JP2022101029A - Biological sound signal processing device and biological sound signal processing method - Google Patents

Abstract

To provide a biological sound signal processing device and a biological sound signal processing method capable of reducing a biological sound as noise, and collecting a small biological sound as an object of auscultation.SOLUTION: Detection parts 1A and 1B collect auscultation signals containing a cardiac sound as noise unnecessary for the auscultation at the mutually separated positions. The auscultation sound signals are compared at a calculation part 2, and a signal resultant from a biological sound which is noise at a position where auscultation is to be executed is generated as a virtual noise signal. The virtual noise signal is subtracted from the auscultation signal at the position where auscultation is to be executed at a third auscultation signal calculation part 22 so that the auscultation signal that does not contain noise or in which noise is substantially reduced is acquired.SELECTED DRAWING: Figure 5

Description

The present invention relates to a signal processing device and a signal processing method for biological sounds including noise composed of biological sounds.

The electronic stethoscope has a configuration in which biological sound is collected by a chest piece, the biological sound collected by a microphone or the like is converted into a biological sound signal, signal processing such as amplification or filtering is performed by a signal processing circuit, and the sound is output to an earpiece or the like. It has become. The signal processing for noise reduction generally performed here has been performed to reduce noise and environmental noise generated at the start and end of the examination (Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 10-240033 Japanese Unexamined Patent Publication No. 2016-67857

By the way, even if noise other than biological sound can be reduced, it is not always possible to perform a desired auscultation. For example, when auscultating the body of a person to be auscultated, the heart sounds that are constantly generated in the body of the auscultated person are very large, and when a small biological sound other than the heart sounds is to be auscultated, the heart sounds that are the biological sounds become noise. It ends up. In view of such an actual situation, it is an object of the present invention to provide a biological sound signal processing device and a biological sound signal processing method capable of reducing biological sounds that become noise and collecting small biological sounds to be auscultated. do.

In order to achieve the above object, the biological sound signal processing device according to claim 1 of the present application collects a first hearing signal including a biological sound that becomes noise from the first hearing unit of the listener, and the first one. A detection unit that collects a second hearing signal including a biological sound that becomes noise from a second hearing unit away from the hearing unit, and a virtual comparison between the first hearing signal and the second hearing signal. It is provided with a calculation unit that generates a noise signal and calculates a third hearing signal that is a hearing signal in the first hearing unit from the difference between the first hearing signal and the virtual noise signal. It is a feature.

The biological sound signal processing method according to claim 2 of the present application includes a step of collecting a first auscultation signal including auscultatory sound that becomes noise from the first auscultation unit of the auscultated person, and the first auscultated person. The step of collecting the second auscultation signal including the biological sound that becomes noise from the second auscultation unit away from the auscultation unit, the first auscultation signal and the second auscultation signal are compared, and the first auscultation signal is compared. From the step of generating the virtual noise signal included in the auscultation signal 1 and the difference between the first auscultation signal and the virtual noise signal, a third auscultation signal to be the auscultation signal in the first auscultation unit is calculated. It is characterized by including steps to be performed.

The biological sound signal processing method according to claim 3 of the present application is the biological sound signal processing method according to claim 2, wherein the step of collecting the first hearing signal and the second hearing signal is the biological sound that becomes noise. It is characterized in that it is a step of collecting a hearing signal including a heartbeat.

According to the present invention, auscultation signals at distant positions are collected and compared to generate a virtual noise signal in a desired auscultation unit, and a desired auscultation signal is calculated from the difference between the collected auscultation signal and the virtual noise signal. Therefore, it is possible to auscultate a biological sound having a low signal level without being affected by noise caused by the biological sound. The biological sound signal processing method of the present invention is particularly effective when a heart sound having a large signal level becomes noise.

It is explanatory drawing of the Embodiment of this invention. It is explanatory drawing of the Embodiment of this invention. It is explanatory drawing of the Embodiment of this invention. It is explanatory drawing of the Embodiment of this invention. It is explanatory drawing of the biological sound signal processing apparatus of 1st Embodiment of this invention. It is explanatory drawing of the biological sound signal processing apparatus of the 2nd Embodiment of this invention.

The biological sound signal processing apparatus and the biological sound signal processing method of the present invention first collect auscultation signals including the same biological sound, which is unnecessary noise for auscultation at positions separated from each other by the detection unit. This auscultation sound signal is compared by the calculation unit, and a signal caused by a biological sound that becomes noise at the position to be auscultated is generated as a virtual noise signal. By subtracting this virtual noise signal from the auscultation signal at the position to be auscultated, it is possible to obtain an auscultation signal that does not contain noise or has significantly reduced noise.

For example, an embodiment of the present invention will be described by taking as an example the case of performing auscultation of the abdomen (auscultation unit A: corresponding to the first auscultation unit) shown in FIG.

The biological sound signal processing device of the present invention can be configured by adding it to a signal processing device of a general electronic stethoscope, and the signal processing method of the present invention can be realized. When auscultation of the auscultation unit A is performed using a general electronic stethoscope, intestinal sounds including heart sounds are collected. At this time, the intestinal sound is small and the heart sound is large. Therefore, when auscultating the intestinal sound, the heart sound becomes noise.

Therefore, the auscultation signal of the auscultation unit A is collected and the auscultation signal is collected by the auscultation unit B (corresponding to the second auscultation unit). In this case, the heart sound becomes noise, so the auscultation unit B is set at a position close to the heart in order to measure the heart sound. Hereinafter, the signal collected by the auscultation unit A will be referred to as a first auscultation signal, and the signal collected by the auscultation unit B will be referred to as a second auscultation signal.

The first auscultation signal is a signal in which the heart sound generated in the heart is attenuated or modulated while propagating in the body of the auscultated person, and the intestinal sound is added to the signal. On the other hand, the second auscultation signal is a signal in which the heart sound generated in the heart propagates in the body of the auscultated person and is hardly attenuated. In the body of the auscultated person, biological sounds such as breath sounds other than heart sounds are generated and become noise. On the other hand, since heart sounds are the loudest noises in auscultation of the body, noises caused by biological sounds such as heart sounds and breath sounds will be described as "heart sounds".

FIG. 2 shows an example of the first auscultation signal (a) and the second auscultation signal (b). As shown in FIG. 2, it can be seen that periodic signals are collected in both the first auscultation signal (a) and the second auscultation signal (b). This is the signal (noise) caused by the heartbeat. Further, when the first auscultation signal (a) and the second auscultation signal (b) are compared with respect to this periodic signal, the periodic signal included in the second auscultation signal (b) is delayed and attenuated. It can also be seen that the signal is modulated and collected as the first auscultation signal (a).

Next, this periodic signal is compared. For example, FIG. 3 shows the Fourier transform by extracting the first auscultation signal including the peak signal of the periodic signal and the second auscultation signal for a predetermined fixed time (time during which one heartbeat can be measured). The result is shown. The Fourier transform result of the first auscultation signal is shown by a solid line, and the Fourier transform result of the second auscultation signal is shown by a broken line.

In the example shown in FIG. 3, in the signal near 15 Hz to 50 Hz, the level of the second auscultation signal is higher than the level of the first auscultation signal. That is, it can be seen that the attenuation is large. On the other hand, in the signal near 1 Hz to 5 Hz and the signal near 8 Hz, the level of the first auscultation signal is higher than the level of the second auscultation signal. That is, it can be seen that a signal that is not included in the second auscultation signal is included.

Therefore, the noise signal included in the first auscultation signal is subtracted. Here, the noise signal to be subtracted is referred to as a virtual noise signal. In the example shown in FIG. 3, when the first auscultation signal and the second auscultation signal are compared, it can be seen that a desired auscultation signal can be obtained even if the second auscultation signal is used as a virtual noise signal as it is. Therefore, the second auscultation signal is used as it is as a virtual noise signal.

By subtracting the virtual noise signal (second auscultation signal) from the first auscultation signal, a signal in the vicinity of 1 Hz to 5 Hz and a signal in the vicinity of 8 Hz are obtained. The inverse Fourier transform of this signal yields a desired third auscultation signal with noise removed. In addition, in the calculation of the third auscultation signal, filtering, gain adjustment, and the like performed in a general electronic stethoscope are naturally performed.

Further, the method of obtaining the virtual noise signal can be variously changed. For example, when the first auscultation signal and the second auscultation signal shown in FIG. 3 are compared, it can be seen that the signal of the second auscultation signal in the vicinity of 15 Hz to 50 Hz is greatly attenuated. Using this attenuation rate, the entire second auscultation signal can be attenuated to obtain a virtual noise signal, which can be subtracted from the first auscultation signal to obtain a third auscultation signal.

FIG. 4 shows an example in which the second auscultation signal is attenuated over the entire frequency band shown in the figure. The attenuation factor is an example in which the second auscultation signal in the vicinity of 15 Hz to 50 Hz is attenuated so as to match the level of the first auscultation signal.

In this case as well, by subtracting the virtual noise signal (attenuated second hearing signal) from the first hearing signal, a signal near 1 Hz to 15 Hz is obtained, and this signal is inverse Fourier transformed to obtain the required signal. By adding the treatment, a desired third hearing signal can be obtained.

Further, although not shown, as another method for obtaining a virtual noise signal, it is possible to change the attenuation rate for each frequency band when the second auscultation signal is attenuated. A signal processing such as extracting only a signal in a predetermined frequency band or excluding a signal in an unnecessary frequency band, or a method in which the above signal processing is combined may be used.

The generation of the virtual noise signal may be appropriately changed so that the third auscultation signal required for auscultation includes the biological sound to be auscultated.

As described above, since the virtual noise signal is generated by the biological sound processing method of the present invention, it is preferable to collect the noise caused by the same biological sound as the first auscultation signal and the second auscultation signal. Therefore, it is desirable that the detection unit of the biological sound signal processing device of the present invention includes a plurality of sound collecting units so that the first auscultation unit and the second auscultation unit at positions separated from each other simultaneously obtain the auscultation signal. On the other hand, for biological signals with variations such as heart sounds, it may not always be necessary to compare the same signals. For example, the first auscultation unit collects the first auscultation signal for a predetermined time, and then the second auscultation unit collects the second auscultation signal for a predetermined time. It is also possible to generate a virtual noise signal. Hereinafter, examples of the biological sound processing apparatus for realizing the biological sound signal processing method in the present invention will be described in detail.

As a first embodiment of the present invention, a biological sound signal processing device capable of simultaneously collecting a first auscultation signal and a second auscultation signal will be described. FIG. 5 is an explanatory diagram of the biological sound signal processing device of this embodiment. Two chest pieces of a general electronic stethoscope are provided, one chest piece is a detection unit 1A, and the other chest piece is a detection unit 1B. Each of the detection units 1A and 1B is provided with a microphone, and converts the biological sound into a biological sound signal. Here, when the auscultation unit A shown in FIG. 1 is auscultated using the detection unit 1A and the auscultation unit B is auscultated using the detection unit 1B, the first auscultation signal from the detection unit 1A is transmitted from the detection unit 1B. The second auscultation signal is output respectively.

The calculation unit 2 can be configured in a signal processing unit of a general electronic stethoscope. The biological signal collected by the detection unit 1A in the calculation unit 2 is input to the comparison unit 21 as a first auscultation signal. Similarly, the biological sound collected by the detection unit 1B is input to the comparison unit 21 as a second auscultation signal. The comparison unit 21 compares the input first auscultation signal and the second auscultation signal, generates a virtual noise signal according to the biological sound signal processing method described above, and outputs the virtual noise signal to the third auscultation signal calculation unit 22. ..

The third auscultation signal calculation unit 22 subtracts the virtual noise signal from the first auscultation signal input from the detection unit 1A, and calculates the difference as the third auscultation signal. Since it is desirable that the first auscultation signal is a signal used to generate a virtual noise signal, the first auscultation signal may be input from the comparison unit 21. The third auscultation signal calculated by the third auscultation signal calculation unit 22 is subjected to signal processing in a normal electronic stethoscope and output to an output terminal 3 connected to an earpiece or the like so that the listener can recognize it. Will be. The signal processing performed by the calculation unit 2 can be processed by the semiconductor integrated circuit.

Next, as a second embodiment, a biological sound signal processing device capable of collecting a first auscultation signal and a second auscultation signal by a single detection unit will be described. FIG. 6 is an explanatory diagram of the biological sound signal processing device of this embodiment. Since the chest piece is composed of only one in this embodiment, it can be configured with a general electronic stethoscope. One chest piece is used as the detection unit 1C. The auscultation unit A shown in FIG. 1 is auscultated for a certain period of time, and the auscultation unit B is auscultated for a certain period of time.

The first auscultation signal, which is the auscultation result of the auscultation unit A collected by the detection unit 1C, is output to the calculation unit 2. Further, the second auscultation signal, which is the auscultation result of the auscultation unit B collected by the detection unit 1C, is also output to the calculation unit 2.

In the calculation unit 2, the first auscultation signal and the second auscultation signal are input to the comparison unit 21. The comparison unit 21 includes a storage unit 23, and sequentially stores the first auscultation signal and the second auscultation signal. After the first hearing signal and the second hearing signal are input, the comparison unit 21 reads out the first hearing signal and the second hearing signal from the storage unit 23, compares them, and processes the biological sound signal described above. A virtual noise signal is generated according to the method and output to the third hearing signal calculation unit 22.

The third auscultation signal calculation unit 22 reads the first auscultation signal stored in the storage unit 23, subtracts the virtual noise signal from the first auscultation signal, and calculates the difference as the third auscultation signal. do. This third auscultation signal is subjected to signal processing in a normal electronic stethoscope and is output to an output terminal 3 connected to an earpiece or the like so that the auscultator can recognize it. The signal processing performed by the calculation unit 2 can be processed by the semiconductor integrated circuit.

As described above, the biological sound signal processing device that realizes the biological sound signal processing method of the present invention can be easily configured by adding a detection unit to a normal electronic stethoscope or by using a normal electronic stethoscope. ..

Needless to say, the biological sound processing method and the biological sound processing apparatus of the present invention are not limited to the above examples. For example, the heart sound has been described as an example of the noise of the biological sound, but the biological sound that becomes the noise is not limited to this, and the auscultation units A and B may be appropriately changed in order to collect the desired biological sound.

1A, 1B, 1C: Detection unit 2: Calculation unit, 21: Comparison unit, 22: Third auscultation signal calculation unit, 23: Storage unit, 3: Output terminal

Claims (3)

A first auscultation signal containing a noisy biological sound is collected from the first auscultation unit of the auscultated person, and a second auscultation unit away from the first auscultation unit contains the noisy biological sound. The detector that collects the auscultation signal of 2 and
A virtual noise signal is generated by comparing the first auscultation signal with the second auscultation signal, and the auscultation signal in the first auscultation unit is obtained from the difference between the first auscultation signal and the virtual noise signal. A biological sound signal processing device including a calculation unit for calculating a third auscultation signal. A step of collecting a first auscultation signal including a noisy biological sound from the first auscultation part of the auscultated person, and
A step of collecting a second auscultation signal including a biological sound that becomes noise from a second auscultation unit away from the first auscultation unit of the auscultated person, and a step of collecting the second auscultation signal.
A step of comparing the first auscultation signal with the second auscultation signal and generating a virtual noise signal included in the first auscultation signal.
A method for processing an internal sound signal, which comprises a step of calculating a third auscultation signal, which is a auscultation signal in the first auscultation unit, from a difference between the first auscultation signal and the virtual noise signal. .. In the biological sound signal processing method according to claim 2,
A biological sound signal processing method, wherein the step of collecting the first auscultation signal and the second auscultation signal is a step of collecting auscultation signal including a heart sound as a biological sound that becomes noise.

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