WO2016139802A1

WO2016139802A1 - Shunt murmur analysis device, shunt murmur analysis method, computer program, and recording medium

Info

Publication number: WO2016139802A1
Application number: PCT/JP2015/056530
Authority: WO
Inventors: 太郎中島; 真一莪山; 祐介曽我
Original assignee: パイオニア株式会社
Priority date: 2015-03-05
Filing date: 2015-03-05
Publication date: 2016-09-09
Also published as: JPWO2016139802A1

Abstract

A shunt murmur analysis device is provided with an acquiring means (110) for acquiring shunt murmur information relating to a shunt murmur from the area of a site where a shunt is formed in a measurement subject, and an output means (160) for outputting information indicating the degree of continuity of shunt murmur audibility on the basis of the shunt murmur information acquired by an acquiring unit. The outputted information indicating the degree of continuity quantitatively indicates the likelihood of stenosis at the shunt formation site. Consequently, the shunt murmur analysis device makes it possible to appropriately assist in diagnosing stenosis.

Description

Shunt sound analysis device, shunt sound analysis method, computer program, and recording medium

The present invention relates to a technical field of a shunt sound analysis device, a shunt sound analysis method, a computer program, and a recording medium that analyze a shunt sound acquired from a measurement subject.

As this type of device, there is known a device that analyzes a shunt sound acquired from a measurement subject and supports a doctor's diagnosis regarding shunt stenosis or the like. For example, in Patent Document 1, an arrayed sound collection sensor is fixed to a measurement subject's arm and shunt sounds are acquired from a plurality of locations. The acquired sample data and index samples including a variety of shunt stenosis sounds prepared in advance are provided. Is disclosed a shunt sound analyzer for performing analysis by the STMEM method or the like.

JP 2014-8263 A

However, in the shunt sound analyzer as described in Patent Document 1 described above, it is not only required to prepare an enormous amount of index samples in advance when performing the analysis, but is also specific to the person being measured. Since no information is taken into account, there is a technical problem that an accurate analysis result may not be obtained. Further, the analysis processing is complicated, and a technical problem that the processing load becomes extremely large also arises.

Examples of problems to be solved by the present invention include the above. It is an object of the present invention to provide a shunt sound analysis device that can analyze a shunt sound acquired from a measurement subject and favorably support a diagnosis of shunt stenosis.

The shunt sound analyzer for solving the above problems is based on the shunt sound information about the shunt sound from the periphery of the measurement subject's shunt formation site, and the shunt sound information acquired by the acquisition unit. Output means for outputting information indicating the degree of intermittentness of the shunt sound.

The shunt sound analysis method for solving the above problem is based on the shunt sound information acquired in the acquisition step, the acquisition step of acquiring shunt sound information about the shunt sound from the periphery of the measurement subject's shunt formation site, And an output step of outputting information indicating the degree of continuity of the shunt sound.

A computer program for solving the above-described problems is an acquisition step of acquiring shunt sound information related to a shunt sound from the periphery of a shunt formation site of the measurement subject, and the shunt sound information based on the shunt sound information acquired in the acquisition step. And causing the computer to execute an output step of outputting information indicating the degree of intermittentness in sound perception.

The recording medium for solving the above problem is recorded with the computer program described above.

It is a block diagram which shows the whole structure of the shunt sound analyzer which concerns on an Example. It is a spectrogram (the 1) which shows an example of a time frequency waveform. It is a graph which shows an example of a sound volume analysis waveform. It is a spectrogram (the 2) which shows an example of a time frequency waveform. It is a graph which shows an example of a frequency gravity center analysis waveform. It is a flowchart which shows operation | movement of an individual difference input part. It is a histogram which shows distribution of the minimum value of the shunt sound accumulate | stored from the past of a to-be-measured person. It is a histogram which shows distribution of the maximum value of the shunt sound accumulate | stored from the past of a to-be-measured person. It is a spectrogram which shows an example of the time frequency waveform of one heartbeat area at the time of normal. It is a graph which shows an example of the frequency center-of-gravity analysis waveform of one heartbeat section at the normal time. It is a spectrogram which shows an example of the time-frequency waveform of 1 heartbeat area at the time of stenosis generation | occurrence | production. 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 variation | change_quantity of 1 heartbeat area at the time of normal. It is a graph which shows an example of the volume variation | change_quantity in 1 heartbeat area at the time of stenosis generation | occurrence | production. It is a graph which shows an example of the volume minimum value of one heartbeat section at the time of normal. It is a graph which shows an example of the sound volume minimum value of one heart beat section at the time of stenosis occurrence. It is a graph which shows an example of the volume attenuation rate of 1 heartbeat section at the time of normal. It is a graph which shows an example of the sound volume attenuation rate of 1 heartbeat area at the time of stenosis occurrence. It is a graph which shows an example of the volume analysis waveform at the time of distortion generation. It is a graph which shows an example of the volume analysis differential waveform at the time of distortion generation.

<1>
The shunt sound analysis apparatus according to the present embodiment is based on the shunt sound information acquired by the acquisition unit that acquires shunt sound information related to the shunt sound from the periphery of the measurement subject's shunt formation site, and the shunt sound information acquired by the acquisition unit. Output means for outputting information indicating the degree of intermittentness of sound.

In the operation of the shunt sound analysis apparatus according to the present embodiment, shunt sound information related to the shunt sound is first acquired from the periphery of the measurement subject's shunt formation region by the acquisition means. Here, the “shunt sound” is a blood flow sound acquired in the vicinity of a shunt formation site for taking blood out of the body, and is a sound synchronized with the pulse of the measurement subject. The acquisition of the shunt sound may be performed using various sensors, and the acquisition method is not particularly limited. The “shunt sound information” is information including various parameters related to the shunt sound, and includes, for example, temporal changes such as volume and frequency.

When the shunt sound information is acquired, various types of analysis are executed in the output means, and information indicating the degree of intermittentness of the shunt sound is output. Here, “information indicating the degree of intermittent” does not simply mean information indicating the degree to which the shunt sound is interrupted, but includes various parameters that cause an intermittent feeling that is used as an index when stenosis is diagnosed. It means complex information or information in which a plurality of parameters related to a sense of intermittentness are integrated. Note that the information indicating the degree of intermittentness is output, for example, in a digitized state or in a state visualized by a graph or chart.

According to the study by the present inventor, when the stenosis does not occur in the shunt formation site, the shunt sound tends to be a large and continuous low sound, whereas when the stenosis progresses, the shunt sound becomes small. Therefore, it has been found that a high sound component due to sound interruption or turbulent flow in a constricted region appears alone or in combination. Therefore, if information indicating the degree of intermittent shunt sound is used, it is possible to easily and accurately diagnose whether or not a stenosis has occurred in a shunt formation site. Specifically, the stenosis diagnosis can be easily performed without using the echo diagnosis or the like conventionally used for the stenosis diagnosis. Moreover, quantitative information independent of the skill and experience of a doctor who diagnoses stenosis can be obtained based on information indicating the degree of intermittent shunt sound.

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

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

According to this aspect, based on the sound volume information derived by the sound volume information deriving means, it is possible to output information indicating the degree of shunt sound interruption. Here, in particular, according to the study by the present inventor, it has been found that the discontinuity of the shunt sound largely depends on the change in the volume of the shunt sound over time. Therefore, by using the derived volume information, more appropriate information can be output as information indicating the degree of intermittent shunt sound.

<3>
In the aspect including the volume information deriving unit described above, the output unit may include an extraction unit that extracts 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-period volume information corresponding to one period of the shunt sound (in other words, one period of the pulsation of the measured person) is extracted therefrom. For this reason, the volume change (for example, volume change from the systole to the diastole) in one cycle of the shunt sound can be suitably analyzed. Therefore, it is possible to output more appropriate information as information indicating the degree of intermittent shunt sound.

<4>
In the aspect provided with the extraction means described above, the output means calculates the difference between the maximum value and the minimum value of the shunt sound volume in the one-period sound volume information, and the difference between the maximum value and the minimum value of the shunt sound at normal time. In contrast, a first digitizing means for digitizing the degree of intermittentness may be provided.

In this case, first, the minimum value (for example, diastole volume) is subtracted from the maximum value (for example, systolic volume) of the shunt sound volume in the one-cycle volume information, and the volume change amount in one cycle is obtained. Then, the calculated volume change amount is compared with a previously stored volume change amount at the normal time, whereby the degree of intermittentness is quantified.

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

<5>
Alternatively, in an aspect including the extraction means, the output means compares the minimum value of the shunt sound volume in the one-period sound volume information with the minimum value of the shunt sound in a normal state, and quantifies the degree of intermittentness. You may have a 2nd numerical conversion means.

In this case, first, the minimum value of the shunt sound volume (for example, the volume at the end of diastole) in the one-cycle volume information is extracted. Then, the extracted minimum value is compared with the previously stored minimum value at normal time, whereby the degree of intermittentness is digitized.

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

<6>
Alternatively, in an aspect including an extraction unit, the output unit includes a third quantification unit that quantifies the degree of intermittence based on a slope from a maximum value to a minimum value of the shunt sound volume in the one-period sound volume information. You may have.

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

According to the research conducted by the present inventors, it has been found that the attenuation of the volume from the systole to the diastole tends to become sharper when the intermittent degree of the shunt sound increases. Therefore, it is only necessary to output a numerical value with a higher degree of interruption as the calculated variation in inclination is larger.

<7>
Alternatively, in an aspect including the extraction means, the output means compares the difference between the maximum value and the minimum value of the shunt sound volume in the one-period sound volume information with the difference between the maximum value and the minimum value of the shunt sound at normal time. And you may have the 4th digitization means which digitizes the said intermittent degree.

In this case, first, the maximum value and the minimum value of the shunt sound volume in the one-cycle volume information are extracted. The maximum value and the minimum value can be extracted 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 obtained. Then, the calculated volume change amount is compared with a previously stored volume change amount at the normal time, whereby the degree of intermittentness is quantified.

According to the research conducted by the present inventor, when the intermittent level of the shunt sound increases, the volume change amount from the maximum value to the minimum value increases (specifically, the change in the volume from the systole to the diastole). It has been found that there is a tendency for distortion to occur. Therefore, when the calculated volume change amount is larger than the normal volume change amount, it may be output as a numerical value with a high degree of intermittentness. On the other hand, if the calculated volume change amount is smaller than the normal volume change amount, it may be output as a numerical value with a low degree of intermittentness.

<8>
In another aspect of the shunt sound analysis apparatus according to the present embodiment, the output means derives distribution information that derives distribution information indicating the volume of the shunt sound over time for each frequency based on the shunt sound information. Have means.

According to this aspect, based on the distribution information derived by the distribution information deriving means, it is possible to output information indicating the degree of intermittent shunt sound. In particular, according to the study by the present inventors, it has been found that the discontinuity of the shunt sound greatly depends on the distribution of the volume of the shunt sound for each frequency. Therefore, if the derived distribution information is used, more appropriate information can be output as information indicating the degree of intermittent shunt sound.

<9>
In the aspect including the distribution information deriving unit described above, the output unit compares the amount of change of the frequency centroid with the passage of time indicated by the distribution information with the amount of change of the frequency centroid with the passage of time in normal time, You may have the 5th digitization means which digitizes the said intermittent degree.

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 centroid can be calculated, for example, by subtracting the minimum centroid frequency from the maximum centroid frequency. Then, the calculated degree of change in the frequency centroid is compared with the amount of change in the frequency centroid at normal time stored in advance, whereby the degree of intermittence is digitized.

According to the research conducted by the present inventor, 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 intermittent shunt sound increases. Therefore, when the calculated change amount of the frequency centroid is larger than the normal change amount of the frequency centroid, it may be output as a numerical value with a high degree of intermittentness. On the other hand, when the calculated change amount of the frequency centroid is smaller than the normal change amount of the frequency centroid, it may be output as a numerical value with a low degree of intermittentness.

<10>
In another aspect of the shunt sound analysis apparatus according to the present embodiment, the output means includes at least two types of the first to fifth digitizing means, and the first to fifth digitizing means digitize. Each of the determined degrees of interruption is determined in an integrated manner, and information indicating the degree of interruption is output.

According to this aspect, since the digitized intermittent degree is determined by using different indexes, information indicating the more accurate intermittent degree can be output. When integrated determination is performed, for example, a predetermined weighting may be performed after normalizing the degree of intermittence digitized by each numerical means. In addition, as the information indicating the degree of discontinuity to be output, for example, one value that emphasizes the audibility, one value that emphasizes the continuity of the waveform, or the discontinuity tendency and the waveform discontinuity tendency that suit the audibility. Two values are shown.

<11>
The shunt sound analysis method according to the present embodiment includes the acquisition step of acquiring shunt sound information related to the shunt sound from the periphery of the measurement subject's shunt formation site, and the shunt sound information acquired based on the shunt sound information acquired in the acquisition step. And an output step of outputting information indicating the degree of intermittentness in sound audibility.

According to the shunt sound analysis method according to the present embodiment, information indicating the degree of audibility of the shunt sound is output in the same manner as the shunt sound analysis apparatus according to the present embodiment described above. Therefore, it is possible to favorably support the diagnosis of stenosis at the shunt formation site.

<12>
The computer program according to the present embodiment obtains shunt sound information related to a shunt sound from the periphery of the measurement subject's shunt formation, and the shunt sound information based on the shunt sound information obtained in the acquisition step. And causing the computer to execute an output step of outputting information indicating the degree of audible discontinuity.

The computer program according to the present embodiment can cause the computer to execute each step of the shunt sound analysis method according to the present embodiment described above. Therefore, it is possible to favorably support the diagnosis of stenosis at the shunt formation site.

<13>
The recording medium according to the present embodiment records the above-described computer program.

According to the recording medium according to the present embodiment, it is possible to output information indicating the degree of intermittent audibility of the shunt sound by executing the recorded computer program. Therefore, it is possible to favorably support the diagnosis of stenosis at the shunt formation site.

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

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

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

In FIG. 1, the shunt sound analysis apparatus 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. And an integrated determination unit 160 and a display unit 170.

The audio signal input unit 110 is configured by, for example, a vibration sensor or the like, and detects a shunt sound from a shunt formation site of the measurement subject. 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 “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 audio 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 unique to the measurement subject based on a volume waveform acquired from the measurement subject in advance. The parameter unique to the measurement subject calculated by the individual difference input unit 130 is output to each of the global feature extraction unit 140 and the local feature extraction unit 150.

The global feature extraction unit 140 includes a global feature (specifically, a change amount of the frequency centroid, a change amount of the volume of the heartbeat interval, and a minimum volume value of the heartbeat interval) among the factors that generate the intermittent feeling of the shunt sound. ) And information indicating the degree of intermittentness is calculated based on each feature. Note that the global feature extraction unit 140 considers information unique to the measurement subject input from the individual difference input unit 130 when extracting the global feature. Information indicating the degree of intermittence calculated by the global feature extraction unit 140 is configured to be output to the integration determination unit 160, respectively.

The local feature extraction unit 150 extracts local features (specifically, the volume attenuation rate of one heartbeat interval and the distortion of the volume change) from the factors that generate the intermittent feeling of the shunt sound, and based on each feature. To calculate information indicating the intermittent degree. The local feature extraction unit 150 considers information unique to the measurement subject input from the individual difference input unit 130 when extracting the local features. Information indicating the degree of intermittence calculated by the local feature extraction unit 150 is configured to be output to the integration determination unit 160, respectively.

The integrated determination unit 160 comprehensively determines information indicating the degree of intermittent 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. 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 an “output unit”.

The display unit 170 is configured, for example, as a liquid crystal display or the like, and displays information indicating the possibility of stenosis (information indicating the degree of intermittent shunt sound) output from the integrated determination unit 160 to a user such as a doctor. It is configured to be able to present. Further, the display unit 170 displays any one of the above-described change amount of the frequency centroid, 1 volume change amount of the heartbeat interval, 1 volume minimum value of the heartbeat interval, 1 volume attenuation rate of the heartbeat interval, and distortion of the volume change. It may be presented visually.

<Description of operation>
Next, the operation of the shunt sound analyzer according to the present embodiment will be described. In the following, among the parts of the shunt sound analysis apparatus according to the present embodiment, the parts specific to the present embodiment (that is, the sound 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 integration determination unit 160) will be described in detail.

<Audio signal analysis unit>
First, the operation of the audio signal analysis unit 120 will be specifically described with reference to FIGS. 2 to 5. FIG. 2 is a spectrogram (part 1) showing an example of the time-frequency waveform, and FIG. 3 is a graph showing an example of the volume analysis waveform. FIG. 4 is a spectrogram (part 2) showing an example of a time-frequency waveform, and FIG. 5 is a graph showing an example of a frequency centroid 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 indicates the power for each frequency of the shunt sound in time series. The audio signal analysis unit 120 calculates the volume of the shunt sound from the time frequency waveform. Specifically, the audio signal analysis unit 120 calculates the shunt sound volume y (t) using the following 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 audio signal analysis unit 120 (that is, a waveform indicating the time change of the volume of the shunt sound) is a periodic waveform according to the pulsation of the measurement subject. The volume analysis waveform is divided for each heartbeat interval, and then output to the global feature extraction unit 140 and the local feature extraction unit 150, and is used to extract the global feature and the local feature, respectively.

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

As shown in FIG. 5, the frequency centroid analysis waveform calculated by the audio signal analysis unit 120 (that is, the waveform indicating the time change of the frequency centroid of the shunt sound) corresponds to the pulsation of the measurement subject, similarly to the volume analysis waveform. A periodic waveform. The frequency centroid analysis waveform is output to the global feature extraction unit 140, and is used to extract global features (specifically, changes in the frequency centroid).

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

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

7 and 8, when the detection frequency of the minimum value and the maximum value has a distribution as shown in the figure, the minimum volume value of the shunt sound unique to the measured person is determined to be about 137. Similarly, the maximum volume value of the measurement subject's unique shunt sound is determined to be about 425.

The specific volume maximum value and volume minimum value of the measurement subject thus determined are used for individual difference correction of the volume of the shunt sound obtained as the volume analysis waveform. The corrected volume Y (t) is y_ave, the maximum value y_max, the minimum value y_min, and the maximum value Y_max, the minimum value unique to the measurement subject, Y_max If 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)
In addition, although description here is abbreviate | omitted, the intrinsic | native maximum value and minimum value for every to-be-measured person may be determined also about a frequency gravity center. The individual difference correction of the frequency centroid can also be performed by the same method as the above-described individual difference correction of the volume.

<Global Feature Extraction Unit>
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 for calculating the degree of continuity for each of the features that can be extracted by the global feature extraction unit 140 will be described.

<Change in the frequency center of gravity during one heartbeat interval>
First, with reference to FIG. 9 to FIG. 12, a method for calculating the degree of intermittence based on the amount of change in the frequency center of gravity in one heartbeat interval will be described. FIG. 9 is a spectrogram showing an example of a time-frequency waveform of one heartbeat section at normal time, and FIG. 10 is a graph showing an example of a frequency barycentric analysis waveform of one heartbeat section at normal time. 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 centroid analysis waveform of one heartbeat section when stenosis occurs.

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 in a normal state is about 610 Hz, and the maximum value is about 700 Hz. Therefore, the amount of change in the frequency centroid of the shunt sound in a normal state (that is, the maximum value−minimum value) is about 90 Hz.

11 and 12, the shunt sound at the time of occurrence of stenosis (that is, a strong sense of intermittentness) is detected as a sound containing a lot of high frequency components as compared with the normal time. As can be seen from FIG. 12, the minimum value of the frequency centroid 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 centroid of the shunt sound when stenosis occurs (that is, the maximum value−minimum value) is about 150 Hz.

As can be seen from the above results, there is a clear difference in the change in the frequency center of gravity in one heartbeat interval between the normal shunt sound and the shunt sound when stenosis occurs. Therefore, if the change amount of the frequency centroid obtained by the frequency centroid analysis is compared with the change amount of the frequency centroid at the normal time, the possibility of occurrence of stenosis (that is, the degree of intermittent shunt sound) can be suitably calculated.

<Volume change in one heartbeat section>
Next, with reference to FIG. 13 and FIG. 14, a method for calculating the intermittent degree based on the volume change amount in one heartbeat interval will be described. FIG. 13 is a graph showing an example of the volume change amount in one heartbeat section at the normal time. FIG. 14 is a graph showing an example of the volume change amount in one heartbeat interval 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 interval is small. That is, the normal shunt sound has a relatively small volume change amount from the systole to the diastole.

In FIG. 14, in the shunt sound at the time of occurrence of stenosis, 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 shunt sound when stenosis occurs has a relatively large volume change amount from the systole to the diastole.

Therefore, the possibility of occurrence of stenosis (that is, the degree of intermittent shunt sound) depends on how much the volume change amount in one heart beat interval obtained from the sound volume analysis waveform is larger than the volume change amount in one heart beat interval at normal time. Can be suitably calculated.

<Minimum volume for one heartbeat section>
Next, with reference to FIG.15 and FIG.16, the calculation method of the intermittent degree based on the volume minimum value of 1 heartbeat area is demonstrated. FIG. 15 is a graph showing an example of the minimum volume value in one heartbeat section at normal time. FIG. It is a graph which shows an example of the sound volume minimum value of one heart beat 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 in the expansion period when the volume is low.

In FIG. 16, in the shunt sound at the time of occurrence of stenosis, the minimum value of the volume in one heart beat 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 normal in the systolic volume, but the volume in the diastole is greatly attenuated.

Therefore, the possibility of occurrence of stenosis (that is, the degree of intermittent shunt sound) depends on how small the minimum volume value in one heart beat interval obtained from the sound volume analysis waveform is compared with the minimum sound volume value in one heart beat interval at normal time. Can be suitably 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 for calculating the degree of intermittentness for each of the features that can be extracted by the local feature extraction unit 150 will be described.

<Volume attenuation rate in one heartbeat section>
First, with reference to FIG.17 and FIG.18, the calculation method of the intermittent degree based on the volume attenuation rate of 1 heartbeat area is demonstrated. FIG. 17 is a graph showing an example of the volume attenuation rate of one heartbeat section at normal time. FIG. 18 is a graph showing an example of the volume attenuation rate of one heartbeat interval when stenosis occurs.

Referring to FIG. 17, the normal shunt sound has a linear attenuation of sound volume in one heartbeat interval. Specifically, in a normal shunt sound, the gradient (attenuation rate) from the maximum value to the minimum value of the volume is constant.

In FIG. 18, in the shunt sound at the time of occurrence of stenosis, there is a portion where the volume is sharply attenuated in one heartbeat section. Specifically, in the shunt sound when stenosis occurs, the volume decreases significantly from the end of systole to the beginning of the diastole, and then decreases relatively slowly. For this reason, the gradient (attenuation rate) from the maximum value to the minimum value of the sound volume is not constant.

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

Note that N is the number of data in one heartbeat interval, and max and min are the maximum value and the minimum value of the volume in one heartbeat interval, respectively. The attenuation rate dr is calculated as a smaller value with a larger deviation from 0.5, which is a linear attenuation rate indicated by a broken line in FIG. Therefore, the possibility of occurrence of stenosis (that is, the degree of intermittent 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, with reference to FIG. 19 and FIG. 20, a method for calculating the intermittent degree based on the distortion of the volume change that occurs from the systole to the diastole will be described. FIG. 19 is a graph showing an example of a volume analysis waveform when distortion occurs. FIG. 20 is a graph showing an example of a volume analysis differential waveform when distortion occurs.

Referring to FIG. 19, the shunt sound when stenosis occurs may cause distortion in the change in volume from the end of systole to the beginning of diastole. Specifically, like the part surrounded by the broken line in the figure, the volume may increase temporarily after suddenly decreasing. Therefore, the possibility of occurrence of stenosis (that is, the degree of intermittent shunt sound) can be calculated based on the presence 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 detect preferably 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 value extracted as the change amount of the frequency centroid, which is a global feature, is extracted as ρ ₁ , the feature value extracted as the volume change amount of one heartbeat interval is ρ ₂ , and is extracted as the minimum sound volume value of one heartbeat interval. 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. Each of the direct quantities ρ ₁ to ρ ₅ is normalized (for example, adjusted so that the highest intermittent degree is 0 and the weakest case (ie, normal) is 100). Shall.

The integrated determination unit 160 calculates the intermittent degree by weighting the feature amounts ρ ₁ to ρ ₅ . Specifically, the discontinuity is calculated by using the following formula (5), with the weights corresponding to the feature quantities ρ ₁ to ρ ₅ being ω ₁ to ω ₅ .

Intermittent degree = ω ₁ × ρ ₁ + ω ₂ × ρ ₂ + ω ₃ × ρ ₃ + ω ₄ × ρ ₄ + ω ₅ × ρ ₅ (5)
Here, when outputting a single number that emphasizes that fit the intermittency audibly, the weight omega _{1 ~} omega ₅ for ω1, ω2, ω3 >> ω4, may be such that the relationship of ω5 is established . The degree of discontinuity obtained in this way is suitable for determining whether dialysis on the day is possible, for example, at an artificial dialysis site.

Further, when the continuity is output as one numerical value that places importance on the continuity of the waveform, the relationships of ω4, ω5>ω2> ω1, and ω3 may be satisfied with respect to the weights ω ₁ to ω ₅ . The 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 continuity according to the sense of hearing and a numerical value that emphasizes the continuity of the waveform, it is calculated separately using the following formulas (6) and (7). do it.

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

Note that the feature amounts ρ ₁ to ρ ₅ may be output independently without performing the integrated determination by the integrated determination unit 160. In this case, for example, numerical values corresponding to the feature amounts ρ ₁ to ρ ₅ are separately displayed on the display unit 170 or displayed as a radar chart. Thereby, a doctor who is a user can perform stenosis diagnosis from a plurality of viewpoints using each of the feature amounts ρ ₁ to ρ ₅ . Alternatively, using each of the feature quantities ρ ₁ to ρ ₅ , a doctor or the like can make an integrated judgment and make a stenosis diagnosis.

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

The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and shunt sound analysis accompanying such changes is possible. A device, a shunt sound analysis method, a computer program, and a recording medium are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 110 Voice signal input part 120 Voice signal analysis part 130 Individual difference input part 140 Global feature extraction part 150 Local feature extraction part 160 Integrated determination part 170 Display part

Claims

An acquisition means for acquiring shunt sound information related to the shunt sound from the periphery of the measurement subject's shunt formation site;
A shunt sound analysis apparatus comprising: output means for outputting information indicating a degree of audibility of the shunt sound based on the shunt sound information acquired by the acquisition unit.
The shunt sound analysis according to claim 1, wherein the output means includes volume information deriving means for deriving volume information indicating a change in volume of the shunt sound over time based on the shunt sound information. apparatus.
3. The shunt sound analysis apparatus according to claim 2, wherein the output means includes extraction means for extracting one-period sound volume information corresponding to one period of the shunt sound from the sound volume information.
The output means compares the difference between the maximum value and the minimum value of the shunt sound volume in the one-period sound volume information with the difference between the maximum value and the minimum value of the shunt sound in a normal state, and calculates the intermittent degree The shunt sound analyzing apparatus according to claim 3, further comprising a first digitizing unit for converting the first shunt sound into a numerical value.
The output means includes second numerical means for numerically expressing the degree of intermittentness by comparing the minimum value of the shunt sound volume in the one-period sound volume information with the minimum value of the shunt sound in a normal state. The shunt sound analyzer according to claim 3.
The output means comprises third numerical means for numerically expressing the degree of intermittence based on a slope from a maximum value to a minimum value of the shunt sound volume in the one-period sound volume information. 3. The shunt sound analyzer according to 3.
The output means compares the difference between the maximum value and the minimum value of the shunt sound volume in the one-period sound volume information with the difference between the maximum value and the minimum value of the shunt sound in a normal state, and calculates the intermittent degree as a numerical value. 4. The shunt sound analyzing apparatus according to claim 3, further comprising a fourth numerical means for converting into a fourth numerical value.
2. The shunt according to claim 1, wherein the output means includes distribution information deriving means for deriving distribution information indicating a volume of the shunt sound as time elapses for each frequency based on the shunt sound information. Sound analysis device.
The output means compares the amount of change of the frequency centroid with the passage of time indicated by the distribution information with the amount of change of the frequency centroid with the passage of time in normal time, and quantifies the degree of intermittence. The shunt sound analysis apparatus according to claim 8, further comprising: means.
The output means includes
Having at least two kinds of the first to fifth digitizing means;
10. The information according to claim 4, wherein each of the continuity levels digitized by the first to fifth digitizing means is determined in an integrated manner, and information indicating the continuity level is output. Shunt sound analyzer.
An acquisition step of acquiring shunt sound information related to the shunt sound from the measurement subject's shunt formation site,
A shunt sound analysis method comprising: an output step of outputting information indicating a degree of audibility of the shunt sound based on the shunt sound information acquired in the acquisition step.
An acquisition step of acquiring shunt sound information related to the shunt sound from the measurement subject's shunt formation site,
A computer program that causes a computer to execute an output step of outputting information indicating the degree of audibility of the shunt sound on the basis of the shunt sound information acquired in the acquisition step.
A recording medium in which the computer program according to claim 12 is recorded.