Biological sound measuring device, control method for biological sound measuring device and control program for biological sound measuring device

Abstract

Biological sound measuring device (1), comprising: a sound collecting unit (3) that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit (42) which determines whether a contact state in which the sound collecting unit (3) is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit (3), wherein the contact state determining unit (42) determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value, the sound pressure level decreases by a value equal to or greater than a second threshold value and smaller than the first threshold value.

Description

TECHNICAL FIELD

[0001] The present invention relates to a biological sound measuring device which comes into contact with a body surface of a living body during use, and to a control method and a control program for the biological sound measuring device. STATE OF THE ART

[0002] A known device uses a microphone to extract an electrical signal of biological sound, including: respiratory sounds, which are physiological sounds resulting from the airflow in an airway induced by respiration; accessory sounds, which are abnormal sounds caused by a disease, such as wheezing and pleural friction; and heart sounds, which are derived from the cardiovascular system (see, for example, Patent Documents 1 to 3).

[0003] Patent Document 1 describes a breath measuring device for detecting breath sounds, in which it is determined whether the measuring device is attached by using a light source arranged inside a sound collecting element and a photodetector provided outside the sound collecting element.

[0004] Patent Document 2 describes a biological sound collecting device in which a contact sensor that detects contact of a sound collecting unit on a surface of a living body is used to determine the contact state of the sound collecting unit with respect to the surface of the living body.

[0005] Patent Document 3 describes a technique in which an optimal mounting position for a device is determined by comparing a plurality of sounds measured by a single microphone at different locations or by comparing a plurality of sounds measured by a plurality of microphones mounted at different locations.

[0006] Patent Document 4 provides an electronic stethoscope that can appropriately perform auscultation while reducing noise that is unpleasant to the listener. The electronic stethoscope includes: a sensor unit for detecting sound by bringing it into contact with a subject's body surface; an output unit that changes the level of a sound signal with respect to the sound detected by the sensor unit and outputs an output signal; and control units that control the output unit. The control units control the output unit so that the level of the output signal decreases for a first predetermined time from the time the sensor unit is brought into contact with the subject.

[0007] Patent Document 5 describes a vital signs detection device comprising a sound detection unit and a pressure unit. The sound detection unit senses a sound in a user's body and generates an audio signal. The pressure unit generates a pressure signal. The pressure signal indicates the degree of proximity between the vital signs detection device and the user. The audio signal is converted into a processed audio signal corresponding to the pressure signal.

[0008] Patent Document 6 describes a power supply circuit of a wearable electronic biosensor. The power supply circuit implements conditional power supply logic to control the power consumption of the biosensor and distinguish between intended use and non-use of the biosensor by a clinician. The biosensor is configured to detect a property of the human body, such as a manifestation of acoustic energy generated by matter of biological origin or an action potential of the human body.

[0009] Patent Document 7 describes a stethoscope comprising: a stethoscope part including a chestpiece and a microphone provided inside the chestpiece or in a hollow tube connected to the chestpiece; and sensors for detecting contact with a human body, the sensors detecting contact by abutting against the body and being attached to the chestpiece such that, when in a state where contact is detected, the abutting ends of the sensors are arranged in the same position as the contact surface of the chestpiece against the body or in a position slightly farther from the body than the contact surface. LIST OF CITATIONS Patent literature Patent Document 1: JP 2017-74190 A Patent Document 2: JP 2015-20030 A Patent Document 3: JP 2012-24391 A Patent document 4: WO 2017 / 042 875 A1 Patent document 5: US 2015 / 0 088 021 A1 Patent document 6: US 2008 / 0232 604 A1 Patent document 7: WO 2017 / 159 752 A1 SUMMARY OF THE INVENTIONTechnical problem

[0010] In a biological sound measuring device that contacts a body surface of a living body and measures biological sound, analysis processing of a sound measured by a sound collecting unit is preferably started after an adherent state of the sound collecting unit to the body surface is obtained. Therefore, it is necessary to detect whether the sound collecting unit is in contact with the body surface or not. In the devices described in Patent Documents 1 and 2, a dedicated device such as a photodetector or a contact sensor is required to determine the contact state with the body surface, which makes it difficult to reduce the size, weight, and cost of the device.

[0011] In the device described in Patent Document 3, the contact state with the body surface cannot be easily determined because sound is measured from different positions on the body surface and a plurality of microphones are required.

[0012] The present invention has been made in view of the above circumstances, and the present invention relates to the provision of: a biological sound measuring device capable of detecting contact with a body surface of a living body with a simple configuration; a control method for the biological sound measuring device; and a control program for the biological sound measuring device. Solution to the problem

[0013] (1) A biological sound measuring device includes: a sound collecting unit that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit that determines whether a contact state in which the sound collecting unit is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit, wherein the contact state determining unit determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold, the sound pressure level decreases by a value equal to or greater than a second threshold and smaller than the first threshold.

[0014] According to (1), the contact state is determined based on a change in the sound pressure level of the sound detected by the sound collection unit. Accordingly, the contact state can be determined without using a dedicated device such as a light-emitting unit or a contact sensor, and without detecting biological sound under various conditions. Thus, the cost, size, and weight of the device can be reduced.

[0015] According to (1), the contact state can be determined with high accuracy.

[0016] (2) A biological sound measuring device comprises: A sound collecting unit that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit that determines whether a contact state in which the sound collecting unit is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit, wherein the contact state determining unit determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold and then the sound pressure level decreases by a value equal to or greater than a second threshold and less than the first threshold, a fluctuation amount of the sound pressure level is equal to or less than a third threshold continuously for a predetermined period of time.

[0017] According to (2), the contact state can be determined with high accuracy.

[0018] (3) A biological sound measuring device comprises: A sound collecting unit that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit that determines whether a contact state in which the sound collecting unit is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit, wherein the contact state determining unit determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold and then the sound pressure level decreases by a value equal to or greater than a second threshold and smaller than the first threshold, it is determined that a biological sound detected by the sound collecting unit is collected.

[0019] According to (3), the contact state can be determined with high accuracy.

[0020] (4) The biological sound measuring device according to (1) to (3) has a configuration wherein the contact state determination unit determines whether or not a contact state in which the sound collecting unit is in contact with the body surface is active based on a change in a sound pressure level of a specific frequency band of sound detected by the sound collecting unit.

[0021] According to (4), the contact state can be determined with high accuracy.

[0022] (5) The biological sound measuring device according to (4), wherein the specific frequency band is a frequency band of 100 Hz and below.

[0023] According to (5), the contact state can be determined with high accuracy.

[0024] (6) The biological sound measuring device according to any one of (1) to (5), further includes: a control unit that analyses sound detected by the sound collection unit and notifies of an analysis result, whereby the control unit starts analyzing the sound in a case where the contact state determining unit determines that the contact state is active.

[0025] According to (6), sound analysis is initiated simply by the measuring operator bringing the sound pickup unit into contact with the body surface of the living body. As a result, the analysis of biological sound can begin easily, smoothly, and intuitively.

[0026] (7) The biological sound measuring device according to (6) has a configuration wherein the control unit analyzes the sound and notifies an analysis result indicating whether or not wheezing is included in the sound.

[0027] Since the measuring personnel is notified of the presence or absence of wheezing, a treatment strategy for the subject can be planned according to (7).

[0028] (8) A control method for a biological sound measuring device includes: determining, based on a change in a sound pressure level of sound detected by the sound collecting unit, whether a contact state in which a sound collecting unit of a biological sound measuring device, the sound collecting unit detecting a biological sound of a living body in a contact state with a body surface of the living body, is in contact with the body surface is active or not, wherein in determining, the contact state is determined to be active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value, the sound pressure level decreases by a value equal to or greater than a second threshold value and less than the first threshold value.

[0029] According to (8), the contact state is determined based on a change in the sound pressure level of the sound detected by the sound collection unit. Accordingly, the contact state can be determined without using a dedicated device such as a light-emitting unit or a contact sensor, and without detecting biological sound under various conditions. Thus, the cost, size, and weight of the device can be reduced.

[0030] (9) A non-transistor recording medium containing a control program for a biological sound measuring device to cause a computer to perform the following: Determining, based on a change in a sound pressure level of sound detected by the sound collecting unit, whether a contact state in which a sound collecting unit of a biological sound measuring device, wherein the sound collecting unit detects a biological sound of a living body in a contact state with a body surface of the living body, is in contact with the body surface is active or not, wherein in determining, the contact state is determined to be active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value, the sound pressure level decreases by a value equal to or greater than a second threshold value and less than the first threshold value.

[0031] According to (9), the contact state is determined based on a change in the sound pressure level of the sound detected by the sound collection unit. Accordingly, the contact state can be determined without using a dedicated device such as a light-emitting unit or a contact sensor, and without detecting biological sound under various conditions. Thus, the cost, size, and weight of the device can be reduced. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0032] The present invention can provide: a biological sound measuring device capable of detecting contact with a body surface of a living body with a simple configuration; a control method for the biological sound measuring device; and a control program for the biological sound measuring device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view illustrating a schematic example configuration of a biological sound measuring device 1, which is an embodiment of the biological sound measuring device of the present invention. Fig. 2 is a schematic cross-sectional view along the line AA of the Fig. 1 illustrated biological sound measuring device 1. Fig. 3 is a diagram showing functional blocks of a control unit 4 of the Fig. 1 illustrated biological sound measuring device 1. Fig. 4 is a diagram showing an example of changes in the sound pressure level of the sound detected by a sound detection element M1 of the biological sound measuring device 1. Fig. 5 is a flowchart for describing an operation example of the Fig. 1 illustrated biological sound measuring device 1. Fig. 6 is a flowchart for describing a modified example of operations performed after YES is determined in step S9 of the flowchart of FIF. 5. Fig. Fig. 7 is a flowchart for describing a modified example of operations executed after YES in step S9 of the flowchart of Fig. 5 is determined. Fig. 8 is a diagram showing an example of a power spectrum obtained by Fourier transform of the sound detected by the sound detection element M1 of the biological sound measuring device 1 in a non-contact state. Fig. 9 is a diagram showing an example of a power spectrum obtained by Fourier transform of the sound detected by the sound detection element M1 of the biological sound measuring device 1 in a contact state. DESCRIPTION OF THE EMBODIMENTS

[0033] Overview of a Biological Sound Measuring Device According to an Embodiment An overview of a biological sound measuring device according to an embodiment of the present invention will now be described. The biological sound measuring device of one embodiment measures lung sounds (breathing sounds and peripheral sounds) as an example of biological sound via a measuring unit configured to be placed on a region between the ribs of a person. In a case where it is determined that wheezing is included as a peripheral sound in the measured sound, the biological sound measuring device outputs a notification thereof. In this way, it assists in determining whether or not a subject needs to be administered medication, whether or not a subject should be hospitalized, and in diagnosing a subject by a doctor.

[0034] The biological sound measuring device of one embodiment includes the measuring unit, which includes a housing in which a sound detection element for detecting lung sounds is housed. The biological sound measuring device detects lung sounds of a living body by sealing the space within the housing in which the sound detection element is housed with a body surface and, in this state, detecting pressure fluctuations in the space by the sound detection element.

[0035] The biological sound measuring device of one embodiment monitors a sound pressure level of the sound detected by the sound detection element and determines whether or not the measuring unit is in a contact state with the body surface of the living body based on the changes in the sound pressure level. As described above, since the contact state is determined based on the sound pressure level of the sound detected by the sound detection element used for detecting lung sounds, a dedicated device for determining the contact state and detecting sounds under various conditions is not required. Thus, the cost, size, and weight of the device can be reduced. A specific example of the configuration of a biological sound measuring device according to one embodiment will be described below. Embodiment

[0036] Fig. 1 is a side view illustrating a schematic example configuration of a biological sound measuring device 1, which is an embodiment of the biological sound measuring device of the present invention. As shown in Fig. 1, the biological sound measuring device 1 includes: a body portion 1b which is a container made of resin or metal; and a head portion 1a provided on a first end side of the body portion 1b.

[0037] The body portion 1b is provided with: a control unit 4 that performs overall control, a battery 5 that supplies the necessary voltage for operation, and a display unit 6 that displays images via a liquid crystal display panel, an organic electroluminescence (EL) display panel, or the like.

[0038] The control unit 4 includes a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), and the like, and controls each hardware component of the biological sound measuring device 1 according to a program. The ROM of the control unit 4 stores a program including a control program for the biological sound measuring device 1.

[0039] The head section 1a is provided with a measuring unit 3, which leads to a first side (in Fig. 1 downward) in a direction approximately orthogonal to the longitudinal direction of the biological sound measuring device 1. The front end of the measuring unit 3 is provided with a pressure receiving unit 3a, which is brought into contact with a body surface S of a living body, ie, a subject, and receives pressure from the body surface S.

[0040] The biological sound measuring device 1 is used by pressing the pressure receiving unit 3a of the measuring unit 3 against the body surface S with the index finger of a user's hand Ha, with the index finger being placed on the back of the measuring unit 3 at the head portion 1a.

[0041] Fig. 2 is a schematic cross-sectional view along the line AA of the Fig. 1. The measuring unit 3 is provided with: a housing 31 with a closed bottom, which is a member forming a housing space SP1 sealed by the body surface S when pressure is applied thereto; a sound detection element M1 that detects sound disposed in the housing space SP1 of the housing 31; and a housing cover 32 that closes the housing space SP1 to the outside and covers the housing 31.

[0042] The measuring unit 3 is engaged with an opening portion formed on a housing 2 constituting the head portion 1a and is fixed to the housing 2 with a portion of the housing cover 32 exposed.

[0043] The front end portion of the case cover 32 of the portion exposed from the case 2 is shaped as a flat surface or a curved surface, this flat surface or curved surface being the Fig. 1 forms the pressure receiving unit 3a shown.

[0044] The outer shape of the housing 31 is in Fig. 2, approximately a downward-facing protrusion-like shape. The housing 31 is made of a material, such as a resin or metal, that has a higher acoustic impedance than air and high rigidity. The housing 31 is preferably made of a material that reflects sound in a measurement frequency range of the sound detection element M1, so that transmission of sound from the outside within the housing space SP1 is made difficult when the housing 31 is in contact with the body surface S.

[0045] The housing cover 32 is a cylindrical member with a closed bottom, and the shape of the hollow portion of the housing cover 32 is substantially the same as the outer wall shape of the housing 31.

[0046] The housing cover 32 is made of a material with an acoustic impedance close to that of the human body, air, or water, and exhibits good flexibility and good biocompatibility. Examples of the material of the housing cover 32 include silicone, an elastomer, and the like.

[0047] The sound detection element M1 is configured to detect lung sounds, that is, the measurement target of the biological sound measuring device 1, and is composed of, for example, a microelectromechanical system (MEMS) microphone or a capacitance type microphone that detects sound in a band (for example, a frequency range in the range of 1 Hz to 10 kHz) wider than the frequency range (typically a range of 10 Hz to 1.5 kHz) of lung sounds.

[0048] The sound detection element M1 is connected to the Fig. 1 illustrated control unit 4 by a non-illustrated conducting wire and transmits the detected sound information to the control unit 4.

[0049] To use the biological sound measuring device 1, the pressure recording unit 3a of the housing cover 32 is brought into contact with the body surface S, and under pressure from the body surface S, the housing space SP1 is closed by the body surface S via the housing cover 32. If the pressure recording unit 3a vibrates due to the lung sounds transmitted from the living body to the body surface S, the internal pressure of the housing space SP1 fluctuates due to this vibration, and this fluctuation in the internal pressure causes an electrical signal corresponding to the lung sound to be detected by the sound detection element M1. The measuring unit 3 forms a sound recording unit for detecting biological sound upon contact with the body surface S.

[0050] Fig. 3 is a diagram showing functional blocks of the control unit 4 of the Fig. 1. The processor of the control unit 4 functions as a contact state determination unit 41 and a control unit 42 by executing the above-described control program stored in the ROM.

[0051] The contact state determination unit 41 determines whether the measuring unit 3 is in contact with the body surface S or not based on the sound pressure level of the sound detected by the sound detection element M1.

[0052] Fig. 4 is a diagram showing an example of changes in the sound pressure level of the sound detected by the sound detection element M1 of the biological sound measuring device 1. In Fig. 4 shows the changes in the sound pressure level obtained when the pressure receiving unit 3a of the measuring unit 3 comes into contact with the body surface S from a non-contact state with the body surface S, the pressure receiving unit 3a is held in this state for a while, and then the pressure receiving unit 3a is separated from the body surface S and put into a non-contact state.

[0053] One in Fig. The time period T1 shown in Fig. 4 indicates a time period in which the pressure receiving unit 3a of the measuring unit 3 is not in contact with the body surface S. A time period shown in Fig. 4 indicates a period of time immediately after the pressure receiving unit 3a of the measuring unit 3 is brought into contact with the body surface S. A period of time T2 shown in Fig. The period T3 shown in Figure 4 indicates a period in which the pressure receiving unit 3a of the measuring unit 3 is in contact with the body surface S and is maintained in this state. Fig. The period T4 shown in Figure 4 indicates a period immediately after the pressure receiving unit 3a of the measuring unit 3 is separated from the body surface S and placed in a non-contact state. Fig. 4 indicates a period of time after a short time has elapsed since the pressure receiving unit 3a of the measuring unit 3 was placed in a non-contact state with the body surface S.

[0054] As in Fig. As shown in Figure 4, in the period T1 and the period T5 in which the pressure receiving unit 3a is not in contact with the body surface S, the sound pressure level of the sound detected by the sound detecting element M1 shifts to a low value. This is because when the pressure receiving unit 3a is not in contact with an object, the vibration of the pressure receiving unit 3a does not increase unless a large sound is generated near the biological sound measuring device 1.

[0055] When there is a transition from a state in which the pressure receiving unit 3a is not in contact with the body surface S to a state in which the pressure receiving unit 3a is in contact with the body surface S, immediately after this transition, the vibrations of the pressure receiving unit 3a increase because the pressure receiving unit 3a and the body surface S come into contact. Thus, the sound pressure levels reach, as shown in Fig. 4, temporarily high values ​​at the time T2. After a short time has elapsed since the contact between the pressure recording unit 3a and the body surface S, the pressure recording unit 3a vibrates mainly due to the biological sound transmitted to the body surface S. Therefore, as shown in Fig. 4, in period T3, after a short time has elapsed since the contact between the pressure recording unit 3a and the body surface S, the sound pressure levels are lower than in period T2. Here, the sound pressure level during period T3 has values ​​that are greater than the sound pressure level during period T1, since the pressure recording unit 3a is caused to vibrate by the biological sound.

[0056] During the transition from a state in which the pressure receiving unit 3a is in contact with the body surface S and is held thereto to a state in which the pressure receiving unit 3a is separated from the body surface S, immediately after this transition the vibrations of the pressure receiving unit 3a increase due to the separation of the pressure receiving unit 3a and the body surface S. Thus, the sound pressure levels reach, as in Fig. 4, temporarily high values ​​at period T4. Then, when a short time elapses since the separation of the pressure recording unit 3a and the body surface S, the sound pressure level transitions to a level similar to the values ​​at period T1.

[0057] Accordingly, it can be seen that when the pressure receiving unit 3a of the measuring unit 3 is brought into contact with the body surface S from a non-contact state with the body surface S and maintained in this state, the sound pressure level of the sound detected by the sound detection element M1 temporarily increases, after which it decreases and stabilizes at a level higher than the sound pressure level during the non-contact state. Thus, it can be determined whether or not a contact state exists by determining whether or not such changes in the sound pressure levels exist.

[0058] Specifically, when sound detection by the sound detection element M1 is started and storage of the sound pressure level information in the RAM is started, the contact state determination unit 41 obtains the sound pressure level information for each unit processing period (for example, several ms or several tens of ms) from the sound detection start time from the RAM and calculates the average of the obtained sound pressure levels. The contact state determination unit 41 sequentially advances from the start time of the unit processing period by a time period shorter than the unit processing period, for example, and sequentially calculates the average of the sound pressure levels of each unit processing period.

[0059] The contact state determination unit 41 compares a first average value calculated for a freely selected unit period with a second average value calculated for a unit period after the unit period has been advanced by one, and determines that a transition from a non-contact state to a contact state has occurred in a case where the second average value is greater than the first average value by a value greater than or equal to a predetermined first threshold value. In a case where the second average value is not greater than the first average value by a value greater than or equal to the first threshold value, the contact state determination unit 41 determines that a non-contact state is active in which the measuring unit 3 is not in contact with the body surface S.

[0060] The first threshold is determined empirically as the minimum value of a value obtained by calculating the difference between the mean sound pressure level in period T1 and the mean sound pressure level in period T2, as for example in Fig. 4. In addition, the first threshold value is set to a value sufficiently larger than a value obtained by calculating the difference between the mean value of the sound pressure level in the period T3 and the mean value of the sound pressure level in the period T4 shown in Fig. 4 shown period T4.

[0061] Even after the contact state determination unit 41 determines that a transition from a non-contact state to a contact state has occurred, a comparison of the second average value of the sound pressure levels in the last unit processing period with the last start time with the first average value of the sound pressure levels in the unit processing period before the last unit processing period is repeated. In a case where the second average value is equal to or greater than a second threshold but less than the first threshold, the contact state determination unit 41 then determines that a contact state in which the measuring unit 3 has come into contact with the body surface S is active.Note that in a case where the second average value is smaller than the first average value by a value equal to or larger than the first threshold value, the contact state determination unit 41 determines that a transition to a contact state has ended and a non-contact state has returned.

[0062] The second threshold value is determined empirically as a value obtained by subtracting a maximum value from a value obtained by calculating the difference between the mean value of the sound pressure level in the period T3 and the mean value of the sound pressure level in the period T4. Fig. 4, from the first threshold value.

[0063] The control unit 42 performs analysis processing to analyze the sound detected by the sound detection element M1 and notification processing to output a notification of the result of the analysis processing (analysis result). The analysis processing is for example: processing the sound detected by the sound detection element M1 and determining whether or not an abnormal sound such as wheezing is included in the sound. The notification processing is for example processing that includes: notifying the analysis result by displaying the presence or absence of wheezing on the display unit 6, notifying the presence or absence of wheezing by lighting up a light-emitting element (not shown), and the like.

[0064] In a case where the contact state determination unit 41 determines that the measuring unit 3 is in a contact state, the control unit 42 starts the analysis processing described above. Operational example of the biological sound measuring device 1

[0065] Fig. 5 is a flowchart for describing an operation example of the Fig. 1. When the device is turned on, sound detection is started by the sound detection element M1, and the detected sound information (including the sound pressure level) and the sound detection time information are stored in the RAM (step S1).

[0066] When the sound information for a certain period of time is stored in the RAM, the contact state determination unit 41 obtains the sound pressure levels of the sound detected in the information during the unit processing period and calculates the average of the obtained sound pressure level (step S2). Note that in the initial setting, the unit processing period is set so that the start time of the unit processing period coincides with the start time of the sound information stored in the RAM.

[0067] Next, the contact state determination unit 41 advances the start time of the unit processing period (postpones the unit processing period) and resets the unit processing period (step S3). Then, the contact state determination unit 41 obtains what is detected in the set unit processing period and calculates the average of the obtained sound pressure levels from the sound pressure levels stored in the RAM (step S4).

[0068] Next, the contact state determination unit 41 determines whether the value obtained by subtracting, from the average value (average value after shift) of the sound pressure levels corresponding to the last set unit processing period calculated in step S4, the average value (average value before shift) of the sound pressure levels corresponding to the unit processing period set immediately before the last setting is equal to or greater than a first threshold value TH1 (step S5).

[0069] In a case where the determination of step S5 is NO, the contact state determination unit 41 determines that a non-contact state is active in which the measuring unit 3 is not in contact with the body surface S (step S6), and the process proceeds to step S3.

[0070] If the determination of step S5 is YES, the contact state determination unit 41 advances the start time of the unit processing period (postpones the unit processing period) and resets the unit processing period (step S7). Then, the contact state determination unit 41 obtains what is detected in the set unit processing period and calculates the average of the obtained sound pressure levels from the sound pressure levels stored in the RAM (step S8).

[0071] Next, the contact state determination unit 41 determines whether a difference (absolute value without sign) between the average value (average value after shift) of the sound pressure levels corresponding to the last set unit processing period calculated in step S8 and the average value (average value before shift) of the sound pressure levels corresponding to the unit processing period set immediately before the last setting is equal to or greater than a second threshold value TH2 and smaller than the first threshold value TH1 (step S9).

[0072] In a case where the determination of step S9 is NO, the contact state determination unit 41 determines whether or not the above-described difference is equal to or greater than the first threshold TH1 (step S10). In a case where the above-described difference is equal to or greater than the first threshold TH1 (YES in step S10), the contact state determination unit 41 shifts the process to step S6, and in a case where the above-described difference is smaller than the first threshold TH1 (NO in step S10), the contact state determination unit 41 shifts the process to step S7.

[0073] In a case where the determination of step S9 is YES, the contact state determination unit 41 determines that a contact state suitable for biological sound measurement is active in which the measuring unit 3 is in contact with the body surface S (step S11).

[0074] After step S11, the control unit 42 starts the analysis processing on the sound detected by the sound detection element M1 (step S12), and when the analysis processing is finished, the control unit 42 outputs a notification of the analysis result (step S13) and the process ends. Effect of the biological sound measuring device 1

[0075] As described above, the biological sound measuring device 1 determines whether a contact state exists or not based on a change in the sound pressure level of the sound detected by the sound detection element M1. Accordingly, the contact state can be determined with a simple configuration, without using a dedicated device such as a light-emitting unit or a contact sensor, and without detecting sound under various conditions. Thus, the cost, size, and weight of the device can be reduced.

[0076] Furthermore, according to the biological sound measuring device 1, it is determined that a contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than the first threshold TH1, the sound pressure level decreases by a value equal to or greater than the second threshold TH2 but smaller than the first threshold TH1, where the second threshold TH2 is smaller than the first threshold TH1. By determining that a contact state is active in a case where, after the sound pressure level sharply increases, the sound pressure level decreases to a level higher than the sound pressure level before the increase, an accurate distinction can be made between the case of a transition from the period T3 to the period T5 and the case of a transition from the period T1 to the period T3, which is Fig. 4. Accordingly, it can be determined with high accuracy whether a contact condition exists or not.

[0077] Furthermore, according to the biological sound measuring device 1, in a case where a contact state is determined to be active, analysis processing of sound is started. According to this configuration, the measuring person can know whether wheezing is present simply by pressing the measuring unit 3 against the body surface S of the subject, and no special operation is required after turning on the device. Thus, the convenience of the device is improved. Furthermore, since a user interface such as a button for issuing an instruction to start analysis processing is not required, the design of the device can be improved and the cost of the device can be reduced. The biological sound measuring device 1 is used by grasping the body portion 1b with one hand and placing the index finger on the back of the measuring unit 3.Thus, the ability to start the analysis processing by simply bringing the measuring unit 3 into contact with the body surface S is effective to stabilize the contact state with the body surface S. First modified example of the biological sound measuring device 1

[0078] After YES in step S9 of Fig. 5, the contact state determining unit 41 may determine that a contact state is active in a case where a slight fluctuation in the sound pressure levels is continuously present for a predetermined period of time.

[0079] Fig. Fig. 6 is a flowchart for describing a modified example of operations executed after YES in step S9 of the flowchart of Fig. 5 is intended. In Fig. 6, the same reference numerals are used for the same processing as in Fig. 5 used.

[0080] If the determination of step S9 is YES, the contact state determination unit 41 advances the start time of the unit processing period (postpones the unit processing period) and resets the unit processing period (step S21). Then, the contact state determination unit 41 obtains what is detected in the set unit processing period and calculates the average of the obtained sound pressure levels from the sound pressure levels stored in the RAM (step S22).

[0081] Next, the contact state determination unit 41 determines whether a difference (absolute value without sign) between the average value (average value after shift) of the sound pressure levels corresponding to the last set unit processing period calculated in step S22 and the average value (average value before shift) of the sound pressure levels corresponding to the unit processing period set immediately before the last adjustment is smaller than a third threshold value TH3 (step S23). The third threshold value TH3 is set to determine whether or not the measuring unit 3 is kept in contact with the body surface S, and is a value sufficiently smaller than the first threshold value TH1 and the second threshold value TH2.

[0082] If the determination of step S23 is NO, the contact state determination unit 41 shifts the process to step S6, and if the determination of step S23 is YES, the contact state determination unit 41 increases a timer value by one (step S24). Note that the initial value of the timer value is 0.

[0083] After step S24, the contact state determination unit 41 determines whether the timer value is equal to or greater than a threshold value TH4 (step S25). If the timer value is less than the threshold value TH4 (NO in step S25), the contact state determination unit 41 returns the process to step S21.

[0084] In a case where the timer value is equal to or greater than the threshold value TH4 (YES in step S25), the contact state determination unit 41 shifts the process to step S11.

[0085] As described above, in the first modified example, it is determined that a contact state is active in a case where, after the sound pressure level sharply increases, the sound pressure level decreases to a level higher than the sound pressure level before the increase, and the amount of fluctuation of the sound pressure level after this shift is equal to or less than the third threshold TH3 for a certain continuous period of time. There are cases where, after the measuring unit 3 is brought into contact with the body surface S, the measuring unit 3 is then quickly separated from the body surface S. According to the first modified example, since such cases do not lead to a contact state determination, the accuracy of determining whether a contact state is active or not can be increased. Second modified example of the biological sound measuring device 1

[0086] After YES in step S9 of Fig. 5, the contact state determining unit 41 may determine that a contact state is active in a case where it is determined that a biological sound is included in the sound detected by the sound detecting element M1.

[0087] Fig. Fig. 7 is a flowchart for describing a modified example of operations executed after YES in step S9 of the flowchart of Fig. 5 is intended. In Fig. 7, the same reference numerals are used for the same processing as in Fig. 5 used.

[0088] After determining YES in step S9, the contact state determination unit 41 may perform biological sound determination processing to determine whether or not a biological sound is included in the sound detected by the sound detection element M1 (step S31). For example, the contact state determination unit 41 performs frequency analysis of the sound detected by the sound detection element M1. The contact state determination unit 41 determines that a biological sound is detected in a case where the sound includes a frequency band in which a biological sound can be found, and determines that no biological sound is detected in a case where the sound does not include a frequency band in which a biological sound can be found.

[0089] In a case where the result of the determination processing of step S31 is that no biological sound is detected (NO in step S32), the process proceeds to step S6. In a case where biological sound is detected (YES in step S32), the processing of step S11 is further executed.

[0090] As described above, in the second modified example, it is determined that a contact state is active in a case where, after the sound pressure level sharply increases, the sound pressure level decreases to a level higher than the sound pressure level before the increase, and it is determined that a biological sound is included in the sound detected after this shift. There are cases where, after the measuring unit 3 is brought into contact with the body surface S, the measuring unit 3 is then quickly separated from the body surface S. According to the second modified example, since such cases do not result in a contact state determination, the accuracy of determining whether a contact state is active or not can be increased.

[0091] Third modified example of the biological sound measuring device 1

[0092] The contact state determination unit 41 can determine whether a contact state is active or not based on a change in the sound pressure level of a certain frequency band from the sound detected by the sound detection element M1.

[0093] Fig. 8 and Fig. 9 are diagrams showing examples of a power spectrum obtained by a Fourier transform of the sound detected by the sound detection element M1 of the biological sound measuring device 1. Fig. 8 shows measurement results of sound when the measuring unit 3 is not in contact with the body surface S. Fig. 9 shows measurement results of sound when the measuring unit 3 is in contact with the body surface S.

[0094] As in Fig.As can be seen from Figure 9, when the measuring unit 3 is brought into contact with the body surface S, the power increases sharply, especially in the 100 Hz and below frequency band of the detection frequency band (1 Hz to 10 kHz) of the sound detection element M1. This is due to the fact that the housing space SP1 is sealed in the active contact state, and the sensitivity of the low-frequency range increases.

[0095] Based on this recognition, the contact state determination unit 41 sets a frequency band of, for example, 100 Hz and below as the specific frequency band, and calculates the effective value (RMS value) of the power in the specific frequency band of the sound detected by the sound detection element M1 as the sound pressure level. Then, the contact state determination unit 41 determines that a contact state is active in a case where a state of the effective value greater than a predetermined threshold continues for a certain period of time.

[0096] As described above, according to the third modified example, when determining the contact state, only the sound pressure level of the specific frequency band is monitored. As a result, it is possible to eliminate the effects of noise occurring in high-frequency bands and increase the accuracy of determining the contact state. Note that the upper limit of the specific frequency band can be determined by considering the degree of sound pressure rise and noise elimination in the contact state, and can be 200 Hz, 90 Hz, 80 Hz, 70 Hz, or the like.

[0097] Although various embodiments have been described with reference to the drawings, it should be understood that the present invention is not limited to such examples.

[0098] This application is based on Japanese patent application filed on February 6, 2019 (Japanese Patent Application 2019-020130), the contents of which are incorporated herein by reference. List of reference symbols 1 Biological sound measuring device 1b Body section 1a Head section 2 containers 3 measuring unit 3a Pressure recording unit 4 Control unit 41 Contact state determination unit 42 Control unit 5 Battery 6 Display unit S body surface Ha Hand 31 housings SP1 housing space 32 Housing cover M1 sound detection element

Claims

[1] Biological sound measuring device (1), comprising: a sound collecting unit (3) that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit (42) which determines whether a contact state in which the sound collecting unit (3) is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit (3), wherein the contact state determining unit (42) determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value, the sound pressure level decreases by a value equal to or greater than a second threshold value and smaller than the first threshold value. [2] Biological sound measuring device (1) comprising: a sound collecting unit (3) that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit (42) which determines whether a contact state in which the sound collecting unit (3) is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit (3), wherein the contact state determination unit (42) determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value and then the sound pressure level decreases by a value equal to or greater than a second threshold value and less than the first threshold value, a fluctuation amount of the sound pressure level is equal to or less than a third threshold value continuously for a predetermined period of time. [3] Biological sound measuring device (1) comprising: a sound collecting unit (3) that detects a biological sound of a living body in a contact state with a body surface of the living body; and a contact state determination unit (42) which determines whether a contact state in which the sound collecting unit (3) is in contact with the body surface is active or not based on a change in a sound pressure level of sound detected by the sound collecting unit (3), wherein the contact state determining unit (42) determines that the contact state is active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value and then the sound pressure level decreases by a value equal to or greater than a second threshold value and less than the first threshold value, it is determined that a biological sound is being recorded which is detected by the sound collecting unit (3). [4] The biological sound measuring device (1) according to any one of claims 1 to 3, wherein the contact state determining unit (42) determines whether or not a contact state in which the sound collecting unit (3) is in contact with the body surface is active based on a change in a sound pressure level of a specific frequency band of sound detected by the sound collecting unit (3). [5] The biological sound measuring device (1) according to claim 4, wherein the specific frequency band is a frequency band of 100 Hz and below. [6] The biological sound measuring device (1) according to any one of claims 1 to 5, further comprising a control unit (4) that analyzes sound detected by the sound collecting unit (3) and notifies an analysis result, wherein the control unit (4) starts analyzing the sound in a case where the contact state determining unit (42) determines that the contact state is active. [7] The biological sound measuring device (1) according to claim 6, wherein the control unit (4) analyzes the sound and notifies an analysis result indicating whether or not wheezing is included in the sound. [8] Control method for a biological sound measuring device (1), comprising: Determine, based on a change in a sound pressure level of sound, which is detected by the sound collecting unit (3), whether a contact state in which a sound collecting unit (3) of a biological sound measuring device (1), wherein the sound collecting unit (3) detects a biological sound of a living body in a contact state with a body surface of the living body, is in contact with the body surface, is active or not, wherein in determining, the contact state is determined to be active in a case where, after the sound pressure level increases by a value equal to or greater than a first threshold value, the sound pressure level decreases by a value equal to or greater than a second threshold value and less than the first threshold value. [9] Non-transistor recording medium storing a control program for a biological sound measuring device (1) for causing a computer to perform the following: Determining, based on a change in a sound pressure level of sound detected by the sound collecting unit (3), whether a contact state in which a sound collecting unit (3) of a biological sound measuring device (1), wherein the sound collecting unit (3) detects a biological sound of a living body in a contact state with a body surface of the living body, is in contact with the body surface, is active or not, wherein in determining the contact state in a case as active, in which, after the sound pressure level increases by a value equal to or greater than a first threshold value, the sound pressure level decreases by a value equal to or greater than a second threshold and less than the first threshold.

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