JP4134943B2 - Sound signal processing method, sound signal processing unit, abnormal sound inspection method, and abnormal sound inspection apparatus - Google Patents

Description

  The present invention relates to a sound signal processing method and a processing unit for attenuating a noise component having a large amplitude and a short duration included in an input sound signal, and particularly to a sound to be inspected in which an inspection object having a sliding portion is generated. The present invention relates to a sound signal processing method and processing unit for attenuating a noise component to be attenuated, a processing unit, an abnormal sound inspection method and an abnormal sound inspection apparatus using a sound signal whose noise component is reduced by the processing method and processing unit.

An abnormal sound inspection is widely performed in various fields by collecting a sound generated by an inspection object and detecting an abnormal sound included in the collected sound to inspect an abnormal state of the inspection object.
In particular, in each air outlet of a car air conditioner, a film shutter that slides along the opening between a position where the air outlet opens and a position where the air outlet closes and selects an air outlet that blows out air-conditioned air. A product having a sliding portion generates abnormal noise when the components slide due to scratches or deposits. Therefore, a product having such a sliding portion is subjected to a frictional noise inspection that detects abnormal noise generated by the sliding portion and determines the quality of a component.

  In the frictional noise inspection method, a frictional sound (inspected sound) that is an abnormal noise generated by the inspection object is detected. This abnormal noise is a continuous frictional sound, and it is possible to evaluate the presence or absence of abnormality by obtaining the product of the sound pressure and the duration (that is, the time integral value of the sound pressure value).

  However, a noise having a large instantaneous sound pressure such as a striking sound has a large product with the sound pressure even if the duration is short, and affects the detection or evaluation of abnormal sounds. Therefore, in order to block external noise coming from the outside, the conventional frictional noise inspection is generally performed in a soundproof box.

  There is no prior art document to be described regarding the present invention. This is because the prior art known to the applicant is not related to the literature known invention.

  However, since a large installation space is required to use a conventional soundproof box, for example, it is not economical to construct in a factory production line.

  In addition, there are moving average filters and median filters as means for smoothing the noise components contained in the sound signal to be inspected. When a noise component that is very large compared to the friction sound that is the sound to be inspected is input, these filters are used. However, the noise component cannot be sufficiently removed. Alternatively, if the number of samples is increased in order to sufficiently remove the noise component, there is a disadvantage that the calculation time increases with an increase in the calculation amount, and the sound component other than the noise component is also adversely affected.

  In view of the above problems, the present invention provides a sound signal processing method and a sound signal processing unit that reduce external noise, which has a large sound pressure level and a short duration, contained in a sound signal that is an inspected sound with a small amount of processing. It is another object of the present invention to provide an abnormal sound inspection method and an abnormal sound inspection apparatus using these.

  In order to achieve the above object, in the present invention, among the sound signals of the input sound to be inspected, the sound signal part signal that is a sound signal having a predetermined sound pressure level or higher and whose duration is not longer than a predetermined time. Reduce the value.

Here, in order to obtain the duration of a sound signal that is equal to or higher than a predetermined sound pressure level, the sound pressure level that is the sound signal portion before the start of the lifetime and the sound signal portion after the end of the lifetime is within the predetermined level. It is necessary to detect a certain sound signal.
However, the input sound signal is an alternating signal whose signal value fluctuates on the positive side and the negative side with respect to zero. Therefore, when the signal value of a certain signal portion is small, the signal portion is a part of a sound signal having a sound pressure within a predetermined sound pressure level, and a sound with the signal portion being equal to or higher than the predetermined sound pressure level. There are two possible cases where the signal value is a portion that is alternating between the plus side and the minus side or vice versa in the alternating signal of the signal.

  Therefore, in order to obtain the duration of the sound signal that is equal to or higher than the predetermined sound pressure level, the signal portion that is detected to be equal to or lower than the signal value threshold corresponding to the predetermined sound pressure level is in any of the above two cases. It is necessary to determine whether it is a signal part.

  Therefore, in the present invention, when a section of a signal portion that is within a signal value threshold (upper limit Vt1, lower limit Vt2) corresponding to the predetermined sound pressure level is shorter than a predetermined length Δt1, the signal portion is determined to have a predetermined sound pressure. Considered as part of a continuous sound signal greater than the level. When the section length of the sound signal portion regarded as a continuous sound is shorter than the predetermined length Δt2, the signal in that section is attenuated.

  That is, in the sound signal processing method according to the first aspect of the present invention, among the input sound signals, the signal value of the sound signal is equal to or greater than a predetermined second threshold value that is equal to or smaller than a predetermined first threshold value and smaller than the first threshold value. Is a section that is not continuous for the first predetermined length or longer and the signal value of the section whose section length is shorter than the second predetermined length is attenuated.

  In the sound signal processing unit according to the second aspect of the present invention, the input sound signal has a signal value of the sound signal equal to or lower than a predetermined first threshold and lower than the predetermined second threshold. A signal in which the signal value is attenuated is output in a section in which the section is not continuous for the first predetermined length or longer and the section length is shorter than the second predetermined length.

Still further, the abnormal sound inspection method according to the third aspect of the present invention is a noise component generated in a section shorter than the second predetermined length included in the sound to be inspected generated by the sound signal processing method according to the present invention. An abnormal sound inspection of the inspection object is performed using a sound signal with reduced noise.
Furthermore, the abnormal sound inspection apparatus according to the fourth aspect of the present invention includes a sound signal processing unit according to the second aspect of the present invention, a sound signal acquisition means for acquiring a sound signal related to the sound to be inspected in which the inspection target is generated, Using the sound signal, which is included in the sound signal acquired by the sound signal acquisition means and is generated by reducing the noise component generated in the section shorter than the second predetermined length by the sound signal processing unit, Perform an inspection.

In addition, the sound signal to be subjected to the abnormal sound inspection is a section in which a section where the signal value is equal to or less than the first threshold and equal to or greater than the second threshold is not continuous for the first predetermined length, and the section length is equal to or greater than the second predetermined length. The sound signals included in the section may be excluded from the abnormal sound inspection.
In this case, in the sound signal processing method according to the first embodiment and the sound signal processing unit according to the second embodiment, a section in which the signal value is equal to or less than the first threshold and equal to or greater than the second threshold is a section that does not continue for the first predetermined length or more. And, instead of reducing the sound signal of the section whose section length is shorter than the second predetermined length, the section where the signal value is equal to or less than the first threshold and equal to or greater than the second threshold is a section that is not continuous for the first predetermined length or more. , A section having a section length equal to or longer than the second predetermined length may be detected, and sound signals included in sections other than the detected section may be attenuated.

  According to the present invention, it is possible to reduce a noise signal included in a signal to be inspected with a remarkably small amount of processing. Further, by using the sound to be inspected in which noise is reduced in this way, it is possible to improve the accuracy of the inspection result of the frictional noise inspection.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an abnormal sound inspection apparatus according to an embodiment.
The abnormal sound inspection apparatus 1 includes an amplifier 11 that amplifies an analog sound signal input by an external microphone 2 that collects a friction sound of an inspection object 3 that is a sound to be inspected into an input signal having a predetermined rating, and an amplifier 11 that amplifies the analog sound signal. The obtained analog sound signal is sampled at a predetermined sampling period Δt, and a digital sound signal (hereinafter simply referred to as “sound signal”) in which signal values at each time ti (i is a natural number) in each sampling period Δi are continuous. And an analog-digital converter 12 for conversion.

  Further, the abnormal sound inspection apparatus 1 is processed by the digital filter 13 which is a sound signal processing unit according to the present invention that reduces or removes noise components from the sound signal converted by the analog-digital converter 12 and the digital filter 13. When the product (time integration value) of the sound pressure level of the frictional sound indicated by the sound signal and the lifetime is large, the determination unit 14 that determines that the sound is abnormal, the display unit 15 that displays the determination result of the determination unit 14, and the determination An alarm device 16 is provided to alert the operator when an abnormal sound is detected by the determination of the device 14. The microphone 2 may be incorporated in the abnormal sound inspection apparatus 1 and may be a part of the abnormal sound inspection apparatus 1.

  FIG. 2 is a block diagram of the digital filter 13 of FIG. 1, which is a sound signal processing unit according to an embodiment of the present invention. The digital filter 13 includes an arithmetic unit 21 having an input terminal for inputting the sound signal converted by the analog-digital converter 12 at the preceding stage and an output terminal for outputting the processed sound signal to the determination unit 14 at the subsequent stage. The computing unit 21 is constituted by a digital signal processor (DSP), for example.

  The data bus 22 of the computing unit 21 is connected to the filter parameter storage unit 23, the original sound storage unit 24, and the work area storage unit 25, and can exchange data with the computing unit 21. In FIG. 2, these storage units are divided and described, but they may be realized as a single storage element.

  Various parameters used by the computing unit 21 for operating the digital filter 13 are stored in the filter parameter storage unit 23, and a first threshold value Vt1, a second threshold value Vt2, a first predetermined length Δt1, and a second predetermined length Δt2 described later. Are also stored in the filter parameter storage unit 23.

  In the original sound storage unit 24, sound signals sequentially input from the analog-digital converter 12 are temporarily stored until they are processed by the digital filter 13 and sequentially output to the determiner 14.

  The work area storage unit 25 stores variables used by the computing unit 21 for its operation. Of the input sound signal, the later-described table 1, table 2, and table 3 used for selecting a portion to be attenuated by the computing unit 21 are also stored in the work area storage unit 25. The calculator 21 and the work area storage unit 25 in which these tables are stored are the first selection means, the second selection means, the third selection means, and the fourth selection of the sound signal processing unit according to the present invention. Make a means.

A sound signal processing method according to an embodiment of the present invention will be described below with reference to FIGS. 3 (A) to (D) and FIGS. 4 (A) to (D).
FIG. 3A is an overall flowchart of the sound signal processing method according to the embodiment of the present invention. The sound signal processing method according to the present invention basically includes a threshold check step S51, a continuity check step S52, a section length check step S53, and a signal attenuation step S54.

In the threshold check step S51, a section of a signal part in which the sound pressure level exceeds a predetermined threshold level is selected from the input audio signal.
In the continuity check step S52, when the section length of the signal portion whose sound pressure level does not exceed the predetermined threshold level is shorter than the predetermined length Δt1, the continuous sound whose sound pressure level exceeds the predetermined threshold level is also detected in this section. It is selected as a part and combined with the section selected in step S51. Thereby, the section of the signal portion related to the continuous sound whose sound pressure level exceeds the predetermined threshold level is selected.

In the section length check step S53, a section in which the section length of the section is shorter than the predetermined length Δt2 is selected from the continuous sound signal portions selected in the continuity check step S52. Thereby, it is possible to select a noise component that is a continuous sound whose sound pressure level exceeds a predetermined threshold level but whose duration is shorter than the time corresponding to the predetermined length Δt2.
In the signal attenuation step S54, the computing unit 21 attenuates or deletes the signal value of the section selected in step S53 among the sound signals stored in the original sound storage unit 24.

The processes in steps S51, S52, and S53 in FIG. FIG. 3B, FIG. 3C, and FIG. 3D show subroutines that show steps S51, S52, and S53 of FIG.
4A is a time chart of the sound signal of the input sound to be inspected, and FIGS. 4B to 4D correspond to the sound to be inspected input in FIG. 4A, respectively. The section selection state performed in steps S51, S52, and S53 in FIG.

  As shown in FIG. 4A, the input sound signal is a value that just exceeds the first threshold value Vt1 at t8, t11, t20, t23, t38, and t41, which are times within each sampling period, and t3 , T6, t14, t17, t26, t29, t32, and t35, the values are just below the first threshold value Vt2. The description will be continued below assuming that Vt1 = 100 and Vt2 = −100.

Also, time t2 and t4, time t4 and t6, time t7 and t9, time t10 and t12, time t13 and t15, time t16 and t18, time t19 and t21, time t22 and t24, time t25 and t27, time t28 and t30, time t31 and t33, time t34 and t36, time t37 and t39, time t40 and t42 are respectively time t3, t5, t6, t8, t11, t14, t17, t20, t23, t26, t29, t32, It is the time within the sampling period before and after t35, t38, and t41.
Each time of the input signal and the signal value at each time are shown in the first column and the second column of Table 1 below.

In the subroutine shown in FIG. 3B corresponding to the threshold check step S51 in FIG. 3A, in step S61, for each time ti, the signal value at that time ti exceeds the first threshold Vt1, or the second threshold Vt2. When it is smaller, the sampling period Δi including the time ti (hereinafter simply referred to as “section Δi”) is selected. The selected section is shown in FIG.
The selection state of the section Δi including each time is stored in a binary data table 1 (hereinafter simply referred to as “table 1”) provided in the work area storage unit 25. The contents of Table 1 are shown in the third and fourth columns of Table 1.
The table 1 is a table for storing the section Δi and the selection state for the section Δi. The selection state is indicated by the state “ON” and the selected state is indicated by OFF (the same applies to other tables described later). To do).

  In the example of FIG. 4A, in the sections Δ8 to Δ11, Δ20 to Δ23, and Δ38 to Δ41, the signal value exceeds the first threshold value Vt1, and the sections Δ3 to Δ5, Δ14 to Δ17, Δ26 to Δ29, and In the section of Δ32 to Δ35, the signal value is lower than the second threshold value Vt2, and these sections are selected.

  In the subroutine shown in FIG. 3C corresponding to the continuity check step S52 in FIG. 3A, in step S71, for each time ti, the signal value at that time ti is equal to or lower than the first threshold Vt1 and equal to or higher than the second threshold Vt2. Yes, a section whose section length is shorter than the predetermined length Δt1 is selected.

  In the example of FIG. 4B, the signal value is not less than the first threshold value Vt1 and not less than the second threshold value Vt2 in the sections Δ6 to Δ7, Δ12 to Δ13, Δ18 to Δ19, Δ24 to Δ25, Δt36 to Δ37, and the section length is predetermined. It is selected because it is shorter than the length Δt1. On the other hand, although the signal value is equal to or less than the first threshold value Vt1 and equal to or greater than the second threshold value Vt2 even in the interval Δ30 to Δ31, it is not selected here because the interval length is longer than the predetermined length Δt1.

Thereafter, in step S72, the sections selected in steps S61 and S71 are combined and selected. The selected state is stored in a binary data table 2 (hereinafter simply referred to as “table 2”) provided in the work area storage unit 25.
The selected state is shown in FIG. 4C, and the contents of Table 2 are shown in the third and fifth columns of Table 1.

  In the subroutine shown in FIG. 3C corresponding to the section length check routine S53 in FIG. 3A, in step S81, a section having a section length shorter than Δt2 is selected from the sections configured in step S72. In the example of FIG. 4C, the section length of the sections Δ3 to Δ29 is longer than Δt2, and the section length of the sections Δ32 to Δ41 is shorter than Δt2. Therefore, only the sections Δ32 to Δ41 are selected. The selected state is stored in a binary data table 3 (hereinafter simply referred to as “table 3”) provided in the work area storage unit 25. The selected state is shown in FIG. 4D, and the contents of Table 3 are shown in the third and sixth columns of Table 1.

  Through steps S61, S71, S72, and S81, a continuous sound whose sound pressure level exceeds a predetermined threshold level but whose duration is shorter than the time corresponding to the predetermined length Δt2 can be selected. Accordingly, a noise component whose duration is shorter than the predetermined length Δt2 by appropriately selecting the predetermined length Δt1 based on the signal frequency of the sound to be inspected and appropriately selecting Δt2 based on the minimum duration assumed for the sound to be inspected. This noise component can be attenuated in the subsequent step S54.

Further, instead of the section length check routine S53 (or step S81), the section length of the section of the continuous sound signal portion selected in the continuity check routine S52 (S71, S72) is equal to or longer than the predetermined length Δt2. Then, the selected state and the selected state are inverted and stored as a table in the work area storage unit 25 (see FIG. 4E), and stored in the original sound storage unit 24 in the subsequent signal attenuation step S54. The signal value of the selected section of the sound signal may be attenuated or deleted.
This is because the frictional sound to be inspected for abnormal noise is included in a section in which the section length of the section of the continuous sound signal portion selected in the continuity check step S52 is equal to or longer than the predetermined length Δt2, and therefore other than this section. This is because, by attenuating the signal for each section, it is possible to attenuate the noise component contained therein.

An alternative embodiment of the sound signal processing method according to the present invention will be described below with reference to FIGS. 5 (A) to 5 (C) and FIGS. 6 (A) to 6 (D).
FIG. 5A is a flowchart of a subroutine according to an alternative embodiment corresponding to the threshold check step S51 shown in FIG. 3A. FIG. 5B is a flowchart of the continuity check step S52 shown in FIG. FIG. 5C is a flowchart of a subroutine according to an alternative embodiment corresponding to the section length check step S53 shown in FIG. 3A.

  6A is a time chart of the sound signal of the input sound to be inspected as in FIG. 4A, and FIGS. 6B to 6D are diagrams for the input sound to be inspected. 5 (A) to 5 (C) show the section selection state performed in the processing shown in the flowchart.

In the threshold value check routine S51 (S91) shown in FIG. 5A, a section of a signal portion whose sound pressure level is within a predetermined threshold level is selected from the input audio signal. That is, for each time ti, when the signal value at that time ti is not less than the first threshold value Vt1 and not more than the second threshold value Vt2, the sampling period (section) Δi including that time ti is selected.
In the example of FIG. 6A, the signal values are the sections in the sections Δ1 to Δ2, Δ6 to Δ7, Δ12 to Δ13, Δ18 to Δ19, Δ24 to Δ25, Δ30 to Δ31, Δ36 to Δ37, and Δ42 to Δ43. 1 threshold value Vt1 or more and 2nd threshold value Vt2 or less, and these sections are selected. The selected section is stored in Table 1. The section selection state is shown in FIG. 6B, and the contents of Table 1 are shown in the third and fourth columns of Table 2.

In the continuity check routine S52 (S101) shown in FIG. 5B, a section whose section length is equal to or longer than the predetermined length Δt1 is selected from the sections selected in the threshold check routine S51. Thereby, the section of the signal part other than the continuous sound that is larger than the predetermined threshold level is selected.
In the example of FIG. 6B, the section lengths of the sections Δ1 to Δ2, Δ30 to Δ31, and Δ42 to Δ43 are longer than Δt1, and these sections Δ32 to Δ41 are selected.
The selected section is stored in Table 2. The section selection state is shown in FIG. 6C, and the contents of Table 2 are shown in the third and fifth columns of Table 2.

  In the section length check routine S53 (S111) shown in FIG. 5C, a section whose section length is shorter than the predetermined length Δt2 is selected from the sections not selected in the continuity check routine S52 (S101). Thereby, it is possible to select a noise component that is a continuous sound whose sound pressure level exceeds a predetermined threshold level but whose duration is shorter than the time corresponding to the predetermined length Δt2.

In the example of FIG. 6C, the sections Δ3 to Δ29 and Δ32 to Δ41 are not selected in the continuity check routine S52 (S101), but the section length of the sections Δ32 to Δ41 is shorter than the predetermined length Δt2. Δ32 to Δ41 are selected.
The selected section is stored in Table 3. The section selection state is shown in FIG. 6D, and the contents of Table 3 are shown in the third and sixth columns of Table 2.

  As described above, also through steps S91, S101, and S111, it is possible to select a continuous sound whose sound pressure level exceeds the predetermined threshold level but whose duration is shorter than the time corresponding to the predetermined length Δt2.

  Further, instead of the section length check routine S53 (or step S111), among the continuous sound signal portions selected in the continuity check routine S52 (S101), the sections not selected in the continuity check routine S52 (S101) Then, after selecting a section whose section length is equal to or longer than the predetermined length Δt2, the selected state and the selected state are inverted and stored as a table in the work area storage unit 25 (see FIG. 6E), and the subsequent signal attenuation routine In S54, the signal value of the selected section of the sound signal stored in the original sound storage unit 24 may be attenuated or deleted.

1 is an overall configuration diagram of an abnormal sound inspection apparatus according to an embodiment of the present invention. It is a block diagram of the digital filter which concerns on the Example of this invention. It is a flowchart of the sound signal processing method which concerns on the Example of this invention. It is explanatory drawing of the sound signal processing method shown in FIG. 4 is a flowchart according to an alternative embodiment of the sound signal processing method shown in FIG. 3. It is explanatory drawing of the sound signal processing method shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Abnormal sound inspection apparatus 3 ... Test object 13 ... Digital filter 21 ... Calculator 23, 24, 25 ... Memory | storage part

Claims (14)

Of the sound signals input, a section having a signal value or first signal value smaller than a predetermined second threshold value from the threshold value exceeds a predetermined first threshold value, above said first threshold value or less and the second threshold value A continuous section obtained by adding a section having a signal value and a section length less than the first predetermined length, and the section length of the continuous section is shorter than the second predetermined length . A sound signal processing method comprising attenuating a signal value. A first step of selecting a section of the sound signal whose signal value exceeds the first threshold and a section of less than the second threshold ;
A second step of selecting a section of the sound signal whose signal value is equal to or smaller than the first threshold and equal to or greater than the second threshold , and whose section length is shorter than the first predetermined length;
A third step of selecting a section having a continuous section length shorter than the second predetermined length among sections obtained by adding the section selected by the second step to the section selected by the first step; ,
The sound signal processing method according to claim 1, wherein the signal value of the section selected by the third step is attenuated among the sound signals. A first step of selecting a section of the sound signal whose signal value is not more than the first threshold and not less than the second threshold ;
A second step of selecting a section whose section length is equal to or greater than the first predetermined length among the sections selected in the first step;
A third step of selecting a section whose section length is shorter than the second predetermined length among sections of the sound signal that are not selected in the second step;
The sound signal processing method according to claim 1, wherein the signal value of the section selected by the third step is attenuated among the sound signals. Among input sound signals, a section having a signal value exceeding a predetermined first threshold value or a signal value less than a predetermined second threshold value smaller than the first threshold value, and not more than the first threshold value and not less than the second threshold value A continuous section obtained by adding a section having a signal value and a section length less than a first predetermined length, and a continuous section having a section length of the second predetermined length or more ,
A sound signal processing method comprising attenuating a signal value of a section other than the detected continuous section of the input sound signal. A first step of selecting a section of the sound signal whose signal value exceeds the first threshold and a section of less than the second threshold ;
A second step of selecting a section of the sound signal whose signal value is equal to or smaller than the first threshold and equal to or greater than the second threshold , and whose section length is shorter than the first predetermined length;
A third step of selecting a section having a continuous section length equal to or longer than the second predetermined length among sections selected by the first step and the section selected by the second step; ,
5. The sound signal processing method according to claim 4, wherein a signal value of a section not selected by the third step is attenuated in the sound signal. A first step of selecting a section of the sound signal whose signal value is not more than the first threshold and not less than the second threshold ;
A second step of selecting a section whose section length is equal to or greater than the first predetermined length among the sections selected in the first step;
A third step of selecting a section whose section length is not less than the second predetermined length among sections of the sound signal that are not selected in the second step;
5. The sound signal processing method according to claim 4, wherein a signal value of a section not selected by the third step is attenuated in the sound signal.   The sound signal processing method according to any one of claims 1 to 6, wherein a noise component generated in at least a section shorter than the second predetermined length is reduced among signal components included in a sound to be inspected generated by an inspection target. An abnormal sound inspection method, wherein an abnormal sound inspection of the inspection object is performed using a sound signal. A section having a signal value exceeding a predetermined first threshold or a signal value less than a predetermined second threshold smaller than the first threshold, and a first predetermined having a signal value equal to or lower than the first threshold and equal to or higher than the second threshold Output a signal obtained by attenuating a signal value of a continuous section which is a continuous section obtained by adding a section length less than the length, and the section length of the continuous section is shorter than the second predetermined length. Sound signal processing unit. A storage unit for storing the sound signal;
First selection means for selecting a section of the sound signal whose signal value exceeds the first threshold and a section of the sound signal less than the second threshold ;
Second selection means for selecting a section of the sound signal whose signal value is equal to or smaller than the first threshold and equal to or greater than the second threshold , and whose section length is shorter than the first predetermined length;
A third selection means for selecting a section having a continuous section length shorter than the second predetermined length among sections selected by the first selection means and a section selected by the second selection means;
Attenuating means for attenuating the signal value of the section selected by the third selecting means among the stored sound signals;
The sound signal processing unit according to claim 8, comprising: A storage unit for storing the sound signal;
First selection means for selecting a section of the sound signal whose signal value is equal to or lower than the first threshold and equal to or higher than the second threshold ;
Of the sections selected by the first selection means, second selection means for selecting a section whose section length is equal to or greater than the first predetermined length;
A third selection means for selecting a section of the sound signal that is not selected by the second selection means and whose section length is shorter than the second predetermined length;
Attenuating means for attenuating the signal value of the section selected by the third selecting means among the stored sound signals;
The sound signal processing unit according to claim 8, comprising: A section having a signal value exceeding a predetermined first threshold or a signal value less than a predetermined second threshold smaller than the first threshold, and a first predetermined having a signal value equal to or lower than the first threshold and equal to or higher than the second threshold A continuous section obtained by adding a section length less than the length, and a continuous section in which the section length of the continuous section is equal to or greater than a second predetermined length ,
A sound signal processing unit that outputs a signal obtained by attenuating signal values in sections other than the detected continuous section among the input sound signals. A storage unit for storing the sound signal;
First selection means for selecting a section of the sound signal whose signal value exceeds the first threshold and a section of the sound signal less than the second threshold ;
Second selection means for selecting a section of the sound signal whose signal value is equal to or smaller than the first threshold and equal to or greater than the second threshold , and whose section length is shorter than the first predetermined length;
A third selecting means for selecting a section having a continuous section length equal to or longer than the second predetermined length among sections obtained by adding the section selected by the second selecting means to the section selected by the first selecting means;
A fourth selection means for selecting a section of the stored sound signal that is not selected by the third selection means;
Attenuating means for attenuating the signal value of the section selected by the fourth selecting means among the stored sound signals;
The sound signal processing unit according to claim 11, comprising: A storage unit for storing the sound signal;
First selection means for selecting a section of the sound signal whose signal value is equal to or lower than the first threshold and equal to or higher than the second threshold ;
Of the sections selected by the first selection means, second selection means for selecting a section whose section length is equal to or greater than the first predetermined length;
A third selection means for selecting a section of the sound signal that is not selected by the second selection means and whose section length is equal to or longer than the second predetermined length;
A fourth selection means for selecting a section of the stored sound signal that is not selected by the third selection means;
Attenuating means for attenuating the signal value of the section selected by the fourth selecting means among the stored sound signals;
The sound signal processing unit according to claim 11, comprising: The sound signal processing unit according to any one of claims 8 to 13,
Sound signal acquisition means for acquiring a sound signal related to the sound to be inspected in which the inspection object is generated,
Using the sound signal obtained by reducing the noise component generated at least in a section shorter than the second predetermined length, among the components included in the sound signal acquired by the sound signal acquiring means, by the sound signal processing unit, An abnormal sound inspection apparatus for performing an abnormal sound inspection on an object.

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