method of calibrating the measurement data of the body sound,
On the sensor unit, a speaker having a configuration capable of outputting an acoustic signal to the ear canal is provided.
When detecting a change in the internal pressure of the external auditory canal by the pressure sensor, a pure sound is output from the speaker to the external auditory canal as a calibration sound, and the measurement data is calibrated using the internal pressure change of the external auditory canal due to the output of the calibration sound. It is characterized by the following.

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

  The specific frequency and amplitude of the “calibration sound” are not particularly limited as long as they are pure sounds.

  A specific method for “calibrating the measurement data using a change in the internal pressure of the ear canal due to the output of the calibration sound” is not particularly limited.

  In the body sound measurement system according to the present invention, in a state where the sensor unit is mounted on the external auditory canal of the subject, the internal pressure of the external auditory canal is detected by the pressure sensor, so that the body sound of the subject is measured. However, when the sensor unit is equipped with a speaker capable of outputting an acoustic signal to the ear canal, when a pressure sensor detects a change in the internal pressure of the ear canal, a pure sound is output from the speaker to the ear canal as a calibration sound. Since the measurement data is calibrated using the change in the internal pressure of the external auditory canal due to the output of the calibration sound, the following operation and effect can be obtained.

  That is, even when some air leakage occurs when the sensor unit is attached to the ear canal, the body sound can be properly measured by calibrating the measurement data by outputting the calibration sound from the speaker.

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

  Thus, even when the sensor unit is slightly incompletely attached to the ear canal, it is possible to appropriately measure the body sound. Therefore, in order to reduce the feeling of pressure when the sensor unit is attached to the external auditory canal, even if the air vent structure is adopted for the sensor unit, the measurement of the body sound can be appropriately performed. In addition, since the influence of the variation in the mounting state of the sensor unit can be removed from the measurement data of the body sound, the accuracy of the measurement data of the body sound can be improved.

  In the present invention, the following method can be adopted as a specific method for calibrating the measurement data of the body sound.

That is, a coupler having a simulated space having substantially the same volume as the ear canal in a state where the sensor unit is mounted is prepared, and the sensor unit is mounted on the coupler so that the simulated space is completely enclosed. After setting the amplitude of the calibration sound detected by the pressure sensor when the calibration sound is output as the reference level, the sensor unit is deliberately attached to the ear canal in such a manner as to cause air leakage, and the pressure sensor detects the amplitude of the ear canal. The preparatory operation for preliminarily detecting the change in the internal pressure includes 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. Is repeated several times, and the amplitude of the calibration sound is obtained from the calibration sound and the body sound detected by these multiple preliminary operations. We derived an approximate expression indicating the relationship between the amplitude of the body sound, after calculating the reference level of the amplitude of the body sound corresponding from the approximate expression in the reference level of the amplitude of the calibration tone, from the reference level of the amplitude of the calibration tone It is possible to adopt a method of creating a characteristic curve indicating the relationship between the amount of attenuation and the amount of attenuation of body sound amplitude from a reference level, and calibrating the measurement data based on this characteristic curve.

  By employing such a calibration method, it is possible to accurately calibrate the measurement data by outputting the calibration sound from the speaker.

  At this time, the following method can be adopted as a specific method for calibrating the measurement data based on the characteristic curve.

That is, the main operation of actually detecting the change in the internal pressure of the external auditory canal by the pressure sensor with the sensor unit attached to the external auditory canal of the subject is performed so that the first and second time regions are included. based on the detected calibration sound and body sound, the attenuation amount from the reference level of the amplitude of the body sound corresponding to the attenuation amount from the reference level of the amplitude of the calibration tone is calculated from the characteristic curve was the calculated It is possible to adopt a method in which the amplitude of the attenuation amount is added to the amplitude of the body sound detected by the pressure sensor to obtain measurement data of the body sound.

  By adopting such a calibration method, it is possible to calibrate the measurement data of the body sound so that the amplitude becomes an appropriate value.

  Further, as a specific method for calibrating the measurement data based on the characteristic curve, the following method can be employed.

That is, the main operation of actually detecting a change in the internal pressure of the external auditory canal by the pressure sensor with the sensor unit attached to the external auditory canal is performed so as to include the first and second time regions, and the calibration detected by this main operation is performed. based on the sound and body sound, the attenuation amount from the reference level of the amplitude of the body sound corresponding to the attenuation amount from the reference level of the amplitude of the calibration tone is calculated from the characteristic curve, the calculated attenuation amount Assuming that the amplitude is the attenuation of the amplitude of the pure sound at the frequency calculated as the reciprocal of the period of the body sound, the attenuation of the amplitude of the pure sound, the frequency of the pure sound and the attenuation of the amplitude of the calibration sound and the calibration From the sound frequency, a correction curve indicating the correction amount of the amplitude of the body sound according to the frequency is created, and a waveform obtained by adding the correction amount for each frequency to the waveform of the body sound based on the correction curve How to measure data of the body sound can be adopted.

  By employing such a calibration method, it is possible to calibrate the measurement data of the body sound so that its waveform approaches an appropriate shape.

  Further, in the present invention, the following method can be employed as a specific method for calibrating the measurement data of the body sound.

  That is, a coupler having a simulation space having substantially the same volume as the ear canal in a state where the sensor unit is mounted is prepared, and the sensor unit is mounted on the coupler so that the simulation space is completely enclosed. The amplitude of each calibration sound detected by the pressure sensor when a plurality of pure tones with different frequencies are output as calibration sounds is set as the reference level of each calibration sound, and then the pressure is measured with the sensor unit attached to the ear canal. This operation of actually detecting the change in the internal pressure of the ear canal by the sensor is performed so that the first time region in which each calibration sound is output from the speaker and the second time region in which each calibration sound is not output from the speaker are included. Based on each calibration sound detected by this operation, the amount of attenuation of the amplitude of each calibration sound from each reference level is calculated, and A correction curve indicating the correction amount of the amplitude of the body sound according to the frequency is created from the attenuation amount of the amplitude of the true sound, and the correction amount is added to the waveform of the body sound for each frequency based on the correction curve. Can be adopted as the measurement data of the body sound.

  By adopting such a calibration method, it is possible to calibrate the measurement data of the body sound so that its waveform is closer to an appropriate shape.

FIG. 1 is a schematic diagram showing a body sound measurement system used in a method for calibrating measurement data in a body sound measurement system according to an embodiment of the present invention. Side sectional view showing a sensor unit of the above body sound measurement system Sectional side view showing in detail the configuration of the pressure sensor in the sensor unit. The figure which shows the relationship between the mounting conditions of a sensor unit, and the measurement data of a pulse sound when measuring the pulse sound of a test subject by the said body sound measurement system. The figure which shows the example of sound collection at the time of the preliminary operation in the <1st calibration method> which concerns on the said embodiment. The figure which shows the waveform of the calibration sound and the pulse sound collected in the said sound collection example. Graph showing the relationship between the amplitude of the calibration sound and the amplitude of the pulse sound collected by the above preliminary operation FIG. 9 is a diagram showing a characteristic curve indicating a relationship between the attenuation amount of the calibration sound and the attenuation amount of the pulse sound. The figure which shows the measurement data calibrated by said <1st calibration method> with the measurement data before a calibration, and the measurement data when there is almost no air leak. The figure which shows the frequency correction straight line created in the <2nd calibration method> which concerns on the said embodiment. The figure which shows the measurement data calibrated by said <2nd calibration method> with the measurement data before a calibration, and the measurement data when there is almost no air leak. The figure which shows the frequency correction curve created in <third calibration method> which concerns on the said embodiment. The figure which shows the correction curve created in <4th calibration method> which concerns on the said embodiment. The figure which shows the measurement data calibrated by said <4th calibration method> with the measurement data before a calibration, and the measurement data when there is almost no air leak.

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

  FIG. 1 is a schematic diagram showing a body sound measurement system 100 used for a method for calibrating measurement data in a body sound measurement system according to one embodiment of the present invention.

  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 and reception by wireless communication between the two.

  In the body sound measurement system 100, the pulse sound of the subject 2 is converted into a body sound by detecting a change in the internal pressure of the ear canal 2a while the sensor unit 10 is attached to the external ear canal 2a of the subject 2. It is designed to measure.

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

  Before describing a method of calibrating measurement data of pulse sounds in the body sound measurement system 100 according to the present embodiment, the configuration of the sensor unit 10 will be described.

  FIG. 2 is a side sectional view showing the sensor unit 10.

  As shown in FIG. 1, the sensor unit 10 includes a housing 12 having a sound guide hole 12a formed at a front end (right end in FIG. 2), a pressure sensor 14 and a speaker 20 housed in the housing 12. And an ear tip 16 attached to the front end of the housing 12.

  In the sensor unit 10, a pulse sound generated as a change in the internal pressure of the ear canal 2 a is collected by the pressure sensor 14 with the ear tip 16 inserted into the ear canal 2 a of the subject 2.

  The housing 12 has a configuration in which a front member 12A and a rear member 12B are joined. Both the front member 12A and the rear member 12B are made of a hard material such as aluminum or hard resin.

  The front member 12A is formed so that its diameter decreases toward the front, and a small-diameter cylindrical portion 12Ab that projects forward is formed at the center of the front end wall 12Aa. The sound guide hole 12a is formed in the small-diameter cylindrical portion 12Ab, and the ear tip 16 is mounted on the small-diameter cylindrical portion 12Ab.

  The rear end face 12Ac of the front member 12A is formed in an annular shape. The inner peripheral surface 12Ad of the front member 12A is formed of a cylindrical surface whose diameter increases in two stages toward the rear.

  The rear member 12B is configured as a cylindrical member with a bottom extending in the front-rear direction, and the rear end is configured as a rear end wall 12Bb. The front end surface 12Ba of the rear member 12B is sealed over the entire periphery by welding, bonding, or the like in a state in which the front end surface 12Ba is in contact with the outer peripheral edge of the rear end surface 12Ac of the front member 12A.

  Thus, the internal space C of the housing 12 is configured as a closed space except for the sound guide hole 12a.

  At the front end of the internal space C of the housing 12, a gasket 18 having a cylindrical outer peripheral surface is arranged. This gasket 18 is made of a soft material such as silicone resin or rubber. The gasket 18 has its outer peripheral surface fitted into the small diameter portion of the inner peripheral surface 12Ad of the front member 12A from the rear side, and its front end surface contacts the front end wall 12Aa of the front member 12A. Has been inserted.

  The gasket 18 has a first half formed in a cylindrical shape and a second half formed in a cylindrical shape, and a first and second through-holes 18a extending in the front-rear direction with a circular cross-sectional shape are formed in the center of the latter 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 14 is disposed behind the speaker 20. Further, a signal processing circuit unit 60 is arranged at a position on the rear side of the speaker 20 in the internal space C along with the pressure sensor 14, and a battery 70 is further arranged on the rear side. The signal processing circuit unit 60 and the battery 70 are supported by the rear member 12B.

  The signal processing circuit unit 60 has an antenna function, and is configured to be able to transmit and receive to and from the monitoring unit 110 (see FIG. 1). The battery 70 is configured to supply power to the pressure sensor 14, the speaker 20, and the signal processing circuit unit 60.

  The speaker 20 is a balanced armature type speaker, and has a configuration in which a diaphragm and a drive unit (not shown) are housed in a housing 52.

  The housing 52 has a substantially rectangular parallelepiped outer shape that is long in the front-rear direction, and has a sound emission hole 52a formed at the lower end of the front end surface. At the front end of the housing 52, a sound emitting nozzle 54 formed so as to surround the sound emitting hole 52a is attached by welding or the like. A pair of terminal portions 20a for electrically connecting the speaker 20 to the signal processing circuit unit 60 are disposed at the rear of the housing 52.

  The speaker 20 is positioned with the distal end of the sound emission nozzle 54 inserted into the second through hole 18b of the gasket 18 from the rear side. The speaker 20 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 via the sound emission hole 52a and the second through hole 18b. Has become.

  In the internal space C of the housing 12, a tubular member 28 extending in the front-rear direction is disposed below the speaker 20. The tubular member 28 may be made of a hard material such as aluminum or hard resin, or may be made of a soft material such as silicone resin or rubber. The front end of the tubular member 28 is inserted into the first through hole 18a of the gasket 18. The tubular member 28 is formed to extend to the rear of the speaker 20.

  The pressure sensor 14 is a small 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 has a sound collection hole 24a and a ventilation hole 24b that allow each of 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 14 is disposed along a vertical plane perpendicular to the front-rear direction, and is connected to a rear end of the tubular member 28 at a sound collection nozzle 26. This connection is performed by inserting the front end of the sound pickup nozzle 26 into the rear end of the tubular member 28.

  Thus, 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.

  As for the positioning of the pressure sensor 14 and the cylindrical member 28, the front end of the sound collecting nozzle 26 is inserted into the rear end of the cylindrical member 28 and the front end of the cylindrical member 28 is inserted into the first through hole of the gasket 18. It may be performed only by inserting into the housing 18a, or a structure in which a spacer (not shown) is arranged between the housing 24 and the inner peripheral surface of the rear member 12B and supported at a plurality of locations in the circumferential direction. It may be performed additionally.

  Further, the positioning of the speaker 20 may be performed only by inserting the distal end portion of the sound emission nozzle 54 into the second through hole 18b of the gasket 18, or the housing 52 and the inner peripheral surface of the rear member 12B. Alternatively, a structure (not shown) may be provided between them to support at a plurality of positions in the circumferential direction.

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

  A through hole 16a is formed in the center of the ear tip 16 so as to penetrate the ear tip 16 in the front-rear direction. The through hole 16a communicates with the sound guide hole 12a when the ear tip 16 is mounted on the small-diameter cylindrical portion 12Ab. The through hole 16a is formed with a smaller diameter than the sound guide hole 12a.

  The ear tip 16 is provided with two front and rear flange portions 16A and 16B which spread in a substantially parabolic shape toward the rear side. At this time, the rear flange portion 16B is formed with a larger diameter than the front flange portion 16A. 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. To form a space.

  Vibrations of the ear canal wall and the eardrum due to the pulse of the subject 2 are radiated into the closed ear canal 2a. At this time, a pulse sound generated as a change in the internal pressure of the ear canal 2a is collected by the pressure sensor 14. It will be.

  FIG. 3 is a side sectional view showing the configuration of the pressure sensor 14 in detail.

  As shown in the figure, the pressure sensor 14 is an electret condenser microphone having a circular outer shape of about φ5 to 10 mm and a thickness of about 1 to 3 mm in a front view.

  The pressure sensor 14 has a configuration in which the diaphragm 22 is housed in the housing 24 together with the support ring 32, the back electrode plate 34, the spacer 36, the conductive member 38, the insulating member 40, and the impedance conversion element 42.

  The housing 24 includes a conductive cover 44 and a circuit board 46.

  The conductive cover 44 is a cap-shaped member having a circular external shape in a front view, and is formed by pressing a metal plate. On the other hand, the circuit board 46 has a circular shape with an outer diameter slightly smaller than the inner diameter of the conductive cover 44 when viewed from the front, and is arranged parallel to the front wall of the conductive cover 44. At the rear end portion of the peripheral surface wall of the conductive cover 44, an annular bent portion 44a extending so as to be bent inward is extended, and the annular bent portion 44a is caulked and fixed to the circuit board 46 at the annular bent portion 44a. I have.

  The sound collection hole 24 a of the housing 24 is formed at the center of the front wall of the conductive cover 44. The ventilation hole 24b of the housing 24 is formed in the circuit board 46. Each of the sound collection hole 24a and the ventilation hole 24b has a circular shape, and the diameter of the ventilation hole 24b is smaller than that of the sound collection hole 24a. Note that each of the sound collection hole 24a and the ventilation hole 24b may be formed of a plurality of small holes.

  A circular opening 26 a is formed at the tip of the sound pickup nozzle 26.

  The diaphragm 22 has a configuration in which a metal vapor-deposited film is formed on the front surface of a polymer film, and a fine hole 22a for adjusting the atmospheric pressure is formed at the center thereof. The diaphragm 22 is supported by a support ring 32 at an outer peripheral edge thereof. The support ring 32 is formed of a thin metal plate, and is formed in an annular shape. The diaphragm 22 is stretched and fixed to the rear surface of the support ring 32 (that is, fixed by bonding or the like with tension applied).

  The rear electrode plate 34 has a circular outer shape slightly smaller than the outer peripheral surface of the support ring 32 when viewed from the front, and is arranged close to the rear of the diaphragm 22. The rear electrode plate 34 has a configuration in which an electret layer 34a is disposed on the front surface of an electrode plate main body made of a metal plate. The electret layer 34a is generated by subjecting an insulating film formed on the front surface of the electrode plate main body to a polarization treatment at a predetermined charge voltage, thereby applying a predetermined surface potential. The back electrode plate 34 is formed with through holes 34b penetrating the back electrode plate 34 in the front-rear direction at a plurality of positions in the circumferential direction.

  The spacer 36 is formed of an annular resin thin plate, and is disposed between the diaphragm 22 and the back electrode plate 34. The capacitor portion is formed by arranging the diaphragm 22 and the electret layer 34a of the back electrode plate 34 in parallel and opposed via the spacer 36.

  The circuit board 46 is arranged behind the back electrode plate 34. On both front and rear surfaces of the circuit board 46, conductive layers (not shown) are formed in a predetermined pattern. A pair of terminal portions 14 a for electrically connecting the pressure sensor 14 to the signal processing circuit 60 are formed on the rear surface of the circuit board 46.

  The impedance conversion element 42 is mounted on the front surface of the circuit board 46. At this time, the impedance conversion element 42 is arranged at a position deviated from the formation position of the ventilation hole 24b.

  The conducting member 38 is a substantially cylindrical member, and is arranged between the circuit board 46 and the back electrode plate 34 so as to establish conduction between them.

  The insulating member 40 is an annular member, and is arranged between the back electrode plate 34 and the conductive member 38 and the peripheral wall of the conductive cover 44 so as to insulate them from each other.

  As described above, the conductive cover 44 is fixed by caulking to the circuit board 46 at the annular bent portion 44a, and the conductive cover 44 and the conductive layer formed on the rear surface of the circuit board 46 are fixed by the caulking. And electrical continuity.

  Next, a method of calibrating measurement data of a pulse sound in the body sound measurement system 100 according to the present embodiment will be described.

  As described above, in the present embodiment, with the ear tip 16 of the sensor unit 10 inserted into the external auditory canal 2a of the subject 2, the pulse sound of the subject 2 generated as a change in the internal pressure of the external auditory canal 2a is collected. At this time, if the ear tip 16 is not properly inserted into the external auditory canal 2a, the closed space is not formed, so that the pulse sound cannot be properly collected.

  FIG. 4 is a diagram illustrating a relationship between the mounting condition of the sensor unit 10 and the measured data of the pulse sound when the pulse sound of the subject 2 is collected.

  FIG. 4A shows measurement data of a pulse sound collected in a state where the sensor unit 10 is substantially properly mounted on the external auditory canal 2a and there is almost no air leakage.

  The measurement data of the pulse sound includes the biological information of the subject 2 in the amplitude, peak interval, and shape of the periodic waveform.

  FIGS. 4B and 4C are measurement data of pulse sounds collected in a state where the sensor unit 10 is not properly attached to the external auditory meatus 2a. In this case, FIG. 4B shows measurement data when air leakage is relatively small, and FIG. 4C shows measurement data when air leakage is relatively large.

  In each of the graphs showing the measurement data of the pulse sound, the horizontal axis represents time (second), and the vertical axis represents amplitude.

  As shown in FIGS. 4B and 4C, when the sensor unit 10 is not properly attached to the external auditory canal 2a, air leakage occurs, and thus the measurement data of the pulse sound is shown in FIG. The amplitude becomes smaller than the measured data, and the waveform shape changes. Therefore, it is difficult to correctly evaluate the biological information of the subject 2.

  On the other hand, when the subject 2 inserts the ear tip 16 into the ear canal 2a, it is not always easy to properly perform the insertion.

  Therefore, in the present embodiment, the following calibration is performed on the pulse sound measurement data, so that even if the ear tip 16 is not properly inserted, the pulse sound measurement data can be appropriately adjusted. Value.

  That is, in the present embodiment, when the pressure sensor 14 detects a change in the internal pressure of the external auditory canal 2a, a pure sound is output as a calibration sound from the speaker 20 to the external auditory canal 2a, and the internal pressure change of the external auditory canal 2a due to the output of the calibration sound is utilized. Calibration of measurement data is performed.

  Hereinafter, a specific method of calibrating the measurement data of the pulse sound in the body sound measurement system 100 according to the present embodiment will be described.

  First, the <first calibration method> according to the present embodiment will be described.

  In the <first calibration method>, the amplitude of the measured pulse sound data is calibrated.

  That is, first, as shown in FIG. 1, a coupler 4 having a simulation space 4a having substantially the same volume (specifically, a volume of about 1 cc) as the ear canal 2a in a state where the sensor unit 10 is mounted is prepared. The simulated space 4a is completely enclosed by mounting the sensor unit 10 on the coupler 4. At this time, the sensor unit 10 may be mounted by inserting the ear chip 16 into the coupler 4, or the sensor unit 10 may be mounted using a dedicated adapter (not shown) instead of the ear chip 16. May be performed. In any case, the simulated space 4a of the coupler 4 is set to have substantially the same volume as the external auditory canal 2a when the sensor unit 10 is mounted.

  Then, a pure sound of 30 Hz is output as a calibration sound from the speaker 20 to the simulation space 4a and collected by the pressure sensor 14, and the amplitude of the calibration sound collected at this time is set as a reference level Ac0.

  At this time, the pure tone as the calibration tone is preferably set to a frequency as low as possible, but a pure tone of about 30 Hz is appropriate in consideration of the audible frequency range, the performance of the speaker 20, and the like. Note that it is also possible to output a pure tone having a frequency other than 30 Hz as the calibration tone. Further, it is preferable to set the amplitude of the calibration sound to a value larger than the maximum amplitude of the pulse sound in order to increase the accuracy of the calibration.

  Next, in a state where the sensor unit 10 is attached to the external auditory canal 2a of the subject 2 (that is, a state in which the ear tip 16 is inserted into the external auditory canal 2a), the pressure sensor 14 preliminary detects a change in the internal pressure of the external auditory canal 2a. Operation ".

  This preliminary operation includes a first time region in which the same calibration sound is output as the calibration sound output from the speaker 20 to the simulation space 4a of the coupler 4, and a second time region in which the calibration sound is not output from the speaker 20. Do so as to be included.

  FIG. 5 is a diagram illustrating an example of sound collection when about 15 seconds are set as the first time area and about 15 seconds are subsequently set as the second time area.

  As shown in the figure, in the first time domain, the calibration sound has a waveform in which the pulse sound indicating the change in the internal pressure of the external auditory meatus 2a is superimposed. In the second time domain in which the output of the calibration sound is stopped, , The waveform is only a pulse sound.

  Thereafter, once the sensor unit 10 is detached from the external auditory canal 2a, the sensor unit 10 is attached to the external auditory canal 2a again to perform the above-described preliminary operation, and this operation is repeated several times. At this time, by appropriately changing the manner of inserting the ear tip 16 into the external auditory canal 2a, air leakage is intentionally generated under various mounting conditions.

  Next, based on the calibration sound and the pulse sound detected by the plurality of preliminary operations, the relationship between the attenuation amount of the amplitude Ac of the calibration sound from the reference level Ac0 and the corresponding attenuation amount of the amplitude Ap of the pulse sound. Is created.

  Specifically, first, as shown in FIG. 6A, only the waveform of the calibration sound is extracted from the waveform in the first time domain by high-pass filtering, and the amplitude is read from the measurement data of the calibration sound. The average value of the maximum amplitude values (peak-peak values) for 10 waves is obtained, and this is set as the amplitude Ac of the calibration sound. Further, as shown in FIG. 6B, the amplitude is read from the pulse sound measurement data in the second time domain, and the average value of the maximum amplitude values for 10 waves is obtained. I do.

  Next, as shown in FIG. 7, the relationship between the amplitude Ac of the calibration sound and the amplitude Ap of the pulse sound collected by the plurality of preliminary operations is graphed to derive an approximate expression.

When the amplitude Ac is x and the amplitude Ap is y, for example, as shown in FIG.
Y = 1.0022x−6098.7
Is represented by

  Then, the reference level Ap0 of the pulse sound amplitude Ap corresponding to the reference level Ac0 (that is, the amplitude Ap of the pulse sound collected in an ideal state with no air leakage) is estimated from the approximate expression. Specifically, the reference level Ac0 is substituted for x in the above approximate expression, and the reference level Ap0 is calculated as y.

  Next, the amplitude Ac of the calibration sound is standardized (logarithmic display) with a reference level Ac0, and the reference level Ac0 is set to 0 dB. Further, the amplitude Ap of the pulse sound is standardized by the reference level Ap0, and the reference level Ap0 is set to 0 dB.

  Then, the attenuation Dc of the amplitude Ac of the calibration sound collected by the plurality of preliminary operations from the reference level Ac0 and the attenuation Dp of the amplitude Ap of the pulse sound from the reference level Ap0 are calculated.

These attenuation amounts Dc and Dp are:
Dc = −20 Log ₁₀ (Ac / Ac0) [dB]
Dp = −20 Log ₁₀ (Ap / Ap0) [dB]
Is represented by

  Next, as shown in FIG. 8, a characteristic curve L1 showing the relationship between the calibration sound attenuation Dc and the pulse sound attenuation Dp is created.

When the attenuation amount Dc is x and the attenuation amount Dp is y, for example, as shown in FIG.
Y = 0.0418x ² + 1.6163x
Is represented by

  In addition, considering the individual difference of the subject 2, it is preferable that the plurality of preliminary operations be performed by attaching the sensor unit 10 to the external auditory canal 2a of the two subjects. It is also possible to prepare the characteristic curve L1 in advance by performing the preliminary operation a plurality of times as described above with the subject 2 as the subject 2.

  Next, in a state where the sensor unit 10 is attached to the external auditory meatus 2a of the subject 2, the "main operation" of actually detecting a change in the internal pressure of the external auditory meatus 2a by the pressure sensor 14 is performed.

  Also in this operation, the first time region in which the same calibration sound as the calibration sound output from the speaker 20 to the simulation space 4a of the coupler 4 is output, and the second time region in which the calibration sound is not output from the speaker 20 Do so as to be included.

  Next, the amplitudes Ac and Ap are read from the calibration sound and the pulse sound collected by this operation. Then, the attenuation amount of the pulse sound amplitude Ap from the reference level Ap0 corresponding to the attenuation amount of the calibration sound amplitude Ac from the reference level Ac0 is calculated from the characteristic curve L1.

  Finally, a value corresponding to the calculated attenuation amount of the amplitude Ap is added as an amplitude correction amount to the amplitude Ap of the pulse sound detected by the pressure sensor 14 to obtain calibrated pulse sound measurement data.

  FIG. 9 is a diagram showing the measurement data thus calibrated together with the measurement data before calibration and the measurement data when there is almost no air leakage.

  The measurement data shown in FIG. 9 is measurement data of a pulse sound measured five times every hour in the daytime period of the day (9 to 13 o'clock). In this case, the graph indicated by the broken line is the measurement data before calibration, the graph indicated by the solid line with a black solid square is the measurement data after the calibration, and the measurement data indicated by the solid line with a triangle is almost air leakage. This is the measurement data when there is no data.

  As is clear from FIG. 9, the amplitude of the measured data after calibration has increased to a value close to the measured data when there is almost no air leakage, compared to the measured data before calibration.

  Next, the <second calibration method> according to the present embodiment will be described.

  In the <second calibration method>, the waveform of the measurement data of the pulse sound is calibrated.

  That is, first, the reference level Ac0 of the amplitude Ac of the calibration sound is set in the same manner as in the <first calibration method>. Then, the same preliminary operation as in the <first calibration method> is performed a plurality of times to create the characteristic curve L1 (see FIG. 8). Further, the same operation as in the <first calibration method> is performed, and based on the calibration sound and the pulse sound collected by this operation, the amplitude Ac of the calibration sound corresponds to the attenuation amount from the reference level Ac0. The amount of attenuation of the amplitude Ap of the pulse sound from the reference level Ap0 is calculated from the characteristic curve L1.

  Next, a correction curve indicating a correction amount of the amplitude Ap of the pulse sound according to the frequency is created from the calculated attenuation amount. Specifically, on the assumption that the value of the calculated attenuation amount of the amplitude Ap is the attenuation amount of the amplitude of the pure tone at a frequency (about 1 Hz) calculated as the reciprocal of the period of the pulse sound, the amplitude of the pure tone is determined. A frequency correction straight line L2 as shown in FIG. 10 is created from the attenuation amount of the pure sound and the attenuation amount of the amplitude Ac of the calibration sound and the frequency of the calibration sound (30 Hz).

The slope of the frequency correction straight line L2 is
Slope = (attenuation of amplitude Ac of calibration sound−attenuation of amplitude Ap of pulse sound) / (30−reciprocal of period of pulse sound)
Is represented by

Next, based on the frequency correction straight line L2, a correction amount at the frequency f (= attenuation amount at the frequency f) is calculated from the following equation.
Correction amount = attenuation amount of pulse sound amplitude Ap−inclination of frequency correction line L2 × (f−reciprocal of pulse sound period)
Finally, the correction amount is added to the pulse sound waveform for each frequency, and the waveform to which the correction amount is added is used as pulse sound measurement data.

  Specifically, the monitoring-side unit 110 performs a filtering process such that the correction amount is added for each frequency by performing a digital filtering process on the digital electric signal received from the sensor unit 10.

  FIG. 11 is a diagram showing the measurement data calibrated in this way together with the measurement data before calibration and the measurement data when there is almost no air leakage.

  The measurement data shown in FIG. 11A is the measurement data before calibration, the measurement data shown in FIG. 11B is the measurement data after calibration, and the measurement data shown in FIG. This is measured data when there is almost no leakage. In the graphs showing these measurement data, the horizontal axis represents time (second), and the vertical axis represents amplitude.

  As shown in FIG. 11, the measured data after the calibration has an amplitude that has increased to a value close to the measured data when there is almost no air leakage, compared to the measured data before the calibration, and a broken line in the figure. In the portion surrounded by the circle, the shape change of the waveform due to the calibration is remarkable. Thereby, the waveform of the measured data after calibration approaches the characteristic of the waveform of the measured data when there is no air leakage.

  Next, the <third calibration method> according to the present embodiment will be described.

  The <third calibration method> is basically the same as the <second calibration method>, except that a correction curve indicating the correction amount of the pulse sound amplitude Ap according to the frequency is shown in FIG. A simple frequency correction curve L3 is created.

  This frequency correction curve L3 is created by logarithmic approximation from the result of this operation.

When the frequency is x and the correction amount is y, for example, as shown in FIG.
· Y = - 1.942 Ln (x ) +13.804
Is represented by

  Next, similarly to the <second calibration method>, the correction amount is added to the pulse sound waveform for each frequency, and the waveform to which the correction amount is added is used as pulse sound measurement data.

  In the <third calibration method>, the frequency correction curve L3 created by logarithmic approximation is used as the correction curve. 2 calibration method>.

  Next, a <fourth calibration method> according to the present embodiment will be described.

  In the <fourth calibration method>, as in the <third calibration method>, the amplitude and waveform of the pulse sound measurement data are calibrated, but four types of pure tones having different frequencies are used as the calibration sounds. As a result, the calibration is performed more finely.

  That is, first, similarly to the <first calibration method>, the reference level Ac0 of the amplitude of each of the four types of calibration sounds is set.

  At this time, similarly to the <first calibration method>, with the sensor unit 10 mounted on the coupler 4 and the simulation space 4a being a completely enclosed space, four types of calibration sounds are output from the speaker 20 to the simulation space 4a. Pure sounds of 10 Hz, 20 Hz, 30 Hz, and 50 Hz are output and collected by the pressure sensor 14. Then, the amplitudes of the four types of calibration sounds collected at this time are set as reference levels Ac0. Note that it is also possible to add a pure tone having a frequency other than 10 Hz, 20 Hz, 30 Hz, and 50 Hz as the calibration sound, or to change the frequency of a part thereof.

  Next, in a state where the sensor unit 10 is attached to the external auditory meatus 2a of the subject 2, this operation for actually detecting the change in the internal pressure of the external auditory meatus 2a by the pressure sensor 14 is performed four times in correspondence with four types of calibration sounds. .

  That is, first, a first time region in which the same calibration sound as the 10 Hz calibration sound output from the speaker 20 to the simulation space 4a is output, and a second time region in which no calibration sound is output from the speaker 20 are included. The first operation is performed in such a manner as to be performed.

  In the same manner, in the first time domain, calibration sounds of 20 Hz, 30 Hz, and 50 Hz are sequentially output, and the second to fourth main operations are performed. In the second to fourth main operations, the second time domain May be omitted. Further, the second time region may not be included in the first main operation but may be included in any one of the second to fourth main operations.

  Next, an attenuation amount Dc of the amplitude Ac of the calibration sound from the reference level Ac0 is calculated each time based on the calibration sound detected in each of these four operations.

This attenuation Dc is
Dc = −20 Log ₁₀ (Ac / Ac0) [dB]
Is represented by

  Next, a correction curve indicating the correction amount of the pulse sound amplitude Ap corresponding to the frequency is created from the attenuation amount of the calibration sound amplitude Ac calculated each time.

  FIG. 13 shows the correction curve L4 created in this manner.

When the frequency is x and the correction amount is y, for example, as shown in FIG.
Y = −3.666 Ln (x) +18.084
Is represented by

  Finally, based on the correction curve L4, a filtering process of adding the above-described correction amount to the pulse sound waveform for each frequency is performed, and the waveform to which the correction amount is added is used as pulse sound measurement data.

  FIG. 14 is a diagram showing the measurement data calibrated in this way, together with the measurement data before calibration and the measurement data when there is almost no air leakage.

  The measurement data shown in FIG. 14A is the measurement data before calibration, the measurement data shown in FIG. 14B is the measurement data after calibration, and the measurement data shown in FIG. This is measured data when there is almost no leakage. In the graphs showing these measurement data, the horizontal axis represents time, and the vertical axis represents amplitude. At this time, the amplitude of the measured data shown in FIG. 14A is considerably enlarged with respect to the actually measured waveform to facilitate comparison with the measured data shown in FIGS. 14B and 14C. Is shown.

  As shown in FIG. 14, the measured data after the calibration is closer to the characteristic of the waveform of the measured data when there is almost no air leakage as compared with the measured data before the calibration.

  Next, the operation and effect of the present embodiment will be described.

  In the body sound measurement system 100 according to the present embodiment, the sensor unit 10 is attached to the external auditory canal 2a of the subject 2, and the pressure sensor 14 detects a change in the internal pressure of the external auditory canal 2a, so that the subject 2 The sensor unit 10 is configured to include a speaker 20 capable of outputting an acoustic signal to the external auditory canal 2a, and the internal pressure of the external auditory canal 2a is measured by the pressure sensor 14. When a change is detected, a pure tone is output as a calibration sound from the speaker 20 to the external auditory canal 2a, and the measurement data is calibrated using the change in the internal pressure of the external auditory canal 2a due to the output of the calibration sound. Such an operation and effect can be obtained.

  That is, when the sensor unit 10 is attached to the ear canal 2a, even if some air leakage occurs, the measurement data is calibrated by the output of the calibration sound from the speaker 20, so that the pulse sound can be properly measured. Can be.

  As described above, according to the present embodiment, the measurement data of the pulse sound can be calibrated in the body sound measurement system 100.

  Thus, even when the sensor unit 10 is slightly incompletely attached to the external auditory meatus 2a, the pulse sound can be properly measured. Therefore, it is possible to remove the influence of the variation in the mounting state of the sensor unit 10 from the pulse sound measurement data, thereby improving the accuracy of the pulse sound measurement data.

  In the present embodiment, when the <first calibration method> is adopted as a specific calibration method of the pulse sound measurement data, the calibration of the measurement data by the output of the calibration sound from the speaker 20 is performed by measuring the pulse sound. This can be performed so that the amplitude of the data becomes an appropriate value.

  When the <second calibration method> is adopted, not only is the measurement data of the pulse sound calibrated so that its amplitude becomes a proper value, but also the waveform is calibrated so that its waveform approaches a proper shape. be able to.

  When the <third calibration method> is used instead of the <second calibration method>, the measurement data of the pulse sound can be calibrated so that its waveform is closer to an appropriate shape.

  Further, when the <fourth calibration method> is adopted, four types of pure tones having different frequencies are used as calibration sounds, so that the measured data of the pulse sound is simply calibrated so that the amplitude thereof becomes an appropriate value. Instead, it can be calibrated so that its waveform is closer to the proper shape.

  In the body sound measurement system 100 according to the present embodiment, when measuring the pulse sound of the subject 2, a guidance sound regarding the posture of the subject 2 or a sound for guiding the subject 2 to a resting state (for example, It is also possible to output the respiratory rhythm sound) from the speaker 20 of the sensor unit 10. By doing so, the reliability of the measurement data can be further improved. Further, application to a home health care device in which the subject 2 measures the pulse sound alone can be easily performed.

  Further, in the body sound measurement system 100 according to the present embodiment, it is also possible to perform voice communication between the sensor unit 10 and the monitoring unit 110. That is, when a doctor or the like is monitoring at a position distant from the subject 2, the sound in the ear canal of the subject 2 is collected by the pressure sensor 14 of the sensor unit 10, while the sound on the monitoring side is output from the speaker 20. , It is possible to perform voice communication.

  In the above embodiment, the ear tip 16 of the sensor unit 10 has been described as being configured so that the ear canal 2a is a closed space when properly inserted into the ear canal 2a of the subject 2. Instead of a simple structure, it is also possible to adopt a structure having an air vent structure (air vent structure) for reducing the feeling of pressure when the device is mounted on the external auditory meatus 2a. When such an ear tip is employed, the external auditory canal 2a does not become a closed space, but the pulse data can be properly measured by employing the measurement data calibration method according to the present embodiment.

  Although the body 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 unit 110, the sensor unit 10 and the monitoring unit 110 May be connected by a cord or the like.

  In the above-described embodiment, the case where the pressure sensor 14 is an electret condenser microphone has been described. However, other microphones (for example, an electrodynamic microphone having a ventilation hole formed in a space behind the diaphragm) may be employed. is there.

  In the above embodiment, the case where the speaker 20 is a balanced armature type speaker has been described. However, other speakers (for example, electrodynamic type speakers) may be employed.

  It should be noted that the numerical values shown as specifications in the above embodiment are merely examples, and they may be set to different values as appropriate.

  The invention of the present application is not limited to the configuration and method described in the above embodiment, and a configuration and a method in which various other changes are added can be adopted.

2 Subject 2a External auditory canal 4 Coupler 4a Simulated space 10 Sensor unit 12 Housing 12a Sound conduction hole 12A Front member 12Aa Front end wall 12Ab Small diameter cylindrical portion 12Ac Rear end surface 12Ad Inner peripheral surface 12B Rear member 12Ba Front end surface 12Bb Rear end wall 14 Sensor 14a, 20a Terminal portion 16 Ear tip 16a, 34b Through hole 16A, 16B Flange portion 18 Gasket 18a First through hole 18b Second through hole 20 Speaker 22 Diaphragm 22a Micro hole 24, 52 Housing 24a Sound collecting hole 24b Vent hole 26 Sound collecting nozzle 26a Opening 28 Cylindrical member 32 Support ring 34 Back electrode plate 34a Electret layer 36 Spacer 38 Conducting member 40 Insulating member 42 Impedance conversion element 44 Conductive cover 44a Ring-shaped bent portion 46 Circuit board 2a sound emission hole 54 sound emission nozzle 60 signal processing circuit unit 70 battery 100 biological sound measurement system 110 monitoring unit C internal space Cf front space Cr back space C1 first space C2 second space L1 characteristic curve L2 frequency correction straight line (correction) curve)
L3 Frequency correction curve (correction curve)
L4 correction curve

Claims (5)

A body configured to measure the body sound of the subject by detecting a change in the internal pressure of the ear canal by the pressure sensor while the sensor unit having the pressure sensor is attached to the ear canal of the subject. In the sound measurement system, a method of calibrating the measurement data of the body sound,
On the sensor unit, a speaker having a configuration capable of outputting an acoustic signal to the ear canal is provided.
When detecting a change in the internal pressure of the external auditory canal by the pressure sensor, a pure sound is output from the speaker to the external auditory canal as a calibration sound, and the measurement data is calibrated using the internal pressure change of the external auditory canal due to the output of the calibration sound. A method for calibrating measurement data in a body sound measurement system, characterized in that: Prepare a coupler having a simulated space having substantially the same volume as the ear canal in a state where the sensor unit is mounted, and from the speaker in a state where the simulated space is completely enclosed by mounting the sensor unit on this coupler. After setting the amplitude of the calibration sound detected by the pressure sensor when outputting the calibration sound to the simulation space as a reference level,
In the state where the sensor unit is intentionally attached to the ear canal so that air leakage occurs, the speaker performs the preliminary operation of preliminary detecting a change in the internal pressure of the ear canal by the pressure sensor, and outputs the calibration sound from the speaker. The first time domain and the second time domain in which the calibration sound is not output from the speaker are included, and the sensor unit is repeatedly attached and detached a plurality of times,
From the calibration sound and the body sound detected by the plurality of preliminary operations, an approximate expression indicating a relationship between the amplitude of the calibration sound and the amplitude of the body sound is derived. After calculating the reference level of the amplitude of the body sound corresponding to the reference level of the amplitude,
Create a characteristic curve indicating the relationship between the amount of attenuation of the amplitude of the calibration sound from the reference level and the amount of attenuation of the body sound from the reference level, and calibrate the measurement data based on the characteristic curve. The method for calibrating measurement data in the body sound measurement system according to claim 1, wherein the calibration is performed. Performing this operation of actually detecting a change in internal pressure of the ear canal by the pressure sensor with the sensor unit attached to the ear canal so that the first and second time regions are included,
Based on the calibration sound and the body sound detected by this operation, the attenuation amount from the reference level of the body sound amplitude corresponding to the attenuation amount from the reference level of the amplitude of the calibration sound is Calculated from the characteristic curve,
3. The body sound measurement system according to claim 2, wherein the amplitude of the calculated attenuation amount is added to the amplitude of the body sound detected by the pressure sensor to obtain measurement data of the body sound. Calibration method of measurement data. Performing this operation of actually detecting a change in internal pressure of the ear canal by the pressure sensor with the sensor unit attached to the ear canal so that the first and second time regions are included,
Based on the calibration sound and the body sound detected by this operation, the attenuation amount from the reference level of the body sound amplitude corresponding to the attenuation amount from the reference level of the amplitude of the calibration sound is Calculated from the characteristic curve,
On the assumption that the amplitude of the calculated attenuation is the attenuation of the amplitude of the pure tone at the frequency calculated as the reciprocal of the cycle of the body sound,
From the attenuation of the amplitude of the pure sound and the frequency of the pure sound and the attenuation of the amplitude of the calibration sound and the frequency of the calibration sound, create a correction curve indicating the correction amount of the amplitude of the body sound according to the frequency, The body sound measurement system according to claim 2, wherein a waveform obtained by adding the correction amount for each frequency to the waveform of the body sound based on the correction curve is used as measurement data of the body sound. Calibration method of measurement data. A coupler having a simulated space having substantially the same volume as the ear canal in a state where the sensor unit is mounted is prepared, and the speaker is mounted in a state where the simulated space is completely enclosed by mounting the sensor unit on the coupler. After setting the amplitude of each calibration sound detected by the pressure sensor when outputting a plurality of pure sounds having different frequencies as the calibration sound from the simulation space, as a reference level of each calibration sound,
This operation of actually detecting a change in the internal pressure of the ear canal by the pressure sensor in a state where the sensor unit is mounted on the ear canal is performed by a first time domain in which the calibration sound is output from the speaker and the speaker from the speaker. Performed so that the second time domain in which each calibration sound is not output is included,
Based on each of the calibration sounds detected by this operation, the amount of attenuation of the amplitude of each of the calibration sounds from each of the reference levels is calculated,
From the attenuation amount of the amplitude of each of these calibration sounds, a correction curve indicating the correction amount of the amplitude of the body sound according to the frequency is created, and the waveform of the body sound is generated for each frequency based on the correction curve. 2. The method for calibrating measurement data in a body sound measurement system according to claim 1, wherein a waveform obtained by adding the correction amount is used as the measurement data of the body sound.

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