Biological sound acquisition device, biological sound acquisition method, program, and recording medium

Abstract

A device for acquiring biological sounds according to the present disclosure comprises: a biological sound sensor for acquiring biological sounds of a patient; a first band-limiting circuit for acquiring a first signal having a predetermined frequency band of the biological sounds; a second band-limiting circuit for acquiring a second signal having the predetermined frequency band of the biological sounds and amplified by a predetermined amplification factor; a calculation circuit for calculating a first characteristic value of the first signal including a value related to the sound pressure of the biological sounds, and a second characteristic value obtained by dividing a characteristic value of the second signal by the predetermined amplification factor; and a determination circuit for determining an SN level indicating the signal and noise conditions in the predetermined frequency band of the biological sounds on the basis of the first characteristic value and the second characteristic value.

Description

Body sound acquisition device, body sound acquisition method, program, and recording medium

[0001] The present disclosure relates to a body sound acquisition device, a body sound acquisition method, a program, and a recording medium.

[0002] 2. Description of the Related Art Devices that analyze biological sounds acquired by an electronic stethoscope or the like are known.

[0003] For example, Patent Document 1 discloses a respiratory sound analysis device that includes a first decomposition means that decomposes the spectrum of respiratory sounds, a second decomposition means that decomposes at least a part of the spectrum decomposed by the first decomposition means, and an output means that outputs information regarding the proportion of each of the decomposed spectra contained in the respiratory sounds based on the spectra decomposed by the first decomposition means and the second decomposition means.

[0004] International Publication No. 2016 / 002004

[0005] The respiratory sound analyzer of Patent Document 1 has a problem in that it is not possible to determine the signal-to-noise level of body sounds for accurate diagnosis.

[0006] The present disclosure provides a body sound acquiring device, a body sound acquiring method, a program, and a recording medium that are capable of determining the S / N level of a body sound.

[0007] A body sound acquisition device according to one aspect of the present disclosure comprises: a body sound sensor that acquires the body sound of a patient; a first band-limiting circuit that acquires a first signal having a predetermined frequency band from the body sound; a second band-limiting circuit that acquires a second signal having the predetermined frequency band from the body sound and amplified by a predetermined amplification factor; a calculation circuit that calculates a first characteristic value of the first signal, including a value related to the sound pressure of the body sound, and a second characteristic value obtained by dividing the characteristic value of the second signal by the predetermined amplification factor; and a determination circuit that determines an S / N level that indicates the state of signal and noise in the predetermined frequency band of the body sound based on the first characteristic value and the second characteristic value.

[0008] A body sound acquisition method according to one aspect of the present disclosure is a method for acquiring a patient's body sound and determining the state of the body sound, and includes the steps of: acquiring the patient's body sound; acquiring a first signal having a predetermined frequency band from the acquired body sound; acquiring a second signal having the predetermined frequency band from the acquired body sound and amplified by a predetermined amplification factor; calculating second characteristic values ​​by dividing a first characteristic value of the first signal and a characteristic value of the second signal, each of which includes a value related to the sound pressure of the body sound, by the predetermined amplification factor; and determining an S / N level indicating the state of signal and noise in the predetermined frequency band of the body sound based on the first characteristic value and the second characteristic value.

[0009] A program according to one aspect of the present disclosure causes a computer to execute the above-described method.

[0010] A recording medium according to one aspect of the present disclosure records a program for causing a computer to execute the above-described method.

[0011] According to the present disclosure, it is possible to provide a body sound acquiring device, a body sound acquiring method, a program, and a recording medium that are capable of determining the S / N level of a body sound.

[0012] Graph showing the relationship between the frequency and sound pressure level of a body sound acquired by the body sound acquisition device of FIG. 1; Graph showing the relationship between the frequency and sound pressure level of a second signal acquired by a second band-limiting circuit from the body sound of FIG. 2; Graph showing the relationship between the frequency and sound pressure level of another example of a body sound acquired by the body sound acquisition device of FIG. 1; Graph showing the relationship between the frequency and sound pressure level of a second signal acquired by a second band-limiting circuit from the body sound of FIG. 4; Table showing an example of an S / N level; Flowchart for explaining the operation of the body sound acquisition device of FIG. 1; Schematic diagram showing a body sound sensor of the body sound acquisition device according to a first modification of the first embodiment; Block diagram showing a body sound acquisition device according to a second embodiment; Block diagram showing a body sound acquisition device according to a third embodiment; Block diagram showing a body sound acquisition device according to a fourth embodiment.

[0013] (Background to the present disclosure) In a device for acquiring biological sounds, such as an electronic stethoscope, a doctor may diagnose a specific disease based on the detection of a sound in a specific frequency band from the patient's breathing sound. At this time, the sound pressure in the specific frequency band may fall below the noise floor of the sensor, such as the electronic stethoscope. In this case, it may be difficult to distinguish between sounds specific to the disease and noise, which may lead to an incorrect diagnosis. The noise floor refers to the noise inherent in the device itself, such as the electronic stethoscope.

[0014] For example, the breathing sounds of patients with bronchial asthma include abnormal breathing sounds called wheezing. Whiezing is a relatively high-frequency sound that occurs when part of the airway is narrowed. In many patients, high-frequency sounds such as wheezing are often quieter than the volume of breathing sounds, and therefore are easily drowned out by the noise of the device itself.

[0015] Patent Document 1 discloses a respiratory sound analysis device that can decompose multiple sound types contained in respiratory sounds. However, in Patent Document 1, it is difficult to determine whether sufficient biological sounds for diagnosis have been acquired, making it difficult for doctors to make accurate diagnoses, and this hinders improvement in diagnostic efficiency.

[0016] Therefore, the present inventors have studied a body sound acquisition device, a body sound acquisition method, a program, and a recording medium that can determine the S / N level of body sounds, and have arrived at the following invention.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing, elements are shown exaggerated for ease of explanation.

[0018] First Embodiment [Overall Configuration] FIG. 1 is a block diagram schematically illustrating a body sound acquisition device according to a first embodiment of the present disclosure.

[0019] The body sound acquisition device 1 acquires a patient's body sounds and determines the signal-to-noise (SN) level of the acquired body sounds. Examples of the patient's body sounds include heart sounds, lung sounds, blood flow sounds, and bowel sounds. The SN level of the acquired body sounds indicates the noise state of the acquired body sounds and is a value obtained by comparing the signal and noise levels of the acquired body sounds. In this embodiment, an SN level equal to or greater than a predetermined value indicates that the body sounds have been acquired normally. An SN level less than the predetermined value indicates that the noise level is high and that the body sounds should be acquired again. For example, the noise level of the acquired body sounds may be high if the body sound sensor 10, such as a stethoscope, is not placed in an appropriate position on the patient or if the pressure applied to the body sound sensor 10 against the patient is too great or too small. Therefore, if the SN level is less than the predetermined value, it is necessary to adjust the auscultation position or pressure so that normal body sounds can be acquired. In this embodiment, it is possible to determine the S / N level that serves as a criterion for determining whether the acquired body sounds can be used for diagnosis or whether the body sounds should be acquired again by adjusting the auscultation position or pressure, etc.

[0020] 1, the body sound acquisition device 1 includes a body sound sensor 10, a first band limiting circuit 20, a second band limiting circuit 30, a calculation circuit 40, and a determination circuit 50. In this embodiment, the first band limiting circuit 20, the second band limiting circuit 30, the calculation circuit 40, and the determination circuit 50 can be realized by, for example, dedicated hardware circuits or hardware such as a microcontroller (MCU). The functions realized by these circuits may be realized by software or a combination of hardware and software.

[0021] The body sound sensor 10 is a device, such as an electronic stethoscope, that can acquire body sounds of a patient.

[0022] The first band limiting circuit 20 acquires a first signal by limiting the body sound acquired by the body sound sensor 10 to a predetermined frequency band. In this embodiment, the first band limiting circuit 20 includes a first AD converter 21 that converts the body sound into a digital signal, and a digital filter 22 that limits the digital signal converted by the first AD converter 21 to a predetermined frequency band.

[0023] The second band limiting circuit 30 limits the body sound acquired by the body sound sensor 10 to a predetermined frequency band and acquires a second signal that is amplified at a predetermined gain. In this embodiment, the second band limiting circuit 30 includes an analog filter 31, a first amplifier 32, and a second AD converter 33. The analog filter 31 acquires an analog signal that is obtained by limiting the body sound to a predetermined frequency band. The first amplifier 32 acquires an amplified signal that is obtained by amplifying the analog filter at a predetermined gain. The second AD converter 33 converts the amplified signal into a digital signal to acquire the second signal.

[0024] A first signal obtained by limiting the body sound to a predetermined frequency band is acquired by the first band limiting circuit 20, and a second signal obtained by limiting the body sound to a predetermined frequency band and amplifying it at a predetermined gain is acquired by the second band limiting circuit 30. The first signal and the second signal are different in that they are either amplified at a predetermined gain or not.

[0025] The calculation circuit 40 calculates characteristic values ​​including a value related to the sound pressure of the body sound. The characteristic values ​​calculated by the calculation circuit 40 include a first characteristic value of the first signal and a second characteristic value obtained by dividing the characteristic value of the second signal by a predetermined amplification factor.

[0026] The determination circuit 50 determines the S / N level, which indicates the state of noise in a predetermined frequency band of body sound, based on the first characteristic value and the second characteristic value. The S / N level indicates the level of noise in a predetermined frequency band of body sound. When the noise level is high, the S / N level becomes low, and sounds in the predetermined frequency band are buried in the noise, making it difficult to perform an accurate diagnosis. On the other hand, when the noise level is low, the S / N level becomes high, and sounds in the predetermined frequency band can be properly detected, making it easy to perform an accurate diagnosis.

[0027] The predetermined frequency band is a frequency band that includes sounds specific to a disease. In this embodiment, a case where the disease is childhood asthma or bronchial stenosis will be described as an example. The lung sounds of a patient with childhood asthma or bronchial stenosis include a relatively high-frequency sound component called a whistle due to the narrowing of the airway. Diagnosis of childhood asthma or bronchial stenosis is made based on the presence or absence of this whistle. The whistle is a sound in the frequency band of 0.8 kHz to 3.0 kHz that is included in lung sounds. Therefore, in this embodiment, the frequency band of 0.8 kHz to 3.0 kHz is set as the predetermined frequency band.

[0028] The characteristic value including the value related to the sound pressure of the body sound is, for example, the energy value of the sound pressure of the acquired body sound in a predetermined frequency band.

[0029] Fig. 2 is a graph showing the relationship between the frequency and sound pressure level of body sounds acquired by the body sound acquisition device of Fig. 1. In the example of Fig. 2, the predetermined frequency band is from frequency f1 to frequency f2. In this embodiment, as described above, frequency f1 is 0.8 kHz and frequency f2 is 3.0 kHz. In this embodiment, the characteristic value is the energy value of the sound pressure from frequency f1 to frequency f2 of the acquired body sounds, and is the value obtained by integrating the sound pressure levels of the body sounds from frequency f1 to frequency f2. That is, in this embodiment, the characteristic value is a value indicating the area of ​​region a1 in Fig. 2.

[0030] Next, the determination of the SN level in this embodiment will be described with reference to FIGS.

[0031] Fig. 2 is a graph showing the relationship between frequency and sound pressure level of an example of a body sound acquired by the body sound acquisition device of Fig. 1. Fig. 3 is a graph showing the relationship between frequency and sound pressure level of a second signal acquired by a second band limiting circuit from the body sound of Fig. 2. Fig. 4 is a graph showing the relationship between frequency and sound pressure level of another example of a body sound acquired by the body sound acquisition device of Fig. 1. Fig. 5 is a graph showing the relationship between frequency and sound pressure level of a second signal acquired by a second band limiting circuit from the body sound of Fig. 4. Note that Figs. 2 and 3 show graphs when body sounds are successfully acquired, and Figs. 4 and 5 show graphs when body sounds cannot be successfully acquired and the noise level is high.

[0032] The body sound acquired by the body sound sensor 10 is converted into an electric signal using, for example, a sound pressure conversion element (not shown) and amplified by an operational amplifier 60. Because the sound pressure level of the body sound acquired by the body sound sensor 10 is low, it is preferable to determine the signal-to-noise level using the electric signal amplified by the operational amplifier 60. Note that the sound pressure conversion element and the operational amplifier 60 are not essential components of the body sound acquisition device 1.

[0033] The electrical signal representing the body sound is input to the first band limiting circuit 20 and the second band limiting circuit 30 .

[0034] In the first band limiting circuit 20, the electrical signal is converted into a digital signal by the first AD converter 21. The body sound converted into a digital signal by the first AD converter 21 can be transmitted to, for example, an offline PC (not shown) and used for diagnosis. Next, the body sound converted into a digital signal by the first AD converter 21 is limited to a predetermined frequency band by the digital filter 22 to obtain a first signal.

[0035] The waveforms indicated by dashed lines in Figures 2 and 4 are waveforms showing the relationship between the frequency and sound pressure level of the body sound acquired by the body sound sensor 10. In the example of Figure 2, the sound pressure level of the acquired body sound is above the noise floor in all frequency bands, and the body sound has been acquired normally. On the other hand, in the example of Figure 4, there are frequency bands where the sound pressure level of the actual body sound is below the noise floor, and the body sound acquired by the body sound sensor 10 has a waveform of observation data shown by a thick dashed line. In the example of Figure 2, a diagnosis can be made based on the body sound acquired by the body sound sensor 10. However, in the example of Figure 4, there are many parts where the acquired body sound is below the noise floor, particularly in a predetermined frequency band from frequency f1 to frequency f2, making it difficult to make an accurate diagnosis based on the acquired body sound.

[0036] In the example of Fig. 2, the body sound amplified by the operational amplifier 60 has the waveform of the observation data shown by the thick dashed line. The first band-limiting circuit 20 acquires, as the first signal, the observation data from frequency f1 to frequency f2 of the observation data shown in Fig. 2. Similarly, the first band-limiting circuit 20 acquires, as the first signal, the observation data from frequency f1 to frequency f2 of the observation data shown in Fig. 4.

[0037] The second band-limiting circuit 30 first limits the body sound shown in FIGS. 2 and 4 to a predetermined frequency band using an analog filter 31. The filtered signal is amplified by a first amplifier 32 at a predetermined gain. The amplified signal is converted into a digital signal by a second AD converter 33 to obtain a second signal. The solid waveform shown in FIGS. 3 and 4 is the second signal. The predetermined gain is, for example, 100x, and preferably in the range of 5x to 500x. Alternatively, the predetermined gain can be arbitrarily selected from the range of 2x to 5000x, or 10x to 2000x. To reduce the risk of gain saturation and further improve signal clarity, the lower limit of the predetermined gain is preferably 2x and the upper limit is preferably 5000x. The predetermined gain can be calculated, for example, by measuring the input energy and output energy of the second band-limiting circuit 30 and calculating the ratio between the input energy and the output energy. For example, the input energy and the output energy can be the voltages of the signals input to and output from the second band-limiting circuit. Therefore, for example, a predetermined amplification factor can be calculated based on the ratio between the input voltage and the output voltage of the second band limiting circuit 30 .

[0038] In this embodiment, a case where the predetermined amplification factor is 100 will be described as an example. The signal amplified at the predetermined amplification factor is converted into a digital signal by the second AD converter 33, and the second signal is acquired. In the second band limiting circuit 30, the body sound is filtered in a predetermined frequency band and then amplified at a predetermined amplification factor, thereby making it possible to acquire a waveform of the body sound that does not include noise derived from the device.

[0039] Because the first band-limiting circuit 20 does not include an amplifier, the first signal acquired by the first band-limiting circuit 20 is obtained by filtering a predetermined frequency band of the body sound shown in Figures 2 and 4. On the other hand, the second band-limiting circuit 30 filters the predetermined frequency band and further amplifies it by 100 times, as shown in Figures 3 and 5, to acquire sound in the predetermined frequency band used for diagnosis at a sound pressure level higher than the noise floor. In other words, the first signal is a signal of body sound that includes noise from the device itself, and the second signal is a signal obtained by removing device noise from the body sound.

[0040] 2 and 3, the sound pressure level of the acquired body sound exceeds the noise floor. Therefore, the waveform acquired by the second band-limiting circuit 30 as the second signal shown in Fig. 3 and the waveform acquired by the first band-limiting circuit 20 as the first signal from the waveforms shown in Fig. 2 have substantially the same shape.

[0041] 4 and 5, the acquired body sounds, particularly those in a predetermined frequency band, are below the noise floor. Therefore, the waveform acquired by the second band-limiting circuit 30 as the second signal shown in Fig. 5 and the waveform acquired by the first band-limiting circuit 20 as the first signal among the waveforms shown in Fig. 4 have different shapes.

[0042] The calculation circuit 40 calculates the characteristic values ​​of the first signal and the second signal. In this embodiment, the characteristic values ​​of the first signal and the second signal are calculated as energy values ​​of the sound pressure levels of the first signal and the second signal, respectively.

[0043] The first characteristic value of the first signal can be calculated as an energy value of the sound pressure level of the waveform of the first signal. Specifically, the first characteristic value can be calculated by integrating the waveform in the range from frequency f1 to frequency f2 in Figures 2 and 4 to find the areas of regions a1 and a3.

[0044] For the second signal, an energy value of the sound pressure level of the waveform, which is the area of ​​region a2 in Figure 3 and region a4 in Figure 5, is calculated. The second signal is a signal obtained by amplifying a signal filtered to a predetermined frequency band with a predetermined amplification factor. Therefore, the second characteristic value is calculated by dividing the area of ​​region a2 in Figure 3 and region a5 in Figure 5 by the predetermined amplification factor. In this embodiment, the predetermined amplification factor is 100, so the value obtained by dividing the area of ​​region a2 and region a4 by 100 is calculated as the second characteristic value.

[0045] The determination circuit 50 determines an S / N level, which indicates the state of signals and noise in a predetermined frequency band of body sound, based on the first characteristic value and the second characteristic value. The S / N level is determined based on an S / N level index Cm, which is calculated using the first characteristic value EL and the second characteristic value EM. Specifically, the ratio of the second characteristic value EM to the first characteristic value EL is calculated as the S / N level index Cm, and the S / N level is calculated based on the S / N level index Cm. The S / N level index Cm is calculated using the formula Cm = EM / EL and is a value indicating the ratio of the second characteristic value EM to the first characteristic value EL.

[0046] As shown in Figures 2 and 3, when the acquired body sound is above the noise floor, the first characteristic value EL and the second characteristic value EM are approximately the same value. On the other hand, as shown in Figures 4 and 5, when the acquired body sound is below the noise floor, the first characteristic value EL contains noise components, but the second characteristic value EM has the noise components removed, so the value of the second characteristic value EM is smaller than the first characteristic value EL. The determination circuit 50 determines the SN level based on the ratio of the second characteristic value EM to the first characteristic value EL, i.e., the magnitude of the SN level index Cm.

[0047] FIG. 6 is a table showing examples of SNR levels. In the table of FIG. 6, SNR levels are classified into three stages according to the magnitude of the SNR level index Cm. When the SNR level index Cm is greater than 60 and less than or equal to 100, the ratio of the second characteristic value EM to the first characteristic value EL is relatively large, and it is assumed that the noise level contained in the first signal is not very high. Therefore, the determination circuit 50 determines the SNR level as "high" when the SNR level index Cm is greater than 60 and less than or equal to 100. When the SNR level index Cm is less than or equal to 40, it is assumed that the ratio of the second characteristic value EM to the first characteristic value EL is relatively small, and the noise level contained in the first characteristic value EL is high. Therefore, the determination circuit 50 determines the SNR level as "low" when the SNR level index Cm is less than or equal to 40. Furthermore, the determination circuit 50 determines the SNR level as "medium" when the SNR level index Cm is greater than 40 and less than or equal to 60.

[0048] For example, if the S / N level is determined to be "high," the user can determine that the body sounds have been acquired normally, and if the S / N level is determined to be "low," the user can determine that it is better to acquire the body sounds again. If the S / N level is determined to be "medium," the user can determine that it is better to adjust the auscultation position or pressure, although it does not go so far as to reacquire the body sounds. For example, when the S / N level is determined to be "medium," the user can determine that a more accurate diagnosis can be made by slightly increasing or decreasing the pressure, or by eliminating interference between the device and clothing at the contact position. Furthermore, by classifying the S / N level into three levels, the auscultation position or pressure can be optimized while acquiring body sounds and making an appropriate diagnosis.

[0049] [Operation] The operation of the body sound acquisition device 1 according to the first embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart for explaining the operation of the body sound acquisition device of Fig. 1.

[0050] First, in step S1, the patient's body sounds are acquired by the body sound sensor 10. The body sounds are acquired by a user bringing the body sound sensor 10, such as an electronic stethoscope, into contact with the patient, and the body sound sensor 10 detects body sounds such as the patient's heart sounds, lung sounds, blood flow sounds, or bowel sounds.

[0051] Next, in step S2, a first signal is acquired by the first band limiting circuit 20. The first signal can be acquired by converting the body sound acquired by the body sound sensor 10 into a digital signal by the first AD converter 21 and filtering the digital signal to a predetermined frequency band by the digital filter 22.

[0052] Next, in step S3, a second signal is acquired by the second band limiting circuit 30. The second signal can be acquired by filtering the body sound acquired by the body sound sensor 10 into a predetermined frequency band by the analog filter 31, amplifying the result at a predetermined gain by the first amplifier 32, and converting the result into a digital signal by the second AD converter 33.

[0053] Next, in step S4, the calculation circuit 40 acquires characteristic values. The characteristic values ​​include a first characteristic value EL of the first signal and a second characteristic value EM of the second signal. The first characteristic value EL is calculated as an energy value of the sound pressure level of the first signal. The second characteristic value EM is calculated as a value obtained by dividing the energy value of the sound pressure level of the second signal by a predetermined amplification factor.

[0054] Next, in step S5, the determination circuit 50 determines the SN level. The SN level is determined based on the SN level index Cm. The determination circuit 50 calculates the SN level index Cm based on the first characteristic value EL and the second characteristic value EM. The determination circuit 50 determines the SN level according to the value of the SN level index Cm. Once the SN level is determined, the operation of the body sound acquisition device 1 ends.

[0055] [Effects] According to the above-described embodiment, the following effects can be achieved.

[0056] The body sound acquisition device 1 includes a body sound sensor 10, a first band limiting circuit 20, a second band limiting circuit 30, a calculation circuit 40, and a determination circuit 50. The body sound sensor 10 acquires the body sound of a patient. The first band limiting circuit 20 acquires a first signal having a predetermined frequency band from the body sound. The second band limiting circuit 30 acquires a second signal having a predetermined frequency band from the body sound and amplified by a predetermined amplification factor. The calculation circuit 40 calculates a first characteristic value EL of the first signal and a second characteristic value EM by dividing the characteristic value of the second signal by the predetermined amplification factor, the first characteristic value EL including a value related to the sound pressure of the body sound. The determination circuit 50 determines an S / N level indicating the state of noise in the predetermined frequency band of the body sound based on the first characteristic value EL and the second characteristic value EM.

[0057] With this configuration, it is possible to provide a body sound acquisition device that can determine the S / N level of body sounds. By determining the S / N level, it is possible to understand the signal and noise conditions in the body sounds acquired by the body sound sensor 10, and it is possible to reliably acquire sounds in a predetermined frequency band and improve the efficiency of diagnosis.

[0058] The determination circuit 50 determines the SN level based on a comparison between the first characteristic value EL and the second characteristic value EM.

[0059] The determination circuit 50 calculates the ratio of the second characteristic value EM to the first characteristic value EL as an SN level index Cm, and determines the SN level based on the magnitude of the SN level index Cm.

[0060] With this configuration, the S / N level can be determined in multiple stages, allowing the user to appropriately acquire body sounds while adjusting the auscultation position or pressure.

[0061] The first band limiting circuit 20 includes a first AD converter 21 that converts the body sound into a digital signal and a digital filter 22 that limits the digital signal to a predetermined frequency band. The second band limiting circuit 30 includes an analog filter 31, a first amplifier 32, and a second AD converter 33. The analog filter 31 limits the body sound to a predetermined frequency band. The first amplifier 32 obtains an amplified signal by amplifying the analog signal by a predetermined gain. The second AD converter 33 converts the amplified signal into a digital signal to obtain a second signal.

[0062] With this configuration, it is possible to obtain the first signal and the second signal for calculating the first characteristic value EL and the second characteristic value EM.

[0063] The predetermined frequency band includes at least 0.8 kHz to 3.0 kHz.

[0064] With this configuration, the SNR level can be determined to detect the wheezing sound characteristic of childhood asthma, thereby improving the efficiency of diagnosing childhood asthma.

[0065] The predetermined amplification factor is 2 times or more and 5000 times or less.

[0066] With this configuration, the amplification factor can be changed according to the noise level, making it possible to more accurately determine the S / N level.

[0067] A method for acquiring a patient's biological sound and determining the state of the biological sound includes the steps of acquiring the biological sound, acquiring a first signal, acquiring a second signal, calculating a first characteristic value and a second characteristic value, and determining an S / N level.

[0068] With this configuration, it is possible to provide a method for determining the S / N level of body sounds.

[0069] The general and specific aspects of the present disclosure may be realized by a system, a method, a computer program and a computer-readable storage medium, and combinations thereof.

[0070] In the above-described embodiment, the SN level is classified into three stages for determination, but the present invention is not limited to this. The SN level may be classified into, for example, two stages or four or more stages for determination.

[0071] In the above-described embodiment, the first characteristic value EL and the second characteristic value EM are energy values ​​of the sound pressure level, but this is not limiting. The first characteristic value EL may be any one of the energy value of the sound pressure, the median value of the sound pressure, the median value of the sound pressure, the average value of the sound pressure, and the maximum value of the sound pressure of the first signal. The second characteristic value EM may be any one of the energy value of the sound pressure, the median value of the sound pressure, the median value of the sound pressure, the average value of the sound pressure, and the maximum value of the sound pressure of the second signal.

[0072] In the above-described embodiment, the first and second band-limiting circuits acquire signals limited to the same predetermined frequency band. However, the present invention is not limited to this. The first band-limiting circuit may acquire a first signal having a first frequency band from the body sound, and the second band-limiting circuit may acquire a second signal having a second frequency band narrower than the first frequency band from the body sound and amplified by a predetermined gain.

[0073] Furthermore, in the above-described embodiment, the predetermined frequency band is described as being 0.8 kHz to 3.0 kHz, but is not limited to this. The predetermined frequency band can be set to various ranges depending on the disease to be diagnosed. For example, if the target disease is interstitial pneumonia or pulmonary edema, the predetermined frequency band can be set to be 0.5 kHz to 1.0 kHz. In the case of interstitial pneumonia or pulmonary edema, sounds in the frequency band from 0.5 kHz to 1.0 kHz, known as crepitus, are observed in the patient's lung sounds. Furthermore, if the target disease is valvular heart disease or mitral valve regurgitation, the predetermined frequency band can be set to be 0.15 kHz to 0.9 kHz. In the case of valvular heart disease or mitral valve regurgitation, heart murmurs in the frequency band from 0.15 kHz to 0.9 kHz are observed in the patient's heart sounds.

[0074] [Modification] FIG. 8 is a schematic diagram showing a body sound sensor of a body sound acquisition device according to Modification 1 of Embodiment 1. As shown in FIG. 8, the body sound acquisition device may include a notification unit 61 that notifies the user of an S / N level. In the example of FIG. 8, the notification unit 61 is provided in the body sound sensor 10A. The notification unit 61 includes an LED 61a that notifies the user of the S / N level using a color and a display 61b that notifies the user of the S / N level using text information. Alternatively, the notification unit 61 may include either the LED 61a or the display 61b. The LED 61a notifies the user of the S / N level using a color corresponding to the S / N level determined by the determination circuit 50. For example, the S / N level determined by the determination circuit 50 can be notified by lighting the LED 61a in blue if the S / N level is "high," in yellow if the S / N level is "medium," and in red if the S / N level is "low." The display 61b can notify the user of the S / N level determined by the determination circuit 50 using text information. The user can check the display on the notification unit and adjust the auscultation position or pressure to perform auscultation at a high S / N level. The notification unit 61 may also be a speaker, and may notify the determination circuit 50 of the determined S / N level by voice.

[0075] (Embodiment 2) A body sound acquisition device according to embodiment 2 of the present disclosure will be described. In embodiment 2, differences from embodiment 1 will be mainly described. In embodiment 2, components that are the same as or equivalent to those in embodiment 1 will be described using the same reference numerals. Furthermore, in embodiment 2, descriptions that overlap with embodiment 1 will be omitted.

[0076] Fig. 9 is a block diagram schematically illustrating a body sound acquisition device 2 according to the second embodiment. As shown in Fig. 9, the second embodiment differs from the first embodiment in the configurations of the first band limiting circuit 120 and the second band limiting circuit 130. The other configurations of the body sound acquisition device 2 are the same as those of the first embodiment, and therefore, description thereof will be omitted.

[0077] In the present embodiment, the first band limiting circuit 120 includes a first analog filter 123 and a third AD converter 121. The first analog filter 123 acquires an analog signal by limiting the body sound acquired by the body sound sensor 10 to a predetermined frequency band. The third AD converter 121 acquires a first signal by converting the analog signal filtered to the predetermined frequency band into a digital signal. In the first embodiment, the first band limiting circuit acquires the first signal by converting it to a digital signal and then limiting it to a predetermined frequency band. In the present embodiment, the first band limiting circuit 120 acquires the first signal by filtering it to a predetermined frequency band and then converting it into a digital signal.

[0078] In this embodiment, the second band limiting circuit 130 includes a second analog filter 131, a second amplifier 132, and a fourth AD converter 133. The second analog filter 131 obtains an analog signal by limiting the frequency of the body sound obtained by the body sound sensor 10 to a predetermined frequency. The second amplifier 132 obtains an amplified signal by amplifying the analog signal at a predetermined gain. The fourth AD converter 133 converts the amplified signal into a digital signal to obtain a second signal. As in the first embodiment, the second band limiting circuit 130 obtains the second signal by filtering the body sound to a predetermined frequency band, amplifying it at a predetermined frequency, and then converting it into a digital signal.

[0079] In this embodiment, the first analog filter 123 and the second analog filter 131 are configured as a common analog filter. Therefore, in this embodiment, the first band limiting circuit 120 and the second band limiting circuit 130 filter the body sound acquired by the body sound sensor 10 into a predetermined frequency band using the common analog filters 123, 131. The first band limiting circuit 120 converts the filtered signal into a digital signal. The second band limiting circuit 130 amplifies the filtered signal and then converts it into a digital signal.

[0080] This configuration can further reduce the calculation cost, and therefore the S / N level can be determined more quickly while the body sound acquisition device 2 is in use.

[0081] Furthermore, since the calculation cost can be reduced, the hardware can be simplified and the manufacturing cost can be reduced.

[0082] (Embodiment 3) A body sound acquisition device according to embodiment 3 of the present disclosure will be described. In embodiment 3, differences from embodiment 1 will be mainly described. In embodiment 3, components that are the same as or equivalent to those in embodiment 1 will be described using the same reference numerals. Furthermore, in embodiment 3, descriptions that overlap with embodiment 1 will be omitted.

[0083] Fig. 10 is a block diagram schematically illustrating a body sound acquisition device 3 according to the third embodiment. As shown in Fig. 10, the third embodiment differs from the first embodiment in that the first band limiting circuit 220 includes a third band limiting circuit 320 and a fourth band limiting circuit 420, and the second band limiting circuit 230 includes a fifth band limiting circuit 330 and a sixth band limiting circuit 430. The other configurations are the same as those of the first embodiment, and therefore will not be described again.

[0084] In this embodiment, the predetermined frequency band includes a first frequency band and a second frequency band. The first frequency band includes, for example, frequencies from 0.8 kHz to 3.0 kHz, and is a frequency band including sounds characteristic of childhood asthma or bronchial stenosis. The second frequency band includes, for example, frequencies from 0.5 kHz to 1.0 kHz, and is a frequency band including sounds characteristic of interstitial pneumonia or pulmonary edema.

[0085] The third band limiting circuit 320 acquires a third signal limited to a first frequency band. In this embodiment, the third band limiting circuit 320 includes a digital filter 322, and the digital filter 322 of the third band limiting circuit 320 limits the signal digitally converted by the AD converter 221 to the first frequency band. The fourth band limiting circuit 420 acquires a fourth signal limited to a second frequency band. In this embodiment, the fourth band limiting circuit 420 includes a digital filter 422, and the digital filter 422 of the fourth band limiting circuit 420 limits the signal digitally converted by the AD converter 221 to the second frequency band. In this embodiment, the third band limiting circuit 320 and the fourth band limiting circuit 420 share the same AD converter 221.

[0086] The fifth band limiting circuit 330 obtains a fifth signal by amplifying the signal limited to the first frequency band at a predetermined gain. In this embodiment, the fifth band limiting circuit 330 includes an analog filter 331, an amplifier 332, and an AD converter 333. The sixth band limiting circuit 430 obtains a sixth signal by amplifying the signal limited to the second frequency band at a predetermined gain. In this embodiment, the sixth band limiting circuit 430 includes an analog filter 431, an amplifier 432, and an AD converter 433.

[0087] As described above, the third band limiting circuit 320 and the fifth band limiting circuit 330 acquire signals from the body sound that have been limited to a first frequency band, and the fourth band limiting circuit 420 and the sixth band limiting circuit 430 acquire signals from the body sound that have been limited to a second frequency band. The determination circuit 50 determines the S / N level based on the first characteristic value of the third signal and the second characteristic value of the fifth signal calculated by the calculation circuit 40. Similarly, the determination circuit 50 determines the S / N level based on the first characteristic value of the fourth signal and the second characteristic value of the sixth signal calculated by the calculation circuit 40.

[0088] The S / N level determined based on the first characteristic value of the third signal and the second characteristic value of the fifth signal can indicate whether the acquired body sounds are in a state where a diagnosis using sounds in a first frequency band, such as childhood asthma or bronchial stenosis, can be accurately performed. Similarly, the S / N level determined based on the first characteristic value of the fourth signal and the second characteristic value of the sixth signal can indicate whether a diagnosis using sounds in a second frequency band, such as interstitial pneumonia or pulmonary edema, can be accurately performed.

[0089] By assigning different frequency bands to the first band limiting circuit 220 and the second band limiting circuit 230, the S / N levels for sounds in frequency bands specific to multiple diseases can be determined, making it possible to grasp the S / N levels for each of multiple diseases and further improving the efficiency of diagnosis.

[0090] (Fourth embodiment) A body sound acquisition device according to a fourth embodiment of the present disclosure will be described. In the fourth embodiment, differences from the first embodiment will be mainly described. In the fourth embodiment, the same or equivalent configurations as those in the first embodiment will be denoted by the same reference numerals. Furthermore, in the fourth embodiment, descriptions that overlap with those in the first embodiment will be omitted.

[0091] Fig. 11 is a block diagram showing a schematic configuration of a body sound acquisition device 4 according to the fourth embodiment. As shown in Fig. 11, the fourth embodiment differs from the first embodiment in that the body sound acquisition device 4 includes a communication circuit 70, and the communication circuit 70 acquires the body sounds acquired by the body sound sensor 10 via a network. The other configurations are the same as those of the first embodiment, and therefore will not be described again.

[0092] The communication circuit 70 is a circuit that can transmit and receive data according to, for example, a mobile communication standard such as 5G or 4G, a short-range wireless communication standard such as Bluetooth (registered trademark), Wi-Fi (registered trademark), or ZigBee (registered trademark), or a wired communication standard such as Ethernet (registered trademark). In this embodiment, the communication circuit 70 receives the body sound acquired by the body sound sensor 10 via a network through wireless or wired communication. The body sound received by the communication circuit 70 is input to the first band limiting circuit 20 and the second band limiting circuit 30.

[0093] By acquiring body sounds via a network, the body sound acquisition device 4 can be used for remote diagnosis and the like.

[0094] (Summary of embodiment) (1) A body sound acquisition device according to one aspect of the present disclosure includes a body sound sensor that acquires the body sound of a patient, a first band-limiting circuit that acquires a first signal having a predetermined frequency band from the body sound, a second band-limiting circuit that acquires a second signal having the predetermined frequency band from the body sound and amplified by a predetermined amplification factor, a calculation circuit that calculates a second characteristic value obtained by dividing a first characteristic value of the first signal and a characteristic value of the second signal, each of which includes a value related to the sound pressure of the body sound, by the predetermined amplification factor, and a determination circuit that determines an S / N level that indicates the state of the signal and noise in the predetermined frequency band of the body sound based on the first characteristic value and the second characteristic value.

[0095] (2) In the body sound acquisition device of (1), the first band-limiting circuit may acquire a first signal having a first frequency band from the body sound, and the second band-limiting circuit may acquire a second signal having a second predetermined frequency band from the body sound that is narrower than the first predetermined frequency band and amplified by a predetermined amplification factor.

[0096] (3) In the body sound acquisition device of (1) or (2), the determination circuit may determine the S / N level based on a comparison between the first characteristic value and the second characteristic value.

[0097] (4) In any one of the biological sound acquisition devices (1) to (3), the judgment circuit may calculate the ratio of the second characteristic value to the first characteristic value as an SN level index, and judge the SN level based on the magnitude of the SN level index.

[0098] (5) In any one of the biological sound acquisition devices (1) to (4), the first band-limiting circuit may include a first AD converter that converts the biological sound into a digital signal and a digital filter that limits the digital signal to a predetermined frequency band, and the second band-limiting circuit may include an analog filter that acquires an analog signal obtained by limiting the biological sound to the predetermined frequency band, a first amplifier that acquires an amplified signal obtained by amplifying the analog signal at a predetermined amplification factor, and a second AD converter that converts the amplified signal into a digital signal to acquire a second signal.

[0099] (6) In the body sound acquisition device of any one of (1) to (4), the first band-limiting circuit includes a first analog filter that acquires an analog signal in which the body sound is limited to a predetermined frequency band, and a third AD converter that converts the analog signal into a digital signal to acquire the first signal; the second band-limiting circuit includes a second analog filter that acquires an analog signal in which the body sound is limited to the predetermined frequency band, a second amplifier that acquires an amplified signal in which the analog signal is amplified by a predetermined amplification factor, and a fourth AD converter that converts the amplified signal into a digital signal to acquire the second signal; and the first analog filter and the second analog filter may be configured by a common analog filter.

[0100] (7) In the body sound acquisition device according to any one of (1) to (6), the predetermined frequency band may be a frequency band including at least 0.8 kHz to 3.0 kHz.

[0101] (8) In the body sound acquisition device according to any one of (1) to (7), the predetermined amplification factor may be 2 times or more and 5000 times or less.

[0102] (9) In the biological sound acquisition device of (1) to (8), the predetermined frequency band may include a first frequency band and a second frequency band, the first band limiting circuit may include a third band limiting circuit that acquires a third signal having the first frequency band and a fourth band limiting circuit that acquires a fourth signal having the second frequency band, and the second band limiting circuit may include a fifth band limiting circuit that acquires a fifth signal obtained by amplifying the signal having the first frequency band at a predetermined amplification factor, and a sixth band limiting circuit that acquires a sixth signal obtained by amplifying the signal having the second frequency band at a predetermined amplification factor.

[0103] (10) In any one of the biological sound acquisition devices (1) to (9), the first characteristic value may be any one of the energy value of the sound pressure in the first signal, the median processed value of the sound pressure, the median value of the sound pressure, the average value of the sound pressure, or the maximum value of the sound pressure, and the second characteristic value may be any one of the energy value of the sound pressure in the second signal, the median processed value of the sound pressure, the median value of the sound pressure, the average value of the sound pressure, or the maximum value of the sound pressure.

[0104] (11) The body sound acquisition device according to any one of (1) to (10) may further include a notification unit that notifies the user of an SN level.

[0105] (12) In the body sound acquisition device of (11), the notification unit may include at least one of a display, an LED, or a speaker.

[0106] (13) A body sound acquisition device according to another aspect of the present disclosure may include a communication circuit that acquires a patient's body sound via a network; a first band-limiting circuit that acquires a first signal having a predetermined frequency band from the body sound; a second band-limiting circuit that acquires a second signal having the predetermined frequency band from the body sound and amplified by a predetermined amplification factor; a calculation circuit that calculates a second characteristic value obtained by dividing a first characteristic value of the first signal and a characteristic value of the second signal, each of which includes a value related to the sound pressure of the body sound, by the predetermined amplification factor; and a determination circuit that determines an S / N level that indicates the state of signal and noise in the predetermined frequency band of the body sound based on the first characteristic value and the second characteristic value.

[0107] (14) A method according to one aspect of the present disclosure is a method for acquiring a patient's body sound and determining the state of the body sound, the method including the steps of acquiring the patient's body sound, acquiring a first signal by limiting the acquired body sound to a predetermined frequency band, acquiring a second signal by limiting the acquired body sound to the predetermined frequency band and amplified by a predetermined amplification factor, calculating a second characteristic value by dividing a first characteristic value of the first signal and a characteristic value of the second signal, the first characteristic value including a value related to the sound pressure of the body sound, by the predetermined amplification factor, and determining an S / N level indicating the state of signal and noise in the predetermined frequency band of the body sound based on the first characteristic value and the second characteristic value.

[0108] (15) A program according to one aspect of the present disclosure causes a computer to execute the method of (14).

[0109] (16) A computer-readable recording medium according to one aspect of the present disclosure records a program for causing a computer to execute the method of (14).

[0110] The present disclosure is applicable to a device, a method, a program, and a recording medium for acquiring body sounds of a patient.

[0111] 1 to 4 Body sound acquisition device 10, 10A Body sound sensor 20, 120, 220 First band limiting circuit 21 First AD converter 22 Digital filter 30, 130, 230 Second band limiting circuit 31 Analog filter 32 First amplifier 33 Second AD converter 40 Calculation circuit 50 Determination circuit 61 Notification unit 61a LED 61b Display 70 Communication circuit 320 Third band limiting circuit 330 Fifth band limiting circuit 420 Fourth band limiting circuit 430 Sixth band limiting circuit

Claims

1. A biological sound acquisition device comprising: a biological sound sensor for acquiring a patient's biological sound; a first band-limiting circuit for acquiring a first signal having a predetermined frequency band among the biological sounds; a second band-limiting circuit for acquiring a second signal having the predetermined frequency band among the biological sounds and amplified at a predetermined amplification rate; a calculation circuit for calculating a first characteristic value of the first signal including a value related to the sound pressure of the biological sound and a second characteristic value obtained by dividing the characteristic value of the second signal by the predetermined amplification rate; and a determination circuit for determining an SN level indicating the state of a signal and noise in the predetermined frequency band of the biological sound based on the first characteristic value and the second characteristic value.

2. The biological sound acquisition device according to claim 1, wherein the first band-limiting circuit acquires a first signal having a first predetermined frequency band among the biological sounds, and the second band-limiting circuit acquires a second signal having a second predetermined frequency band narrower than the first predetermined frequency band among the biological sounds and amplified at a predetermined amplification rate.

3. The biological sound acquisition device according to claim 1 or 2, wherein the determination circuit determines the SN level based on a comparison between the first characteristic value and the second characteristic value.

4. The biological sound acquisition device according to any one of claims 1 to 3, wherein the determination circuit calculates a ratio of the second characteristic value to the first characteristic value as an SN level index, and determines the SN level based on the magnitude of the SN level index.

5. The biological sound acquisition device according to any one of claims 1 to 4, wherein the first band-limiting circuit includes a first AD converter for converting the biological sound into a digital signal and a digital filter for limiting the digital signal to the predetermined frequency band, and the second band-limiting circuit includes an analog filter for acquiring an analog signal obtained by limiting the biological sound to the predetermined frequency band, a first amplifier for acquiring an amplified signal obtained by amplifying the analog signal at the predetermined amplification rate, and a second AD converter for converting the amplified signal into a digital signal to acquire a second signal.

6. The first band-limiting circuit includes a first analog filter that acquires an analog signal obtained by limiting the biological sound to the predetermined frequency band, and a third AD converter that converts the analog signal into a digital signal to acquire the first signal. The second band-limiting circuit includes a second analog filter that acquires an analog signal obtained by limiting the biological sound to the predetermined frequency band, a second amplifier that acquires an amplified signal obtained by amplifying the analog signal at the predetermined amplification factor, and a fourth AD converter that converts the amplified signal into a digital signal to acquire a second signal. The first analog filter and the second analog filter are constituted by a common analog filter. The biological sound acquisition device according to any one of claims 1 to 4.

7. The predetermined frequency band is a frequency band including at least 0.8 kHz or more and 3.0 kHz or less. The biological sound acquisition device according to any one of claims 1 to 6.

8. The predetermined amplification factor is 2 times or more and 5000 times or less. The biological sound acquisition device according to any one of claims 1 to 7.

9. The predetermined frequency band includes a first frequency band and a second frequency band. The first band-limiting circuit includes a third band-limiting circuit that acquires a third signal having the first frequency band, and a fourth band-limiting circuit that acquires a fourth signal having the second frequency band. The second band-limiting circuit includes a fifth band-limiting circuit that acquires a fifth signal obtained by amplifying a signal having the first frequency band at the predetermined amplification factor, and a sixth band-limiting circuit that acquires a sixth signal obtained by amplifying a signal having the second frequency band at the predetermined amplification factor. The biological sound acquisition device according to any one of claims 1 to 8.

10. The first characteristic value is any one of the energy value of the sound pressure, the median processed value of the sound pressure, the median value of the sound pressure, the average value of the sound pressure, or the maximum value of the sound pressure in the first signal. The second characteristic value is any one of the energy value of the sound pressure, the median processed value of the sound pressure, the median value of the sound pressure, the average value of the sound pressure, or the maximum value of the sound pressure in the second signal. The biological sound acquisition device according to any one of claims 1 to 9.

11. Further, it includes a notification unit that notifies the SN level. The biological sound acquisition device according to any one of claims 1 to 10.

12. The notification unit includes at least one of a display, an LED, or a speaker, and the biological sound acquisition device according to claim 11.

13. A biological sound acquisition device comprising: a communication circuit that acquires a patient's biological sound via a network; a first band-limiting circuit that acquires a first signal having a predetermined frequency band among the biological sounds; a second band-limiting circuit that acquires a second signal having the predetermined frequency band among the biological sounds and amplified at a predetermined amplification rate; a calculation circuit that calculates a first characteristic value of the first signal including a value related to the sound pressure of the biological sound and a second characteristic value obtained by dividing the characteristic value of the second signal by the predetermined amplification rate; and a determination circuit that determines an SN level indicating a state of a signal and noise in the predetermined frequency band of the biological sound based on the first characteristic value and the second characteristic value.

14. A method for acquiring a patient's biological sound and determining a state of the biological sound, the method including: a step of acquiring the patient's biological sound; a step of acquiring a first signal having a predetermined frequency band among the acquired biological sounds; a step of acquiring a second signal having the predetermined frequency band among the acquired biological sounds and amplified at a predetermined amplification rate; a step of calculating a first characteristic value of the first signal including a value related to the sound pressure of the biological sound and a second characteristic value obtained by dividing the characteristic value of the second signal by the predetermined amplification rate; and a step of determining an SN level indicating a state of a signal and noise in the predetermined frequency band of the biological sound based on the first characteristic value and the second characteristic value.

15. A program for causing a computer to execute the method according to claim 14.

16. A computer-readable recording medium having recorded thereon a program for causing a computer to execute the method according to claim 14.

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