JP2020199293A - Shunt murmur analyzing device - Google Patents

Abstract

To appropriately support shunt stenosis diagnosis by analyzing shunt murmurs acquired from a subject.SOLUTION: A shunt murmur analyzing device includes acquisition means (110) for acquiring shunt murmur information on shunt murmurs from the periphery of a shunt formation site of a subject, and output means (160) for outputting information indicating an intermittence degree in an acoustic feeling of the shunt murmurs based on the shunt murmur information acquired by the acquisition part. The output information indicating the intermittence degree indicates the possibility of a stenosis occurrence in the shunt formation site quantitatively. Thus, the shunt murmur analyzing device can appropriately support the stenosis diagnosis.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technical field of a shunt sound analyzer for analyzing a shunt sound acquired from a subject, a shunt sound analysis method, a computer program, and a recording medium.

As a device of this type, a device that analyzes a shunt sound acquired from a subject and supports a doctor's diagnosis regarding shunt stenosis or the like is known. For example, in Patent Document 1, an array-shaped sound collection sensor is fixed to the arm of a person to be measured to acquire shunt sounds from a plurality of locations, and the acquired sample data and an index sample including a wide variety of shunt shunt sounds prepared in advance are used. Discloses a shunt sound analyzer that performs analysis by the STMEM method or the like.

Japanese Unexamined Patent Publication No. 2014-8263

However, in the shunt sound analyzer as described in Patent Document 1 described above, not only is it required to prepare a huge amount of index samples in advance when performing analysis, but also it is unique to the person to be measured. Since information and the like are not taken into consideration, there arises a technical problem that accurate analysis results may not be obtained. In addition, the analysis process is complicated, and there is a technical problem that the processing load becomes extremely large.

Examples of the problems to be solved by the present invention include the above. An object of the present invention is to provide a shunt sound analysis device capable of analyzing a shunt sound acquired from a subject to be measured and suitably supporting a shunt stenosis diagnosis.

The shunt sound analyzer for solving the above problems is based on an acquisition means for acquiring shunt sound information related to the shunt sound from the vicinity of the shunt formation site of the person to be measured and the shunt sound information acquired by the acquisition unit. It is provided with an output means for outputting information indicating the degree of audible intermittentness of the shunt sound.

The shunt sound analysis method for solving the above problems is based on an acquisition step of acquiring shunt sound information related to the shunt sound from the vicinity of the shunt formation site of the person to be measured and the shunt sound information acquired in the acquisition step. It includes an output step of outputting information indicating the degree of audible intermittentness of the shunt sound.

A computer program for solving the above problems includes an acquisition step of acquiring shunt sound information regarding a shunt sound from the vicinity of a shunt formation site of a subject, and the shunt sound information acquired in the acquisition step. Have the computer perform an output process that outputs information indicating the degree of audible discontinuity of sound.

The computer program described above is recorded as a recording medium for solving the above problems.

It is a block diagram which shows the whole structure of the shunt sound analysis apparatus which concerns on Example. It is a spectrogram (No. 1) showing an example of a time-frequency waveform. It is a graph which shows an example of a volume analysis waveform. It is a spectrogram (No. 2) showing an example of a time-frequency waveform. It is a graph which shows an example of the frequency center of gravity analysis waveform. It is a flowchart which shows the operation of the individual difference input part. It is a histogram which shows the distribution of the minimum value of the shunt sound accumulated from the past of the subject. It is a histogram which shows the distribution of the maximum value of the shunt sound accumulated from the past of the subject. It is a spectrogram which shows an example of the time frequency waveform of one heartbeat section in a normal state. It is a graph which shows an example of the frequency centroid analysis waveform of one heartbeat section in a normal state. It is a spectrogram which shows an example of the time frequency waveform of one heartbeat section at the time of stenosis occurrence. It is a graph which shows an example of the frequency center of gravity analysis waveform of one heartbeat section at the time of stenosis occurrence. It is a graph which shows an example of the volume change amount of one heartbeat section in a normal state. It is a graph which shows an example of the volume change amount of one heartbeat section at the time of stenosis occurrence. It is a graph which shows an example of the volume minimum value of one heartbeat section in a normal state. It is a graph which shows an example of the volume minimum value of one heartbeat section at the time of stenosis occurrence. It is a graph which shows an example of the volume attenuation rate of one heartbeat section in a normal state. It is a graph which shows an example of the volume attenuation rate of one heartbeat section at the time of stenosis occurrence. It is a graph which shows an example of the volume analysis waveform at the time of distortion occurrence. It is a graph which shows an example of the volume analysis differential waveform at the time of distortion occurrence.

<1>
The shunt sound analyzer according to the present embodiment is the shunt sound analyzer based on the acquisition means for acquiring the shunt sound information regarding the shunt sound from the vicinity of the shunt formation site of the person to be measured and the shunt sound information acquired by the acquisition unit. It is provided with an output means for outputting information indicating the degree of intermittentness in the audibility of sound.

At the time of operation of the shunt sound analyzer according to the present embodiment, first, the shunt sound information regarding the shunt sound is acquired from the vicinity of the shunt forming portion of the person to be measured by the acquisition means. The "shunt sound" here is a blood flow sound acquired around the shunt forming site for taking blood out of the body, and is a sound synchronized with the pulse of the subject. The shunt sound may be acquired by using various sensors, and the acquisition method is not particularly limited. Further, the "shunt sound information" is information including various parameters related to the shunt sound, and includes, for example, time changes such as volume and frequency.

When the shunt sound information is acquired, various analyzes are executed in the output means, and information indicating the degree of audible interruption of the shunt sound is output. The "information indicating the degree of interruption" here does not simply mean information indicating the degree of interruption of the shunt sound, but includes various parameters that cause a feeling of interruption, which is an index when diagnosing stenosis. It means complex information or information in which a plurality of parameters related to a sense of discontinuity are integrated. Information indicating the degree of intermittentness is output, for example, in a numerical state or in a state visualized by a graph or chart.

According to the research by the inventor of the present application, the shunt sound tends to be a large and continuous low sound when the shunt formation site is not narrowed, whereas the shunt sound becomes small as the shunt progresses. Therefore, it has been found that high-pitched sound components due to sound interruptions and turbulent flow at the shunt site appear individually or in combination. Therefore, by using the information indicating the degree of interruption of the shunt sound, it is possible to easily and accurately diagnose whether or not the shunt formation site has a stenosis or the degree of the stenosis. Specifically, the stenosis diagnosis can be easily performed without using the echo diagnosis or the like which has been conventionally used for the stenosis diagnosis. In addition, the information indicating the degree of interruption of the shunt sound enables quantitative diagnosis that does not depend on the skill and experience of the doctor who diagnoses stenosis.

As described above, according to the shunt sound analyzer according to the present embodiment, it is possible to suitably support the diagnosis of stenosis at the shunt forming site.

<2>
In one aspect of the shunt sound analysis device according to the present embodiment, the output means has a volume information deriving means for deriving volume information indicating a change in the volume of the shunt sound with the passage of time based on the shunt sound information. ..

According to this aspect, it is possible to output information indicating the degree of interruption of the shunt sound based on the volume information derived by the volume information deriving means. Here, in particular, according to the research of the inventor of the present application, it has been found that the intermittent feeling of the shunt sound largely depends on the change in the volume of the shunt sound with the passage of time. Therefore, if the derived volume information is used, it is possible to output more appropriate information as information indicating the degree of interruption of the shunt sound.

<3>
In the embodiment provided with the volume information deriving means described above, the output means may have an extraction means for extracting one cycle volume information corresponding to one cycle of the shunt sound from the volume information.

In this case, when the volume information is derived, one cycle volume information corresponding to one cycle of the shunt sound (in other words, one cycle of the pulsation of the person to be measured) is extracted. Therefore, the volume change in one cycle of the shunt sound (for example, the volume change from the systole to the diastole) can be suitably analyzed. Therefore, it is possible to output more appropriate information as information indicating the degree of interruption of the shunt sound.

<4>
In the embodiment including the above-described extraction means, the output means obtains a difference between the maximum value and the minimum value of the volume of the shunt sound in the one-cycle volume information and a difference between the maximum value and the minimum value of the shunt sound in a normal state. In contrast, it may have a first quantifying means for quantifying the degree of interruption.

In this case, first, the minimum value (for example, the volume in the diastole) is subtracted from the maximum value (for example, the volume in the systole period) of the volume of the shunt sound in the one cycle volume information, and the volume change amount in one cycle is calculated. Then, the degree of interruption is quantified by comparing the calculated volume change amount with the volume change amount in the normal state stored in advance.

According to the research by the inventor of the present application, it has been found that the amount of change in volume in one cycle tends to increase as the degree of interruption of the shunt sound increases. Therefore, when the calculated volume change amount is larger than the normal volume change amount, it may be output as a numerical value having a high degree of interruption. On the other hand, when the calculated volume change amount is smaller than the normal volume change amount, it may be output as a numerical value having a low degree of interruption.

<5>
Alternatively, in the embodiment including the extraction means, the output means quantifies the degree of discontinuity by comparing the minimum value of the volume of the shunt sound in the one-cycle volume information with the minimum value of the shunt sound in the normal state. It may have a second quantifying means.

In this case, first, the minimum value of the volume of the shunt sound in the one-cycle volume information (for example, the volume at the end of expansion) is extracted. Then, the degree of discontinuity is quantified by comparing the extracted minimum value with the previously stored minimum value in the normal state.

According to the research by the inventor of the present application, it has been found that as the degree of interruption of the shunt sound increases, the minimum value of the volume in one cycle tends to decrease. Therefore, when the calculated minimum value is larger than the minimum value at the normal time, it may be output as a numerical value having a low degree of interruption. On the other hand, when the calculated minimum value is smaller than the minimum value at the normal time, it may be output as a numerical value having a high degree of interruption.

<6>
Alternatively, in the embodiment including the extraction means, the output means provides a third quantification means for quantifying the degree of interruption based on the slope from the maximum value to the minimum value of the volume of the shunt sound in the one-cycle volume information. You may have.

In this case, first, the slope from the maximum value to the minimum value of the volume of the shunt sound in the one-cycle volume information (in other words, the attenuation rate from the maximum value to the minimum value of the volume) is calculated. Then, the degree of interruption is quantified based on the calculated slope.

According to the research of the inventor of the present application, it has been found that as the degree of interruption of the shunt sound increases, the volume decay tends to increase rapidly from the systole to the diastole. Therefore, the larger the fluctuation of the calculated slope, the higher the degree of intermittentness may be output.

<7>
Alternatively, in the embodiment including the extraction means, the output means compares the difference between the maximum value and the minimum value of the volume of the shunt sound in the one-cycle volume information with the difference between the maximum value and the minimum value of the shunt sound in the normal state. Then, there may be a fourth quantifying means for quantifying the degree of interruption.

In this case, first, the maximum value and the minimum value of the volume of the shunt sound in the one-cycle volume information are extracted. The maximum value and the minimum value can be extracted by using, for example, a smoothed differential waveform. Subsequently, the minimum value is subtracted from the extracted maximum value, and the volume change amount from the maximum value to the minimum value is calculated. Then, the degree of interruption is quantified by comparing the calculated volume change amount with the volume change amount in the normal state stored in advance.

According to the research of the inventor of the present application, as the degree of interruption of the shunt sound increases, the amount of change in volume from the maximum value to the minimum value increases (specifically, the change in volume from systole to diastole). It has been found that it tends to be distorted). Therefore, when the calculated volume change amount is larger than the normal volume change amount, it may be output as a numerical value having a high degree of interruption. On the other hand, when the calculated volume change amount is smaller than the normal volume change amount, it may be output as a numerical value having a low degree of interruption.

<8>
In another aspect of the shunt sound analyzer according to the present embodiment, the output means derives distribution information that indicates the volume of the shunt sound with the passage of time for each frequency based on the shunt sound information. Have a means.

According to this aspect, it is possible to output information indicating the degree of interruption of the shunt sound based on the distribution information derived by the distribution information deriving means. Here, in particular, according to the research of the inventor of the present application, it has been found that the intermittent feeling of the shunt sound largely depends on the distribution of the volume of the shunt sound for each frequency. Therefore, if the derived distribution information is used, it is possible to output more appropriate information as information indicating the degree of interruption of the shunt sound.

<9>
In the embodiment provided with the distribution information deriving means described above, the output means compares the amount of change in the frequency center of gravity with the passage of time indicated by the distribution information with the amount of change in the frequency center of gravity with the passage of time in the normal state. A fifth quantifying means for quantifying the degree of interruption may be provided.

In this case, first, the amount of change in the frequency center of gravity with the passage of time is calculated from the distribution information. The amount of change in the frequency center of gravity can be calculated, for example, by subtracting the minimum center of gravity frequency from the maximum center of gravity frequency. Then, the degree of interruption is quantified by comparing the calculated change amount of the frequency center of gravity with the change amount of the frequency center of gravity stored in advance at the normal time.

According to the research by the inventor of the present application, it has been found that the amount of change in the frequency center of gravity tends to increase (specifically, the high frequency component increases) as the degree of interruption of the shunt sound increases. Therefore, when the calculated change amount of the frequency center of gravity is larger than the change amount of the frequency center of gravity at the normal time, it may be output as a numerical value having a high degree of interruption. On the other hand, when the calculated change amount of the frequency center of gravity is smaller than the change amount of the frequency center of gravity at the normal time, it may be output as a numerical value having a low degree of interruption.

<10>
In another aspect of the shunt sound analyzer according to the present embodiment, the output means has at least two types of the first to fifth digitizing means, and the first to fifth digitizing means are digitized. Each of the above-mentioned discontinuity degrees is determined in an integrated manner, and information indicating the above-mentioned discontinuity degree is output.

According to this aspect, since the quantified discontinuity degree is determined in an integrated manner using different indexes, it is possible to output information indicating a more accurate discontinuity degree. In the integrated determination, for example, the degree of interruption quantified by each quantifying means may be normalized and then given a predetermined weighting. As the information indicating the degree of discontinuity to be output, for example, one value that emphasizes the discontinuity of the hearing, one value that emphasizes the discontinuity of the waveform, or the discontinuity tendency and the waveform discontinuity tendency that match the hearing sensation. The two values shown can be mentioned.

<11>
The shunt sound analysis method according to the present embodiment is based on an acquisition step of acquiring shunt sound information related to the shunt sound from the vicinity of the shunt formation site of the person to be measured and the shunt sound information acquired in the acquisition step. It is provided with an output process that outputs information indicating the degree of intermittentness in the audibility of sound.

According to the shunt sound analysis method according to the present embodiment, information indicating the degree of audible interruption of the shunt sound is output as in the case of the shunt sound analysis device according to the above-described embodiment. Therefore, it is possible to suitably support the diagnosis of stenosis at the shunt forming site.

<12>
The computer program according to the present embodiment has an acquisition step of acquiring shunt sound information related to the shunt sound from the vicinity of the shunt formation site of the subject, and the shunt sound of the shunt sound based on the shunt sound information acquired in the acquisition step. Have the computer perform an output process that outputs information indicating the degree of audible discontinuity.

According to the computer program according to the present embodiment, the computer can execute each step of the shunt sound analysis method according to the above-described embodiment. Therefore, it is possible to suitably support the diagnosis of stenosis at the shunt forming site.

<13>
The computer program described above is recorded on the recording medium according to the present embodiment.

According to the recording medium according to the present embodiment, it is possible to output information indicating the degree of audible discontinuity of the shunt sound by executing the recorded computer program. Therefore, it is possible to suitably support the diagnosis of stenosis at the shunt forming site.

The shunt sound analysis device, the shunt sound analysis method, the operation of the computer program and the recording medium, and other gains according to the present embodiment will be described in more detail in the following examples.

Hereinafter, examples of the shunt sound analyzer will be described in detail with reference to the drawings.

<Device configuration>
First, with reference to FIG. 1, the overall configuration of the shunt sound analyzer according to the present embodiment will be described. Here, FIG. 1 is a block diagram showing an overall configuration of the shunt sound analyzer according to the embodiment.

In FIG. 1, the shunt sound analyzer according to the present embodiment includes an audio signal input unit 110, an audio signal analysis unit 120, an individual difference input unit 130, a global feature extraction unit 140, and a local feature extraction unit 150. The integrated determination unit 160 and the display unit 170 are provided.

The audio signal input unit 110 is composed of, for example, a vibration sensor or the like, and detects a shunt sound from a shunt forming portion of the person to be measured. The shunt sound detected by the audio signal input unit 110 is output to the audio signal analysis unit 120 as an audio signal. The audio signal input unit 110 is a specific example of the “acquisition unit”.

The audio signal analysis unit 120 performs time-frequency analysis on the audio signal input from the audio signal input unit 110. The analysis result by the voice signal analysis unit 120 is output to each of the global feature extraction unit 140 and the local feature extraction unit 150.

The individual difference input unit 130 calculates a parameter indicating a shunt sound peculiar to the person to be measured based on a volume waveform acquired in advance from the person to be measured. The parameters unique to the person to be measured calculated by the individual difference input unit 130 are output to each of the global feature extraction unit 140 and the local feature extraction unit 150.

The global feature extraction unit 140 has the global feature (specifically, the amount of change in the frequency center of gravity, the amount of change in the volume of one heartbeat section, and the minimum value of the volume in one heartbeat section, among the factors that produce the intermittent feeling of the shunt sound. ) Is extracted, and information indicating the degree of interruption is calculated based on each feature. The global feature extraction unit 140 considers the information unique to the person to be measured input from the individual difference input unit 130 when extracting the global feature. The information indicating the degree of discontinuity calculated by the global feature extraction unit 140 is output to the integrated determination unit 160, respectively.

The local feature extraction unit 150 extracts local features (specifically, the volume attenuation rate of one heartbeat section and the distortion of the volume change) from the factors that produce the intermittent feeling of the shunt sound, and is based on each feature. Information indicating the degree of intermittentness is calculated. The local feature extraction unit 150 considers the information unique to the person to be measured input from the individual difference input unit 130 when extracting the local feature. The information indicating the degree of discontinuity calculated by the local feature extraction unit 150 is output to the integrated determination unit 160, respectively.

The integrated determination unit 160 comprehensively determines the information indicating the degree of interruption of the shunt sound input from the global feature extraction unit 140 and the local feature extraction unit 150, and calculates information indicating the possibility of stenosis at the shunt formation site. To do. The information indicating the possibility of stenosis calculated by the integrated determination unit 160 is output to the display unit 170. The integrated determination unit 160 is a specific example of the “output unit”.

The display unit 170 is configured as, for example, a liquid crystal display or the like, and information indicating the possibility of stenosis (information indicating the degree of interruption of the shunt sound) output from the integrated determination unit 160 is visually displayed to a user such as a doctor. It is configured so that it can be presented to. Further, the display unit 170 determines any of the above-mentioned change amount of the frequency center of gravity, the volume change amount in the heartbeat section, the volume minimum value in the heartbeat section, the volume attenuation rate in the heartbeat section, and the distortion of the volume change. It may be presented visually.

<Operation explanation>
Next, the operation of the shunt sound analyzer according to this embodiment will be described. In the following, among the parts of the shunt sound analyzer according to the present embodiment, the parts peculiar to the present embodiment (that is, the voice signal analysis unit 120, the individual difference input unit 130, the global feature extraction unit 140, The operations of the local feature extraction unit 150 and the integrated determination unit 160) will be described in detail.

<Voice signal analysis unit>
First, the operation of the voice signal analysis unit 120 will be specifically described with reference to FIGS. 2 to 5. Here, FIG. 2 is a spectrogram (No. 1) showing an example of a time-frequency waveform, and FIG. 3 is a graph showing an example of a volume analysis waveform. Further, FIG. 4 is a spectrogram (No. 2) showing an example of a time-frequency waveform, and FIG. 5 is a graph showing an example of a frequency center of gravity analysis waveform.

In FIG. 2, the audio signal analysis unit 120 performs time-frequency analysis of the audio signal input from the audio signal input unit 110, and acquires a time-frequency waveform. The time frequency waveform shows the power of each frequency of the shunt sound in chronological order. The audio signal analysis unit 120 calculates the volume of the shunt sound from the time frequency waveform. Specifically, the voice signal analysis unit 120 calculates the volume y (t) of the shunt sound by using the following mathematical formula (1).

Note that f (n) is the frequency and p (n) is the power at the frequency f (n).

As shown in FIG. 3, the volume analysis waveform calculated by the voice signal analysis unit 120 (that is, the waveform indicating the time change of the volume of the shunt sound) is a periodic waveform according to the pulsation of the subject. The volume analysis waveform is divided for each heartbeat section and then output to the global feature extraction unit 140 and the local feature extraction unit 150, which are used for extracting the global feature and the local feature, respectively.

In FIG. 4, the audio signal analysis unit 120 further calculates the frequency center of gravity of the shunt sound from the time frequency waveform. Specifically, the voice signal analysis unit 120 calculates the frequency center of gravity g (t) of the shunt sound by using the following mathematical formula (2).

As shown in FIG. 5, the frequency center of gravity analysis waveform calculated by the voice signal analysis unit 120 (that is, the waveform showing the time change of the frequency center of shunt sound) responds to the pulsation of the person to be measured, similarly to the volume analysis waveform. It becomes a periodic waveform. The frequency center of gravity analysis waveform is output to the global feature extraction unit 140, and is used for extracting the global feature (specifically, the change in the frequency center of gravity).

<Individual difference input section>
Next, the operation of the individual difference input unit 130 will be specifically described with reference to FIGS. 6 to 8. Here, FIG. 6 is a flowchart showing the operation of the individual difference input unit 130. Further, FIG. 7 is a histogram showing the distribution of the minimum value of the shunt sound accumulated from the past of the subject, and FIG. 8 is a histogram showing the distribution of the maximum value of the shunt sound accumulated from the past of the subject. Is.

In FIG. 6, the individual difference input unit 130 calculates a parameter peculiar to the person to be measured from the voice signal acquired in advance. Specifically, in the individual difference input unit 130, when the voice signal is acquired (step S101), the volume analysis waveform is acquired by the volume analysis (step S102). The volume analysis waveform is divided into units of one heartbeat section (step S103), and the maximum value and the minimum value in each section are detected (step S104). The detected maximum and minimum values are stored in the memory (step S105), and the most frequent value from the histogram is determined as the volume maximum value and volume minimum value of the shunt sound peculiar to the subject. (Step S106).

In FIGS. 7 and 8, when the detection frequencies of the minimum value and the maximum value are distributed as shown in the figure, the minimum volume value of the shunt sound peculiar to the subject is determined to be about 137. Similarly, the maximum volume of the shunt sound peculiar to the subject is determined to be about 425.

The specific volume maximum value and volume minimum value of the subject to be measured thus determined are used for individual difference correction of the volume of the shunt sound obtained as the volume analysis waveform. For the corrected volume Y (t), the average value of the volume y (t) obtained by the volume analysis is y_ave, the maximum value is y_max, the minimum value is y_min, and the maximum value of the volume peculiar to the subject is Y_max and the minimum value. Assuming that the value is Y_min, it can be calculated using the following mathematical formula (3).

Y (t) = y_ave + (y (t) -y_ave) × (y_max-y_min) / (Y_max-Y_min) ... (3)
Although the description here is omitted, the maximum value and the minimum value peculiar to each person to be measured may be determined for the frequency center of gravity. The individual difference correction of the frequency center of gravity can also be performed by the same method as the individual difference correction of the volume described above.

<Overview feature extraction section>
Next, the operation of the global feature extraction unit 140 will be specifically described with reference to FIGS. 9 to 16. In the following, a method of calculating the degree of discontinuity for each feature of a plurality of features that can be extracted by the global feature extraction unit 140 will be described.

<Amount of change in frequency center of gravity in one heartbeat section>
First, a method of calculating the degree of discontinuity based on the amount of change in the frequency center of gravity of one heartbeat section will be described with reference to FIGS. 9 to 12. Here, FIG. 9 is a spectrogram showing an example of a time frequency waveform of one heartbeat section in a normal state, and FIG. 10 is a graph showing an example of a frequency center of gravity analysis waveform of one heartbeat section in a normal state. Further, FIG. 11 is a spectrogram showing an example of a time-frequency waveform of one heartbeat section when stenosis occurs, and FIG. 12 is a graph showing an example of a frequency center of gravity analysis waveform of one heartbeat section when stenosis occurs.

In FIGS. 9 and 10, the normal shunt sound is detected as a sound containing many low frequencies. As can be seen from FIG. 10, the minimum value of the frequency center of gravity of the shunt sound under normal conditions is about 610 Hz, and the maximum value is about 700 Hz. Therefore, the amount of change in the frequency center of gravity of the shunt sound (that is, the maximum value-minimum value) in the normal state is about 90 Hz.

In FIGS. 11 and 12, the shunt sound when stenosis occurs (that is, the feeling of interruption is strong) is detected as a sound containing a large amount of high-frequency components as compared with the normal state. As can be seen from FIG. 12, the minimum value of the frequency center of gravity of the shunt sound when stenosis occurs is about 590 Hz, and the maximum value is about 740 Hz. Therefore, the amount of change in the frequency center of gravity of the shunt sound (that is, the maximum value-minimum value) when the stenosis occurs is about 150 Hz.

As can be seen from the above results, there is a clear difference in the amount of change in the frequency center of gravity in one heartbeat section between the normal shunt sound and the shunt sound when stenosis occurs. Therefore, by comparing the amount of change in the frequency center of gravity obtained by the frequency center of gravity analysis with the amount of change in the frequency center of gravity in the normal state, the possibility of stenosis (that is, the degree of interruption of the shunt sound) can be suitably calculated.

<Volume change in one heartbeat section>
Next, a method of calculating the degree of interruption based on the amount of change in volume in one heartbeat section will be described with reference to FIGS. 13 and 14. Here, FIG. 13 is a graph showing an example of the amount of change in volume in one heartbeat section in a normal state. Further, FIG. 14 is a graph showing an example of the amount of change in volume in one heartbeat section when stenosis occurs.

In FIG. 13, in the normal shunt sound, the difference between the maximum value and the minimum value of the volume in one heartbeat section is small. That is, in the normal shunt sound, the amount of change in volume from the systole to the diastole is relatively small.

In FIG. 14, in the shunt sound when stenosis occurs, the difference between the maximum value and the minimum value of the volume in one heartbeat section is larger than that in the normal state. That is, the amount of change in volume of the shunt sound when stenosis occurs is relatively large from the systole to the diastole.

Therefore, the possibility of stenosis (that is, the degree of interruption of the shunt sound) depends on how much the volume change amount in one heartbeat section obtained from the volume analysis waveform is larger than the volume change amount in one heartbeat section in the normal state. Can be preferably calculated.

<Minimum volume in one heartbeat section>
Next, a method of calculating the degree of discontinuity based on the minimum volume value in one heartbeat section will be described with reference to FIGS. 15 and 16. Here, FIG. 15 is a graph showing an example of the minimum volume value in one heartbeat section in a normal state. Also, FIG. It is a graph which shows an example of the volume minimum value of one heartbeat section at the time of stenosis occurrence.

In FIG. 15, in the normal shunt sound, the minimum value of the volume in one heartbeat section is relatively large. Specifically, the normal shunt sound is maintained at a relatively high volume even during the diastole when the volume is low.

In FIG. 16, in the shunt sound when stenosis occurs, the minimum value of the volume in one heartbeat section is larger than that in the normal state. Specifically, the shunt sound at the time of occurrence of stenosis increases to a value close to the normal state with respect to the volume during systole, but the volume during diastole is greatly attenuated.

Therefore, the possibility of stenosis (that is, the degree of interruption of the shunt sound) depends on how small the minimum volume value in one heartbeat section obtained from the volume analysis waveform is smaller than the minimum volume value in one heartbeat section under normal conditions. Can be preferably calculated.

<Local feature extraction unit>
Next, the operation of the local feature extraction unit 150 will be specifically described with reference to FIGS. 17 to 20. In the following, a method of calculating the degree of discontinuity for each feature of a plurality of features that can be extracted by the local feature extraction unit 150 will be described.

<Volume attenuation rate in one heartbeat section>
First, a method of calculating the degree of interruption based on the volume attenuation rate of one heartbeat section will be described with reference to FIGS. 17 and 18. Here, FIG. 17 is a graph showing an example of the volume attenuation rate of one heartbeat section in a normal state. Further, FIG. 18 is a graph showing an example of the volume attenuation rate in one heartbeat section when stenosis occurs.

In FIG. 17, in the normal shunt sound, the attenuation of the volume in one heartbeat section is linear. Specifically, in the normal shunt sound, the slope (attenuation factor) from the maximum value to the minimum value of the volume is constant.

In FIG. 18, in the shunt sound when the stenosis occurs, there is a portion where the volume is rapidly attenuated in one heartbeat section. Specifically, in the shunt sound when stenosis occurs, the volume decreases remarkably from the end of contraction to the beginning of diastole, and then decreases relatively slowly. Therefore, the slope (attenuation factor) from the maximum value to the minimum value of the volume is not constant.

Therefore, the possibility of stenosis (that is, the degree of interruption of the shunt sound) can be suitably calculated by using the volume attenuation rate in one heartbeat section obtained from the volume analysis waveform. The attenuation factor dr can be calculated using the following mathematical formula (4).

Note that N is the number of data in one heartbeat section, and max and min are the maximum and minimum values of the volume in one heartbeat section, respectively. The attenuation rate dr is calculated as a smaller value as the deviation from the linear attenuation rate 0.5 shown by the broken line in FIG. 18 is used as a reference. Therefore, the possibility of stenosis (that is, the degree of interruption of the shunt sound) can be suitably calculated depending on how much the calculated attenuation rate dr is smaller than 0.5.

<Distortion of volume change>
Next, a method of calculating the degree of discontinuity based on the distortion of the volume change that occurs from the systole to the diastole will be described with reference to FIGS. 19 and 20. Here, FIG. 19 is a graph showing an example of the volume analysis waveform when distortion occurs. Further, FIG. 20 is a graph showing an example of a volume analysis differential waveform when distortion occurs.

In FIG. 19, in the shunt sound when stenosis occurs, the change in volume may be distorted from the end of contraction to the beginning of diastole. Specifically, as shown by the portion surrounded by the broken line in the figure, the volume may decrease sharply and then temporarily increase. Therefore, the possibility of stenosis (that is, the degree of interruption of the shunt sound) can be calculated by the existence of the maximum value in the volume analysis waveform.

In FIG. 20, the maximum value in the volume analysis waveform can be easily detected by using a smoothed differential waveform of the volume analysis waveform. Specifically, it is possible to preferably detect by calculating the difference between the maximum value and the minimum value of the differential waveform of the volume analysis waveform.

<Integrated judgment unit>
Finally, the operation of the integrated determination unit 160 will be specifically described. In the following, the feature amount extracted as the change amount of the frequency center of gravity, which is a global feature, is extracted as ρ ₁ , the feature amount extracted as the volume change amount of one heartbeat section is ρ ₂ , and the feature amount extracted as the volume minimum value of one heartbeat section is extracted. feature amount [rho _3, local features in a heart beat ₄ the characteristic amount extracted as volume attenuation factor [rho _sections, illustrating a feature quantity extracted as a distortion of the volume change as [rho _5. In addition, each direct quantity ρ _{1 to} ρ ₅ is normalized (for example, it is adjusted so that the case where the degree of interruption is the strongest is 0 and the case where the degree of interruption is the weakest (that is, normal) is 100). Shall be.

The integrated determination unit 160 weights each feature amount ρ _{1 to} ρ ₅ and calculates the degree of discontinuity. Specifically, the degree of discontinuity is calculated using the following mathematical formula (5), where the weights corresponding to the respective feature quantities ρ _{1 to} ρ ₅ are ω ₁ to ω ₅ .

Intermittent degree = ω ₁ x ρ ₁ + ω ₂ x ρ ₂ + ω ₃ x ρ ₃ + ω ₄ x ρ ₄ + ω ₅ x ρ ₅ ... (5)
Here, when the degree of discontinuity is output as one numerical value with an emphasis on matching the audibility, the relationship of ω1, ω2, ω3 >> ω4, and ω5 may be established for the weights ω _{1 to} ω _5. .. The degree of discontinuity obtained in this way is suitable for determining whether or not dialysis on the day is possible, for example, at an artificial dialysis site.

Further, when the degree of discontinuity is output as one numerical value with an emphasis on the discontinuity of the waveform, the relationship of ω4, ω5>ω2> ω1 and ω3 may be established for the weights ω _{1 to} ω ₅ . The degree of discontinuity obtained in this way is suitable for comparison with, for example, echo diagnosis.

Alternatively, when outputting as two values, a numerical value that emphasizes the degree of discontinuity and a numerical value that emphasizes the discontinuity of the waveform, it is calculated separately using the following mathematical formulas (6) and (7). do it.

Degree of discontinuity due to hearing = ω ₁ × ρ ₁ + ω ₂ × ρ ₂ + ω ₃ × ρ ₃・ ・ ・ (6)
Intermittent degree by waveform = ω ₄ × ρ ₄ + ω ₅ × ρ ₅ ... (7)
The degree of discontinuity obtained in this way is suitable for determining the progress of discontinuity (that is, stenosis) from changes over time in both the auditory sense and the waveform, for example.

It should be noted that each feature amount ρ _{1 to} ρ ₅ may be output independently without performing an integrated determination by the integrated determination unit 160. In this case, for example, numerical values corresponding to each feature amount ρ _{1 to} ρ ₅ are separately displayed on the display unit 170, or are displayed as a radar chart. As a result, the user, such as a doctor, can diagnose the stenosis from a plurality of viewpoints by using each of the feature amounts ρ _{1 to} ρ ₅ . Alternatively, each of the feature amounts ρ _{1 to} ρ ₅ can be used by a doctor or the like to make an integrated judgment by himself / herself to make a stenosis diagnosis.

As described above, according to the shunt sound analysis device according to the present embodiment, information indicating the degree of interruption is output as the analysis result of the shunt sound. Therefore, it is possible to suitably support the diagnosis of stenosis at the shunt formation site.

The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of claims and within a range not contrary to the gist or idea of the invention that can be read from the entire specification, and shunt sound analysis accompanied by such modification. Devices, shunt sound analysis methods, computer programs and recording media are also included in the technical scope of the present invention.

110 Audio signal input unit 120 Audio signal analysis unit 130 Individual difference input unit 140 Global feature extraction unit 150 Local feature extraction unit 160 Integrated judgment unit 170 Display unit

Claims (1)

An acquisition means for acquiring shunt sound information regarding the shunt sound from the vicinity of the shunt formation site of the person to be measured, and
A shunt sound analysis device including an output means for outputting information indicating an audible discontinuity of the shunt sound based on the shunt sound information acquired by the acquisition unit.