Acoustic diagnostic device and acoustic diagnostic program

Abstract

To provide an acoustic diagnosis device, an acoustic diagnosis method, and an acoustic diagnosis program for acoustically exciting a structure to diagnose the structure in a non-contact manner.SOLUTION: An acoustic diagnosis device has a speaker, a sound receiving unit, a positioning mechanism, an impulse response calculation unit, an intensity calculation unit, an acoustic absorptivity calculation unit, and an acoustic absorptivity change evaluation unit. The speaker emits a sound wave for acoustic excitation toward an object to be diagnosed. The sound receiving unit has first and second microphones that receive the sound wave from the object to be diagnosed. The positioning mechanism determines the position of the sound receiving unit. The impulse response calculation unit calculates impulse responses from the microphones based on sound receiving signals from the microphones. The intensity calculation unit calculates intensity values on a measurement axis passing through the first and second microphones based on the impulse responses. The acoustic absorptivity calculation unit calculates acoustic absorptivity from the intensity values. The acoustic absorptivity change evaluation unit evaluates acoustic characteristics based on a change in the acoustic absorptivity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to an acoustic diagnostic apparatus and an acoustic diagnostic program. [Background technology]

[0002] In buildings and infrastructure structures, deterioration over time can occur in the form of changes in rigidity due to changes in welding or joining conditions of the structure, changes in structural damping characteristics due to peeling of internal coatings such as vibration-damping materials, and changes in strength due to rust, cracks, cavities, etc. in the internal structure. Conventionally, deterioration evaluations have been performed by periodic hammering, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-219138 A [Patent Document 2] Patent No. 6457456 [Patent Document 3] Patent Publication No. 2021-124439 [Patent Document 4] Japanese Patent Application Publication No. 05-118965 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an acoustic diagnostic device and an acoustic diagnostic program for acoustically exciting a diagnosis target such as a structure and diagnosing the same in a non-contact manner. [Means for solving the problem]

[0005] An acoustic diagnostic device according to an embodiment includes a speaker, a sound receiving unit, a positioning mechanism, an impulse response calculation unit, an intensity calculation unit, a sound absorption coefficient calculation unit, and a sound absorption coefficient change evaluation unit. The speaker emits sound waves for acoustic excitation toward a diagnosis object. The sound receiving unit has a first microphone and a second microphone that receive sound waves from the diagnosis object. The positioning mechanism positions the sound receiving unit. The impulse response calculation unit calculates impulse responses of the first microphone and the second microphone based on the sound reception signals of the first microphone and the second microphone. The intensity calculation unit calculates an intensity value on a measurement axis passing through the first microphone and the second microphone based on the impulse responses of the first microphone and the second microphone. The sound absorption coefficient calculation unit calculates the sound absorption coefficient from the intensity value. The sound absorption coefficient change evaluation unit evaluates acoustic characteristics based on the change in sound absorption coefficient to diagnose the diagnosis object. The positioning mechanism positions the first microphone and the second microphone on the speaker axis extending in the direction of sound wave radiation, and holds the sound receiving unit so that it can move along the speaker axis. The sound absorption coefficient calculation unit calculates the sound absorption coefficient using the intensity values ​​of multiple measurement points where the sound receiving unit is positioned by the positioning mechanism. The sound absorption coefficient change evaluation unit diagnoses an increase in the sound absorption coefficient as peeling of the damping material attached to the diagnosis target.

[0007] The acoustic diagnostic program of the embodiment causes a computer having a processor and a storage device to execute the functions of the impulse response calculation unit, the intensity calculation unit, the sound absorption coefficient calculation unit, and the sound absorption coefficient change evaluation unit of the acoustic diagnostic device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of an acoustic diagnostic apparatus according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating hardware of the diagnostic processing unit in FIG. [Diagram 3] FIG. 3 is a diagram showing a Logss signal based on equation (3) with a predetermined value set. [Figure 4] FIG. 4 is a diagram showing a Logss signal obtained by shifting the signal in FIG. 3 by a predetermined amount. [Diagram 5] FIG. 5 is a spectrogram of the Logss signal after the shift shown in FIG. [Figure 6] FIG. 6 is a diagram showing the relationship between time and frequency in the spectrogram of the Logss signal expressed by equations (6) to (8). [Figure 7]FIG. 7 shows a spectrogram when harmonic distortion occurs in the Logss signal that has the spectrogram shown in FIG. [Figure 8] FIG. 8 shows an impulse response obtained by converting the response curve of the Logss signal, which is the spectrogram shown in FIG. 7, using the inverse characteristic of the Logss signal. [Figure 9] FIG. 9 is a diagram showing the results of calculating the occurrence times of the distortion characteristics shown in FIG. 8 based on equation (9). [Figure 10] FIG. 10 is a diagram showing the results of calculation of the occurrence times in the impulse response of the distortion characteristics shown in FIG. 8 based on equation (7). [Figure 11] FIG. 11 is a diagram illustrating an example of an impulse response. [Figure 12] FIG. 12 is an enlarged view of the region RB corresponding to the nonlinear characteristics of the impulse response. [Figure 13] FIG. 13 is a graph showing an example of active intensity measurement. [Figure 14] FIG. 14 is a graph showing an example of reactive intensity measurement. [Figure 15] FIG. 15 is a diagram showing an example of the positional relationship between a first microphone and a second microphone installed at arbitrary positions, an object to be diagnosed, a speaker, and a mirror image sound source. [Figure 16] FIG. 16 is a diagram showing the positional relationship between a first microphone and a second microphone installed on the axis of a speaker, an object to be diagnosed, a speaker, and a mirror image sound source. [Figure 17] FIG. 17 is a flowchart showing the procedure of diagnosis executed by the diagnosis processing unit. [Figure 18] FIG. 18 is a perspective view showing a first structural example of the positioning mechanism. [Figure 19] FIG. 19 is a perspective view of a positioning mechanism for holding a sound receiving unit according to a modified example. [Figure 20] FIG. 20 is a diagram showing the positional relationship of the six microphones in the sound receiving section shown in FIG. [Figure 21] FIG. 21 is a perspective view showing a second structural example of the positioning mechanism. [Figure 22]FIG. 22 is a diagram showing a schematic diagram of the function of the influence elimination plate shown in FIG. [Figure 23] FIG. 23 is a block diagram showing an example of the functional configuration of an acoustic diagnostic apparatus according to the second embodiment. As shown in FIG. [Figure 24] FIG. 24 is a diagram showing the arrangement of the first microphone and the second microphone of the acoustic diagnostic apparatus according to the second embodiment. [Diagram 25] FIG. 25 is a diagram showing a schematic view of a region of interest in a diagnosis object. [Figure 26] FIG. 26 is a diagram showing a modified example of the sound receiving section. [Figure 27] FIG. 27 is a perspective view showing a first structural example of the positioning mechanism as viewed from a first direction. [Figure 28] FIG. 28 is a perspective view showing a first structural example of the positioning mechanism as viewed from a second direction. [Figure 29] FIG. 29 is a perspective view showing a second structural example of the positioning mechanism as viewed from a first direction. [Diagram 30] FIG. 30 is a perspective view showing a second structural example of the positioning mechanism as viewed from a second direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (First embodiment) (Functional configuration) First, the functional configuration of an acoustic diagnostic device according to a first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the functional configuration of an acoustic diagnostic device 1 according to the first embodiment. The acoustic diagnostic device 1 is a device that diagnoses a diagnosis target 90 by using sound waves.

[0011] The acoustic diagnostic device 1 includes an acoustic excitation section 10 , a sound receiving section 20 , a diagnostic processing section 30 , a display 50 , and a positioning mechanism 60 .

[0012] The acoustic excitation unit 10 acoustically excites the diagnosis object 90. Here, acoustically exciting the diagnosis object 90 means emitting sound waves toward the diagnosis object 90 and applying vibration to the diagnosis object 90. For example, the acoustic excitation unit 10 has a speaker 11. The speaker 11 emits sound waves for acoustic excitation toward the diagnosis object 90.

[0013] The speaker 11 radiates sound waves forward from a front face 15. The speaker 11 is disposed so that the front face 15 faces an object to be diagnosed 90. The object to be diagnosed 90 has a plane 91. The speaker 11 is disposed so that the front face 15 of the speaker 11 is parallel to the plane 91 of the object to be diagnosed 90. Hereinafter, an axis passing through the sound source center of the speaker 11 and perpendicular to the front face of the speaker 11 is referred to as a speaker axis 16. In addition, a direction on the speaker axis 16 away from the speaker 11 is referred to as a radiation direction of sound waves for acoustic excitation.

[0014] The sound receiving unit 20 has two or more microphones. Hereinafter, the microphones will be abbreviated to simply "microphones." For example, the sound receiving unit 20 has a first microphone 21 and a second microphone 22. In other words, the sound receiving unit 20 has a microphone group 2122 consisting of the two microphones 21 and 22. The microphones 21 and 22 receive sound waves and output electrical sound receiving signals reflecting sound pressure. The sound waves received by the microphones 21 and 22 include evaluation target sounds including sound waves reflected from the diagnosis object 90 and vibration radiation sounds from the diagnosis object 90, radiation sounds from the speaker 11, and environmental reflection sounds.

[0015] The diagnosis processing unit 30 drives the speaker 11 and diagnoses the diagnosis target 90 based on the audio signals received by the microphones 21 and 22.

[0016] The display 50 displays the results of the diagnosis by the diagnosis processor 30 .

[0017] The diagnosis processing unit 30 includes an impulse response calculation unit 31 , an intensity calculation unit 32 , a sound absorption coefficient calculation unit 33 , a sound absorption coefficient change evaluation unit 34 , and an acoustic excitation signal generation unit 35 .

[0018] The impulse response calculation unit 31 calculates the impulse response of each of the first microphone 21 and the second microphone 22 based on the sound signals received by the first microphone 21 and the second microphone 22 .

[0019] The intensity calculation unit 32 calculates an intensity value on a measurement axis passing through the first microphone 21 and the second microphone 22 based on the impulse responses of the first microphone 21 and the second microphone 22 .

[0020] The sound absorption coefficient calculation unit 33 calculates the sound absorption coefficient from the intensity value. The sound absorption coefficient calculation unit 33 calculates the sound absorption coefficient using the intensity values ​​at a plurality of measurement points.

[0021] The sound absorption coefficient change evaluation unit 34 evaluates the acoustic characteristics based on the change in the sound absorption coefficient to diagnose the diagnosis object 90.

[0022] The acoustic excitation signal generating unit 35 generates an acoustic excitation signal for causing the speaker 11 to emit sound waves for acoustic excitation, and continuously inputs the acoustic excitation signal to the speaker 11. The speaker 11 emits sound waves for acoustic excitation in response to the input of the acoustic excitation signal. The acoustic excitation signal is a TSP (Time Stretched Pulse) signal. For example, the acoustic excitation signal is a Logss (Log Swept Sine) signal, which is a type of TSP signal and is capable of separating nonlinear characteristics.

[0023] The positioning mechanism 60 positions the sound receiving unit 20. The positioning mechanism 60 disposes the first microphone 21 and the second microphone 22 on the speaker axis 16. Furthermore, the positioning mechanism 60 holds the sound receiving unit 20 movably along the speaker axis.

[0024] (Hardware configuration) Next, a description will be given of the hardware configuration of the diagnostic processing unit 30. The diagnostic processing unit 30 is configured with a computer. For example, the diagnostic processing unit 30 is configured with a personal computer, a server computer, or the like.

[0025] Fig. 2 is a block diagram showing an example of a hardware configuration of the diagnostic processing unit 30 according to the embodiment. As shown in Fig. 2, the diagnostic processing unit 30 has an input I / F 41, a CPU 42, a storage device 45, and an output I / F 49. The worker allocation device may further have other peripheral devices in addition to these.

[0026] The input I / F 41, CPU 42, storage device 45, and output I / F 49 are electrically connected to one another via a bus BS, and exchange data and commands via the bus BS.

[0027] The input I / F 41 is a device that receives signals from the outside, converts them into data, and passes them to the CPU 42 and the storage device 45 .

[0028] The output I / F 49 is a device that receives data from the CPU 42 and the storage device 45, converts it into a signal, and outputs it.

[0029] The storage device 45 stores programs and data necessary for processing executed by the CPU 42. The CPU 42 reads out necessary programs and data from the storage device 45 and executes them to perform various types of processing.

[0030] The storage device 45 includes a ROM 46, a main storage device 47, and an auxiliary storage device 48. The main storage device 47 and the auxiliary storage device 48 exchange programs and data with each other.

[0031] The ROM 46 stores a program (BIOS) that controls the CPU 42 at startup.

[0032] The main storage device 47 stores programs and data temporarily required for processing by the CPU 42. For example, the main storage device 47 is configured with a volatile memory such as a RAM (Random Access Memory).

[0033] The auxiliary storage device 48 stores programs and data supplied via an external device or a network, and provides programs and data temporarily required for processing by the CPU 42 to the main storage device 47. For example, the auxiliary storage device 48 is configured with a non-volatile memory such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0034] The CPU 42 is a processor, and is hardware that processes data and instructions. The CPU 42 includes a control device 43 and an arithmetic unit 44.

[0035] The control device 43 controls the input I / F 41 , the arithmetic unit 44 , the storage device 45 and the output I / F 49 .

[0036] The arithmetic unit 44 reads the program and data from the main memory device 47 , executes the program to process the data, and provides the processed data to the main memory device 47 .

[0037] In such a hardware configuration, the CPU 42 and the storage device 45 constitute each part of the diagnostic processing unit 30, namely, the impulse response calculation unit 31, the intensity calculation unit 32, the sound absorption coefficient calculation unit 33, the sound absorption coefficient change evaluation unit 34, and the acoustic excitation signal generation unit 35.

[0038] For example, the CPU 42 loads a program for executing the functions of the diagnostic processing unit 30 from the auxiliary storage device 48 into the main storage device 47, and executes the loaded program to perform the operation of the diagnostic processing unit 30.

[0039] (acoustic excitation signal) As described above, the acoustic excitation signal is a TSP (Time Stretched Pulse) signal. Here, a Logss (Log Swept Sine) signal will be described as an example of a TSP signal. Also, a method for calculating the distortion occurrence time in a Logss signal will be described. For example, the definition equation of the frequency characteristic of a Logss signal is expressed by Equation (1) to Equation (3). Note that N is the Logss signal length, q is an arbitrary real number (J is a multiple of 2), N and q are setting variables, and j is an imaginary number.

[0040]

number

[0041] From equations (1) to (3), the Logss signal is expressed by equation (4). Re represents the real part, and IFFT represents the inverse Fourier transform.

[0042]

number

[0043] A commonly used TSP signal is expressed by the following equation (5): where m is an integer.

[0044]

number

[0045] At this time, the sampling frequency f s 44.1KHz, Logss signal length N is 65536(2 16), and q is 3 / 4, the signal of equation (4) is expressed as shown in FIG. 3. The signal obtained by shifting the signal shown in FIG. 3 by (NJ) / 2 is expressed as shown in FIG. 4. In FIG. 3 and FIG. 4, the vertical axis indicates the level of the voltage applied to the speaker (level adjusted by the connected speaker amplifier), and the horizontal axis indicates time [s]. A Logss signal is generated based on equations (1) to (4), and the signal shifted by (NJ) / 2 is used as the acoustic excitation signal, that is, the input signal to the speaker. Note that the amount of shift is not limited to the above-mentioned value, and for example, as shown in FIG. 4, it is possible to shift the signal from 0 s (1 tap) to 0.1 s (0.1×f s The tap values ​​of tap may be set so that the change in the value near the initial tap is small.

[0046] FIG. 5 shows a spectrogram of the Logss signal after the shift shown in FIG. 4. The vertical axis indicates frequency [Hz], and the horizontal axis indicates time [s]. In the spectrogram shown in FIG. 5, if the vertical and horizontal axes are interchanged, it can be seen that the spectrogram changes like a logarithmic function. That is, the logarithmic frequency is proportional to time, and the frequency is an exponential function of time. Therefore, the relationship between time and frequency in the spectrogram of the Logss signal is expressed by equations (6) to (8). Note that, t offset is the offset time, and shift is the shift amount of the Logss signal described above.

[0047]

number

[0048] Fig. 6 is a graph showing the relationship between time and frequency in the spectrogram of the Logss signal expressed by equations (6) to (8). In Fig. 6, the vertical axis represents frequency [Hz], and the horizontal axis represents time [s].

[0049] At this time, if harmonic distortion of the Logss signal occurs in a state where there is no dynamics characteristic, the graph shown in Fig. 7 will result. Fig. 7 is a spectrogram when harmonic distortion occurs in the Logss signal having the spectrogram shown in Fig. 6. Line L1 is the fundamental wave response curve expressed by equations (6) to (8), line L2 is the second harmonic response curve (first-order distortion response curve), line L3 is the third harmonic response curve (second-order distortion curve), line L4 is the fourth harmonic response curve (third-order distortion curve), and line L5 is the fifth harmonic response curve (fourth-order distortion curve).

[0050] When such harmonic distortion of the Logss signal occurs, the measured response curve is converted by the inverse characteristic of the Logss signal to obtain the graph shown in FIG. 8. FIG. 8 shows an impulse response obtained by converting the response curve of the Logss signal, which is the spectrogram shown in FIG. 7, by the inverse characteristic of the Logss signal. The vertical axis indicates frequency [Hz], and the horizontal axis indicates time [s]. Line L1A, line L2A, line L3A, line L4A, and line L5A are the response curves of lines L1 to L5, respectively. Line L1B is an impulse response corresponding to the fundamental wave response. Line L2B is an impulse response (distortion characteristic of first-order distortion) corresponding to the second harmonic response. Line L3B is an impulse response (distortion characteristic of second-order distortion) corresponding to the third harmonic response. Line L4B is an impulse response (distortion characteristic of third-order distortion) corresponding to the fourth harmonic response. Line L5B is an impulse response (distortion characteristic of fourth-order distortion) corresponding to the fifth harmonic. The impulse response corresponding to the harmonic response calculated in this way appears in the time domain before time 0, that is, in the negative time domain (non-causal direction domain). However, if the distance between the speaker and the microphone is long, the rise time of the linear response is delayed, so that the impulse response corresponding to the harmonic response may occur in the positive time domain. Here, for simplicity, a description is given under the condition of no time delay (no dynamics characteristics). Then, the impulse response corresponding to the harmonic response is separated into distortions of each order in the non-causal direction domain. In this embodiment, by using a Logss signal as an input signal, the impulse response is separated into distortions of each order, and the distortions of each order can be analyzed using the distortion characteristics of the distortions of each order. In a normal TSP, only a linear response can be obtained.

[0051] Moreover, by separating the distortion characteristics as described above, the distortion characteristics of each order are separated into different time domains. At this time, the occurrence time (-t(num)) [s] of the distortion characteristic of each order is expressed by equation (7). Here, num is the order of distortion. For example, when set as described above, the occurrence time of the distortion characteristic shown in FIG. 8 is as shown in FIG. 9. In FIG. 9, the horizontal axis is the distortion order, and the vertical axis is the time [s].

[0052]

number

[0053] Then, from the occurrence time of the distortion characteristic of each order based on the impulse response corresponding to the fundamental wave response, the distortion occurrence time in the derived impulse response is expressed by Equation (8) due to the repetitive nature of the discrete Fourier transform.

[0054]

number

[0055] Here, ta is the delay time of the dynamics characteristics (also called "dead time") and is determined as L / c by the distance L between the speaker and the microphone. Here, c is the speed of sound. Strictly speaking, the delay characteristics of the speaker and the system are also added to ta. ta corresponds to the rise time of the first wave in the causal direction that satisfies the causality rate, which is the opposite direction to the non-causal direction. For example, if the distance L between the speaker and the microphone is sufficiently short and ta can be considered to be 0, with the settings mentioned above, the time at which distortion occurs in the impulse response will be as shown in Figure 10. In Figure 10, the horizontal axis is the distortion order and the vertical axis is time [s].

[0056] (Method of calculating impulse response from TSP signal) The above-mentioned TSP signal is input to a speaker amplifier as a speaker application voltage to drive the speaker 11.

[0057] The microphones 21 and 22 of the sound receiving unit 20 measure, as sound pressure, the direct sound from the speaker 11 accompanying the speaker acoustic excitation, the reflected sound from the diagnosis object 90, and the vibration radiated sound from the diagnosis object 90. In the case of LDV measurement, the vibration velocity of the diagnosis object 90 is measured.

[0058] The impulse response calculation unit 31 calculates an impulse response based on the speaker applied voltage and the microphone acquired sound pressure response. The speaker applied voltage is generated based on a signal in which one TSP (Logss, etc.) signal is arranged a predetermined number of times. The impulse response calculation unit averages the sound pressure changes from the second time onwards in the received signal, with the signal length of the TSP (Logss, etc.) signal being one time. The impulse response calculation unit 31 performs a fast Fourier transform (FFT) on the averaged signal. In the frequency domain, the impulse response calculation unit multiplies the inverse characteristic of the TSP (Logss, etc.) signal in the speaker applied voltage by the signal after FFT processing. The impulse response calculation unit calculates an impulse response by performing an inverse fast Fourier transform (inverse FFT) on the signal after multiplication processing.

[0059] The TSP signal may be filtered by a bandpass filter to match the frequency band that the speaker 11 can output, and used as the speaker applied voltage. This allows the speaker output level (speaker amplifier) ​​to be increased. At this time, the impulse response calculation unit may appropriately correct the influence of filtering by the bandpass filter in the processing in the frequency domain.

[0060] FIG. 11 is a diagram showing an example of an impulse response calculated as described above with the above settings. In FIG. 11, the horizontal axis indicates time [s], and the vertical axis indicates the level of the impulse response. The impulse response shown in FIG. 11 is derived from the microphone response of the sound receiving unit 20 to the speaker acoustic excitation based on the Logss signal. The impulse response is a dynamics characteristic including the speaker characteristic, the acoustic space characteristic, and the acoustic characteristic of the diagnosis target object 90. Therefore, the linear characteristic of the dynamics characteristic appears in the region Ra, and the nonlinear characteristic (distortion characteristic) of the dynamics characteristic appears in the region Rb. The region Ra corresponds to the time (about several seconds) from a time slightly before the time corresponding to the peak value of the impulse response until the occurrence of the residual response (reverberation response) (linear characteristic section). The region Rb is set in a region other than the region Ra according to the distortion occurrence time of FIG. 10.

[0061] Fig. 12 is an enlarged view of a region Rb corresponding to the nonlinear characteristics of the impulse response. In Fig. 12, the horizontal axis indicates time and the vertical axis indicates the level of the impulse response. From Fig. 10, a first-order distortion p1, a second-order distortion p2, and a third-order distortion p3 appear in the order shown in Fig. 12.

[0062] (Intensity calculation method) Next, a method for finding the intensity on a line segment connecting a first microphone 21 and a second microphone 22 that are placed at an interval of a distance d will be described. Here, the first microphone 21 is set as a reference, and the microphones 21, 22 are arranged in the order of the first microphone 21 and the second microphone 22 in the positive direction of the intensity measurement axis.

[0063] During acoustic vibration measurement, if the transfer characteristic obtained through the first microphone 21 is G1(ω) and the transfer characteristic obtained through the second microphone 22 is G2(ω), the active intensity, which represents the flow of sound wave energy on the measurement axis, can be calculated using the following equation (11).

[0064]

number

[0065] Each transfer characteristic is calculated by applying FFT to the impulse response. If the TSP signal is a Logss signal, 0 is inserted after the extracted impulse response and the FFT is applied.

[0066] The measurement range frequency is f corresponding to λ=10d because the particle velocity is approximated using two microphones 21 and 22 spaced apart by a distance d. max Taking into account the measurement accuracy, the upper limit of the measurement frequency is set to approximately =c / (10d).

[0067] Moreover, the reactive intensity, which means the sound pressure squared gradient, is calculated by the following equation (12).

[0068]

number

[0069] As mentioned above, at high frequencies above 1 kHz, if the FFT value is used as is, the intensity characteristic display will be noisy, so the FFT value is converted to a complex number by averaging the gain and phase at a few Hz before and after the frequency, and then the intensity is calculated.

[0070] Figures 13 and 14 show examples of measurements when the microphone distance d is 5 mm. Figure 13 is a graph of an example of active intensity measurement. Figure 14 is a graph of an example of reactive intensity measurement. Note that the FFT values ​​used were obtained by averaging the gain and phase at around 20 Hz and then converting them back to complex numbers.

[0071] (Sound absorption coefficient calculation method) Next, a method for calculating the sound absorption coefficient will be described. First, with reference to Fig. 15, a case where the first microphone 21 and the second microphone 22 are installed at arbitrary positions will be considered. Fig. 15 is a diagram showing an example of the positional relationship between the first microphone 21 and the second microphone 22 installed at arbitrary positions, the diagnosis target 90, the speaker 11, and the mirror image sound source 12. The mirror image sound source 12 is a virtual sound source located in plane symmetry with the speaker 11 with respect to a plane 91 of the diagnosis target 90 that the speaker 11 faces.

[0072] Here, Figure 15 shows an example of a case where the first microphone 21 and the second microphone 22 are installed at arbitrary positions, in which the measurement axis m12 passing through the first microphone 21 and the second microphone 22 is not perpendicular to the plane 91 of the object to be diagnosed 90.

[0073] From the transfer characteristics from the speaker 11 and the mirror image sound source 12, the transfer characteristics to the first microphone 21 and the second microphone 22 installed at arbitrary positions are determined by the following equation (13).

[0074]

number

[0075] Here, q1 is the volume velocity of the speaker 11, q2 is the volume velocity of the mirror sound source 12, and X 11 (ω) is the transfer characteristic from the speaker 11 to the first microphone 21, and X 12 (ω) is the transfer characteristic from the speaker 11 to the second microphone 22, and X 21 (ω) is the transfer characteristic from the mirror sound source 12 to the first microphone 21, X 22 (ω) is the transfer characteristic from the mirror sound source 12 to the second microphone 22.

[0076] Therefore, if there is no environmental reflection, the volume velocity of the speaker 11 and the volume velocity of the mirror image sound source 12 can be easily calculated using the following equation (14).

[0077]

number

[0078] The sound absorption coefficient is also calculated using the following equation (15).

[0079]

number

[0080] However, since environmental reflections occur on floors and walls, it is rare that ideal measurements as described above can be made.

[0081] The intensity on a measurement axis m12 passing through the first microphone 21 and the second microphone 22 installed at arbitrary positions is expressed by the following equation (16), where d is the distance between the microphones.

[0082]

number

[0083] By substituting equation (13) into equation (16), the following equation (17) is obtained.

[0084]

number

[0085] Therefore, if the intensity values ​​are measured at four or more measurement points, the following equation (18) can be solved.

[0086]

number

[0087] However, due to the constraints of the following equation (19), it is necessary to use a nonlinear optimization method (Lagrange constant, quasi-Newton method), and this is not a simple method for measuring sound absorption coefficient.

[0088]

number

[0089] Next, a case where the first microphone 21 and the second microphone 22 are placed on the speaker axis 16 as in this embodiment will be considered with reference to Fig. 16. Fig. 16 is a diagram showing the positional relationship between the first microphone 21 and the second microphone 22 placed on the speaker axis 16, the diagnosis target object 90, the speaker 11, and the mirror image sound source 12.

[0090] In this embodiment, both the first microphone 21 and the second microphone 22 are located on the speaker axis 16 perpendicular to the plane 91 of the diagnosis object 90. That is, the measurement axis m12 is located on the speaker axis 16. In the arrangement relationship of FIG. 16, the following equation (20) is obtained.

[0091]

number

[0092] Here, l1 is the distance between the speaker and the microphone 21, and l2 is the distance between the mirror image sound source and the microphone 22. This gives the following equation (21). In particular, the phases match.

[0093]

number

[0094] Therefore, the following equation (22) is obtained.

[0095]

number

[0096] Therefore, equation (16) can be expressed as the following equation (23).

[0097]

number

[0098] Furthermore, the following equation (24) holds:

[0099]

number

[0100] This can be expressed as the following equation (25):

[0101]

number

[0102] Therefore, when the intensity value is measured at two or more measurement points, the constant multiple value of the volume velocity magnitude can be obtained from the following equations (26) and (27). The subscripts a and b correspond to the two measurement points a and b.

[0103]

number

[0104] The sound absorption coefficient is calculated using the following formula (28). Calculations are performed for each frequency.

[0105]

number

[0106] When measuring intensity values ​​at multiple measurement points on the speaker axis 16, a least squares solution is obtained using a pseudo-inverse matrix, making it possible to reduce the effects of measurement noise. The more measurement points, the better.

[0107] In the case of three-point measurement, for example, the following equation (29) is obtained. Furthermore, when the H matrix shown in the following equation (30) is used, equation (29) can be expressed as the following equation (31).

[0108]

number

[0109] In addition, when the number of measurement points is small, the distance between the measurement points is set sufficiently larger than the microphone distance d so that the row vectors of the H matrix shown in the following equation (30) are not similar. For example, it is set to 2d or more.

[0110] In addition, in order to reduce measurement noise, it is desirable to introduce a relaxation term shown in the following equation (32) or to apply the truncated singular value method.

[0111]

number

[0112] (Diagnostic Procedure) Next, the procedure of diagnosis executed by the diagnosis processor 30 will be described with reference to Fig. 17. Fig. 17 is a flowchart showing the procedure of diagnosis executed by the diagnosis processor 30.

[0113] In step S11, a plurality of measurement points where the sound receiving units 20 are arranged are set.

[0114] In step S12, the positioning mechanism 60 moves and positions the sound receiving unit 20 to one of the measurement points. The positioning mechanism 60 holds the sound receiving unit 20 so that the first microphone 21 and the second microphone 22 are positioned on the speaker axis 16. The positioning mechanism 60 also moves the sound receiving unit 20 along the speaker axis 16 so that the microphones 21 and 22 remain on the speaker axis 16.

[0115] In step S13, the acoustic excitation signal generation unit 35 supplies an acoustic excitation signal to the speaker 11, causing the speaker 11 to emit sound waves for acoustic excitation. The impulse response calculation unit 31 receives sound signals from each of the microphones 21 and 22, and calculates impulse responses of each of the microphones 21 and 22. The intensity calculation unit 32 calculates intensity values ​​on a measurement axis passing through the microphones 21 and 22, based on the impulse responses of the microphones 21 and 22.

[0116] In step S14, if there is a measurement point where the intensity value has not been measured (Yes in S14), the processes of steps S12 and S13 are repeated. If there is no measurement point where the intensity value has not been measured (No in S14), the process proceeds to step S15.

[0117] In step S15, the sound absorption coefficient calculation unit 33 calculates the sound absorption coefficient using the intensity values ​​at the multiple measurement points.

[0118] In step S16, the sound absorption coefficient change evaluation unit 34 evaluates the acoustic characteristics based on the change in the sound absorption coefficient to diagnose the diagnosis object.

[0119] (Diagnostic Method) Next, a description will be given of the diagnostic methods executed by the sound absorption coefficient change evaluation unit 34. Three diagnostic methods will be described here.

[0120] The first diagnostic method is a commonly used method for deterioration diagnosis, and involves comparison with a baseline. In this method, sound absorption coefficient measurements are carried out in advance when a failure mode (weakened joint strength, welding defects, cracks, or cavities) occurs, and an allowable sound absorption coefficient baseline is measured. The measured sound absorption coefficient is compared with the sound absorption coefficient baseline to determine whether it is moving into the danger zone. For example, if the measured sound absorption coefficient exceeds the sound absorption coefficient baseline, it is determined to be abnormal. The horizontal axis is frequency, and the measured sound absorption coefficient and the sound absorption coefficient baseline are plotted to determine deterioration.

[0121] The second diagnostic method is to diagnose the progression of deterioration due to aging, and by monitoring changes over time, it is possible to determine whether the measured sound absorption coefficient is increasing or decreasing, and to determine whether there is an abnormality. The horizontal axis is frequency, and the measured sound absorption coefficient is plotted to capture the tendency of changes in the sound absorption coefficient over time.

[0122] The third diagnostic method is a method of diagnosing the peeling of a damping material attached to a diagnosis target 90, and is a judgment method that utilizes the fact that the diagnosis target 90, such as a plate material (surface material), obtains sound absorption characteristics by vibrating. Generally, when the damping material peels off, the plate material becomes vibratory and the sound absorption characteristics increase. Peeling of the damping material is judged by capturing the tendency of the sound absorption characteristics to increase from the measured sound absorption coefficient.

[0123] (First structural example of positioning mechanism 60) Next, a first structural example of the positioning mechanism 60 will be described with reference to Fig. 18. Fig. 18 is a perspective view showing the first structural example of the positioning mechanism 60, that is, a positioning mechanism 60A.

[0124] The positioning mechanism 60A in FIG. 18 has a frame 61 that holds the speaker 11 and a slider 63 that holds the sound receiving unit 20.

[0125] The frame 61 has four straight pillars 61a and cross bars 61b connecting the pillars 61a. The four pillars 61a extend parallel to one another. The cross bars 61b are fixed to the speaker 11. Each pillar 61a extends parallel to the speaker axis 16 of the speaker 11. In other words, the speaker 11 is attached to the cross bars 61b so that the speaker axis 16 is parallel to the pillars 61a.

[0126] The slider 63 is movable along the support pillars 61a of the frame 61. The slider 63 is T-shaped and has a base 63a extending between the two support pillars 61a and an arm 63b extending from the base 63a. Both ends of the base 63a are connected to the two support pillars 61a via, for example, linear guides. The arm 63b holds the sound receiving unit 20 so that both the first microphone 21 and the second microphone 22 are located on the speaker axis 16.

[0127] (Modification of the sound receiving section 20) Next, a modified example of the sound receiving unit 20 will be described with reference to Figures 19 and 20. Figure 19 is a perspective view of a positioning mechanism 60A that holds the modified example of the sound receiving unit 20, that is, the sound receiving unit 20A.

[0128] 19 has a line array microphone configuration, and has six microphones 21, 22, 23, 24, 25, and 26 arranged in a straight line. All of the six microphones 21 to 26 are disposed on the speaker axis 16.

[0129] 20 is a diagram showing an example of the positional relationship of six microphones 21 to 26 of sound receiving unit 20A. The six microphones 21 to 26 are divided into three microphone groups. That is, sound receiving unit 20A has microphone group 2122 consisting of two microphones 21 and 22, microphone group 2324 consisting of two microphones 23 and 24, and microphone group 2526 consisting of two microphones 25 and 26.

[0130] The microphone spacing between each of the microphone groups 2122, 2324, and 2526 is d. The spacing a between the microphone groups 2122 and 2324 is preferably 2d or more. The spacing b between the microphone groups 2324 and 2526 is preferably 2d or more.

[0131] By using the sound receiving unit 20A, it is possible to measure the intensity at three measurement points simultaneously, which reduces the measurement time.

[0132] (Second structural example of positioning mechanism 60) Next, a second structural example of the positioning mechanism 60 will be described with reference to Fig. 21 and Fig. 22. Fig. 21 is a perspective view showing the second structural example of the positioning mechanism 60, i.e., a positioning mechanism 60B. Fig. 22 is a diagram showing the function of the influence excluding plate 65.

[0133] The positioning mechanism 60B has an influence elimination plate 65 in addition to the configuration of the positioning mechanism 60A. The influence elimination plate 65 is supported by four supports 61a of the frame 61 so as to be movable along the supports 61a. The influence elimination plate 65 has a circular opening 65a in the center, centered on the speaker axis 16.

[0134] 22, the influence elimination plate 65 blocks the reflected sound from structures 95 such as walls and floors. In the acoustic diagnostic device 1 of this embodiment, the influence of environmental reflection can be significantly reduced due to the intensity measurement, and further reduced by using the positioning mechanism 60B.

[0135] As can be seen from the above explanation, the acoustic diagnostic device 1 of this embodiment does not analyze the actual operating sound from the diagnosis object 90, but acoustically vibrates the diagnosis object 90, analyzes the sound waves emitted from the diagnosis object 90, obtains acoustic characteristic information in the analysis specified frequency band, and can determine deterioration.

[0136] Second embodiment (Functional configuration) The functional configuration of an acoustic diagnostic device according to the second embodiment will be described with reference to Fig. 23. Fig. 23 is a block diagram showing an example of the functional configuration of an acoustic diagnostic device 2 according to the second embodiment. In Fig. 23, components with the same reference symbols as those shown in Fig. 1 are similar components, and detailed descriptions thereof will be omitted. The following description will focus on the differences. In other words, the parts not mentioned in the following description are the same as those in the first embodiment.

[0137] Compared to the acoustic diagnostic device 1 of the first embodiment, the acoustic diagnostic device 2 of the second embodiment differs in the arrangement of the first microphone 21 and the second microphone 22 of the sound receiving unit 20, has a diagnostic processing unit 30A instead of the diagnostic processing unit 30, and has a positioning mechanism 70 instead of the positioning mechanism 60.

[0138] The diagnosis processing unit 30A has an impulse response calculation unit 31, an intensity calculation unit 32, a sound absorption coefficient calculation unit 33, a sound absorption coefficient change evaluation unit , an acoustic excitation signal generation unit , and an intensity evaluation unit .

[0139] The intensity evaluation unit 36 ​​evaluates the acoustic characteristics based on the change in intensity to diagnose the diagnosis object 90.

[0140] (Placement of microphones 21 and 22) Next, the arrangement of the first microphone 21 and the second microphone 22 will be described with reference to Fig. 24. Fig. 24 is a diagram showing the arrangement of the first microphone 21 and the second microphone 22 of the acoustic diagnostic device 2 according to the second embodiment.

[0141] In this embodiment, the positioning mechanism 70 positions the sound receiving unit 20 so that a measurement axis m12 passing through the first microphone 21 and the second microphone 22 passes through the sound source center of the mirror image sound source 12, the positive direction of the measurement axis m12 faces the mirror image sound source 12, and is perpendicular to the line segment connecting the sound source center of the speaker 11 and the first microphone 21. Furthermore, the positioning mechanism 70 holds the sound receiving unit 20 rotatably around the speaker axis 16.

[0142] 24, the intensity measurement axis m12 is perpendicular to the line segment connecting the sound source center of the speaker 11 and the microphone 21. Therefore, the energy flow from the speaker 11 is not reflected in the measured intensity on the measurement axis m12 in principle, and the energy flow from only the mirror image sound source 12 is obtained. In other words, the intensity on the measurement axis m12 is expressed by the following equation (33).

[0143]

number

[0144] Since the intensity is a vector quantity with a direction, the influence of environmental reflection can be reduced. Furthermore, since the measured intensity represents the energy from the mirror image sound source 12, it is possible to evaluate the deterioration of the diagnostic object 90 by monitoring the change in characteristics.

[0145] In addition, when a signal called a Logss signal among the TSP signals is used as the acoustic excitation signal, the distortion characteristic, which is a nonlinear characteristic, can also be separated and acquired. In addition to the intensity evaluation of the linear characteristic, the intensity of the separated and extracted distortion characteristic may be evaluated to determine the deterioration. The distortion characteristic generated by the acoustic excitation of the diagnosis object 90 is a nonlinear characteristic represented by the "chatter vibration" of the diagnosis object 90, and is useful for determining the deterioration of the support member.

[0146] (Focus Range) Specific installation positions of the microphones 21 and 22 and the focus range of the diagnosis object 90 are shown below.

[0147] If the distance between the speaker 11 and the diagnosis object 90 is L and the measurement angle relating to the focus is θ, the installation coordinates of the microphone 21 are expressed by the following equation (34).

[0148]

number

[0149] The microphone 22 is placed on the measurement axis at a distance d from the microphone 21. Furthermore, regarding the x coordinate of the microphone 21, the following equation (35) holds.

[0150]

number

[0151] As a result, θ is set in a range that satisfies formula (36), in other words, in a range that satisfies formula (37). That is, θ is set in the range of 45 degrees<θ<90 degrees.

[0152]

number

[0153] Here, the distance between the intersection of the measurement axis m12 and the diagnosis object 90, and the speaker axis 16 is expressed by the following equation (38).

[0154]

number

[0155] This distance becomes the measurement focus. In other words, by decreasing L or increasing θ, the region of interest on the diagnosis object 90 is narrowed, and the measurement resolution is improved. Conversely, by increasing L or decreasing θ, the region of interest on the diagnosis object 90 is widened, and the traverse measurement speed is increased.

[0156] (Area of ​​interest) Next, a region of interest in the diagnosis object 90 will be described with reference to Fig. 25. Fig. 25 is a diagram showing a schematic view of a region of interest in the diagnosis object 90.

[0157] The region of interest is an area within a circumference C1 obtained by rotating the two microphones 21, 22 around the speaker axis 16. The focus region is an area within a circumference C2 formed on the plane 91 of the diagnosis object 90 by the intersection of the plane 91 of the diagnosis object 90 and the measurement axis m12 through rotation. Intensity is measured at several measurement points on the circumference C1, and the average value is taken as the measured intensity value. The number of measurement points is at least three points at intervals of 120 degrees. In this way, by measuring the intensity at multiple measurement points, the average reflectance within the region of interest can be measured. Furthermore, the averaging process can further reduce the influence of environmental reflection than a single intensity measurement.

[0158] (Diagnostic Method) Next, a description will be given of the diagnostic methods executed by the intensity evaluation unit 36. Three diagnostic methods will be described here.

[0159] The first diagnostic method is a commonly used method for deterioration diagnosis, and involves comparison with a baseline. In this method, intensity measurements are performed in advance when a failure mode (reduced bonding strength, welding defects, cracking, or cavity occurrence) occurs, and an intensity baseline within an allowable range is measured. The measured intensity value in the direction of the mirror sound source 12 is compared with the intensity baseline to determine whether it has moved to the danger line. For example, if the measured intensity value in the direction of the mirror sound source 12 exceeds the intensity baseline, it is determined to be abnormal. The horizontal axis is frequency, and the measured intensity value and the intensity baseline are plotted to determine deterioration.

[0160] The second diagnostic method is to diagnose the progression of deterioration due to aging, and by monitoring time-series changes, detect whether the measured intensity is tending to increase or decrease and determine whether there is an abnormality. The horizontal axis is frequency, and the measured intensity values ​​in the direction of the mirror sound source 12 are plotted to capture the tendency of changes in the intensity values ​​over time.

[0161] The third diagnostic technique is a diagnosis of peeling of a damping material attached to a diagnosis target 90, and is a judgment method that utilizes the fact that the diagnosis target 90, such as a plate material (surface material), obtains sound absorbing characteristics by vibrating. Generally, when the damping material peels off, the plate material becomes vibratory, the sound absorbing characteristics increase, and the active intensity value where the positive direction of the measurement axis faces the diagnosis target 90 increases. Peeling of the damping material is judged by capturing the tendency of the intensity value to increase from the measured intensity value in the direction of the mirror image sound source 12.

[0162] (Sound absorption coefficient measurement) Next, a modified example of the sound receiving unit 20 and sound absorption coefficient measurement will be described with reference to Fig. 26. Fig. 26 is a diagram showing a modified example of the sound receiving unit 20, that is, a sound receiving unit 20B.

[0163] The sound receiving unit 20B has a third microphone 23 in addition to the first microphone 21 and the second microphone 22. As described above, the intensity measurement axis m12 passing through the first microphone 21 and the second microphone 22 is oriented toward the sound source center of the mirror image sound source 12.

[0164] The third microphone 23 is placed on a line segment connecting the first microphone 21 and the sound source center of the speaker 11. The third microphone 23 is closer to the speaker 11 than the first microphone 21 and is a distance d away from the first microphone 21. The intensity on a measurement axis m13 passing through the first microphone 21 and the third microphone 23 will be considered. The measurement axis m13 is oriented toward the sound source center of the speaker 11.

[0165] Since the measurement axis m13 passing through the first microphone 21 and the third microphone 23 is perpendicular to the line segment connecting the sound source center of the mirror image sound source 12 and the first microphone 21, the energy flow from the mirror image sound source 12 is not reflected in the measured intensity on the measurement axis m13 in principle, and the energy flow from only the speaker 11 is obtained. In other words, the intensity I 13 , i.e., the intensity I on the measurement axis m13 13 is expressed by the following equation (39).

[0166]

number

[0167] In addition, the intensity I of the 12 directions of the mirror image sound source 12 , i.e., the intensity I on the measurement axis m12 12 is expressed by the following equation (40).

[0168]

number

[0169] Furthermore, the following equation (41) holds:

[0170]

number

[0171] From this, the sound absorption coefficient is calculated using the following equation (42).

[0172]

number

[0173] That is, the three microphones 21, 22, and 23 are rotated around the speaker axis 16, and measurements are taken at multiple measurement points, and the intensity I in the direction of the speaker 11 is obtained. 13 and the intensity of 12 directions of the mirror sound source I 12 The sound absorption coefficient can be measured by calculating (average value) and using formula (39), formula (40), and formula (41). Alternatively, the sound absorption coefficient may be calculated at each measurement point according to formulas (39) to (42), and the results of the sound absorption coefficients at each measurement point may be averaged to calculate the sound absorption coefficient.

[0174] That is, for the sound receiving unit 20B, the diagnosis processing unit 30A performs the following processes. The impulse response calculation unit 31 calculates the impulse response of the third microphone 23 based on the sound receiving signal of the third microphone 23. The intensity calculation unit 32 calculates the intensity value on the measurement axis m13 passing through the first microphone 21 and the third microphone 23 based on the impulse responses of the first microphone 21 and the third microphone 23. The sound absorption coefficient calculation unit 33 calculates the sound absorption coefficient using the intensity value on the measurement axis m13. The sound absorption coefficient change evaluation unit 34 evaluates the acoustic characteristics based on the change in the sound absorption coefficient and diagnoses the diagnosis object 90.

[0175] (First structural example of positioning mechanism 70) Next, a first structural example of the positioning mechanism 70 will be described with reference to Fig. 27 and Fig. 28. Fig. 27 and Fig. 28 are perspective views showing the first structural example of the positioning mechanism 70, i.e., positioning mechanism 70A. Fig. 27 is a perspective view of the positioning mechanism 70A seen from a first direction, and Fig. 28 is a perspective view of the positioning mechanism 70A seen from a second direction different from the first direction.

[0176] The positioning mechanism 70A includes a base 71, an arm 73, a slider 74, an arm 75, and a holder 77.

[0177] The base 71 is fixed to the speaker 11. The arm 73 is L-shaped and has a first arm portion 73a and a second arm portion 73b that are linear and perpendicular to each other. An end of the first arm portion 73a is rotatably connected to the base 71 via a shaft 72. The central axis of the shaft 72 coincides with the speaker axis 16 of the speaker 11.

[0178] The slider 74 is linear and connected to the second arm portion 73b of the arm 73 so as to be linearly movable along the second arm portion 73b. The arm 75 is linear. An end of the arm 75 is rotatably connected to an end of the slider 74 via a shaft 76. The holder 77 is connected to the arm 75 so as to be linearly movable along the arm 75. The holder 77 holds the microphones 21 and 22 and the sound receiving unit 20 having the microphones 21, 22, and 23 (microphone 23 is not shown).

[0179] In this positioning mechanism 70, the microphones 21 and 22 can be moved parallel to the speaker axis 16 of the speaker 11 by moving the slider 74 along the second arm portion 73b of the arm 73. In addition, the direction of the measurement axis m12 passing through the first microphone 21 and the second microphone 22 can be changed by rotating the arm 75 around the shaft 76. Furthermore, the distance from the speaker axis 16 of the speaker 11 to the microphones 21 and 22 can be changed by moving the holder 77 along the arm 75. This allows the sound receiving unit 20 to be positioned in the positional relationship shown in FIG. 24.

[0180] Furthermore, by rotating the arm 73 around the shaft 72, the angular position of the sound receiving unit 20, i.e., the microphones 21 and 22, around the speaker axis 16 of the speaker 11 can be changed. This allows the sound receiving unit 20, i.e., the microphones 21 and 22, to move on a circumference C1 centered on the speaker axis 16, as shown in Fig. 25. This allows the intensity to be measured at multiple measurement points.

[0181] (Second structural example of positioning mechanism 70) Next, a second structural example of the positioning mechanism 70 will be described with reference to Figures 29 and 30. Figures 29 and 30 are perspective views showing the second structural example of the positioning mechanism 70, i.e., positioning mechanism 70B. Figure 29 is a perspective view of the positioning mechanism 70B seen from a first direction, and Figure 30 is a perspective view of the positioning mechanism 70B seen from a second direction different from the first direction. In Figures 29 and 30, members with the same reference numerals as those shown in Figures 27 and 28 are similar members, and detailed descriptions thereof will be omitted.

[0182] The positioning mechanism 70B has three sets of an arm 73, a slider 74, an arm 75, and a holder 77. The configuration of each set of the arm 73, the slider 74, the arm 75, and the holder 77 is similar to that of the first structural example of the positioning mechanism 70, that is, the positioning mechanism 70A.

[0183] The three arms 73 are integrated at intervals of 120 degrees around the center of the shaft 72. That is, the three integrated arms 73 are rotatably connected to the base 71 via the shaft 72.

[0184] In the acoustic diagnostic device 2 using the positioning mechanism 70B, the three sound receiving units 20 are arranged on the circumference C1, so that the intensity at multiple measurement points can be measured simultaneously without rotating the sound receiving units 20.

[0185] As can be seen from the above explanation, the acoustic diagnostic device 2 of this embodiment does not analyze the actual operating sound from the diagnosis object 90, but acoustically vibrates the diagnosis object 90, analyzes the sound waves emitted from the diagnosis object 90, obtains acoustic characteristic information in the analysis specified frequency band, and can determine deterioration.

[0186] According to these embodiments, it is possible to provide an acoustic diagnostic device that performs a non-contact diagnosis by acoustically vibrating an object to be diagnosed.

[0187] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0188] 1,2...acoustic diagnostic device, 10...acoustic excitation unit, 11...speaker, 12...mirror image sound source, 15...front, 16...speaker axis, 20,20A,20B...sound receiving unit, 21,22,23,24,25,26...microphone, 30,30A...diagnosis processing unit, 31...impulse response calculation unit, 32...intensity calculation unit, 33...sound absorption coefficient calculation unit, 34...sound absorption coefficient change evaluation unit, 35...acoustic excitation signal generation unit, 36...intensity evaluation unit, 42...CPU, 43...control unit, 44...arithmetic unit, 45...storage unit, 46...ROM, 47...main storage unit, 48 ...auxiliary storage device, 50...display, 60, 60A, 60B...positioning mechanism, 61...frame, 61a...support, 61b...crossbar, 63...slider, 63a...base, 63b...arm, 65...influence exclusion plate, 65a...opening, 70, 70A, 70B...positioning mechanism, 71...base, 72...shaft, 73...arm, 73a...arm portion, 73b...arm portion, 74...slider, 75...arm, 76...shaft, 77...holder, 90...diagnosis target, 91...plane, 95...structure, 2122, 2324, 2526...microphone group.

Claims

1. A speaker that emits sound waves for acoustic excitation toward the diagnostic object; a sound receiving unit having a first microphone and a second microphone for receiving sound waves from the diagnosis object; A positioning mechanism for positioning the sound receiving unit; an impulse response calculation unit that calculates impulse responses of the first microphone and the second microphone based on the sound signals received by the first microphone and the second microphone; an intensity calculation unit that calculates a first intensity value on a measurement axis passing through the first microphone and the second microphone based on the impulse responses of the first microphone and the second microphone; a sound absorption coefficient calculation unit that calculates a first sound absorption coefficient from the first intensity value; a sound absorption coefficient change evaluation unit that evaluates acoustic characteristics based on the change in the first sound absorption coefficient to diagnose the diagnosis object, the positioning mechanism disposes the first microphone and the second microphone on a speaker axis extending in a radiation direction of the sound wave, and holds the sound receiving unit movably along the speaker axis; The sound absorption coefficient calculation unit calculates the sound absorption coefficient using the intensity values ​​of a plurality of measurement points at which the sound receiving unit is placed by the positioning mechanism, The sound absorption coefficient change evaluation unit diagnoses that the vibration-damping material attached to the diagnosis object has peeled off when the sound absorption coefficient has increased. Acoustic diagnostic equipment.

2. A speaker that emits sound waves for acoustic excitation toward the diagnostic object; a sound receiving unit having a first microphone and a second microphone for receiving sound waves from the diagnosis object; A positioning mechanism for positioning the sound receiving unit; an impulse response calculation unit that calculates impulse responses of the first microphone and the second microphone based on the sound signals received by the first microphone and the second microphone; an intensity calculation unit that calculates a first intensity value on a measurement axis passing through the first microphone and the second microphone based on the impulse responses of the first microphone and the second microphone; a sound absorption coefficient calculation unit that calculates a first sound absorption coefficient from the first intensity value; a sound absorption coefficient change evaluation unit that evaluates acoustic characteristics based on the change in the first sound absorption coefficient to diagnose the diagnosis object; the positioning mechanism disposes the first microphone and the second microphone on a speaker axis extending in a radiation direction of the sound wave, and holds the sound receiving unit movably along the speaker axis; The sound absorption coefficient calculation unit calculates the sound absorption coefficient using the intensity values ​​of a plurality of measurement points at which the sound receiving unit is placed by the positioning mechanism, The sound absorption coefficient change evaluation unit compares a sound absorption coefficient baseline of a deteriorated state, which is determined by measuring in advance when a failure mode occurs, with the first sound absorption coefficient, and diagnoses deterioration of the diagnosis object. Acoustic diagnostic equipment.

3. A speaker that emits sound waves for acoustic excitation toward the diagnostic object; a sound receiving unit having a first microphone and a second microphone for receiving sound waves from the diagnosis object; A positioning mechanism for positioning the sound receiving unit; an impulse response calculation unit that calculates impulse responses of the first microphone and the second microphone based on the sound signals received by the first microphone and the second microphone; an intensity calculation unit that calculates a first intensity value on a measurement axis passing through the first microphone and the second microphone based on the impulse responses of the first microphone and the second microphone; a sound absorption coefficient calculation unit that calculates a first sound absorption coefficient from the first intensity value; a sound absorption coefficient change evaluation unit that evaluates acoustic characteristics based on the change in the first sound absorption coefficient to diagnose the diagnosis object, The positioning mechanism disposes the sound receiving unit so that the measurement axis passing through the first microphone and the second microphone passes through a sound source center of a mirror image sound source located in plane symmetry with the speaker with respect to a plane of the diagnosis object to which the speaker faces, and is perpendicular to a line segment connecting the sound source center of the speaker and the first microphone, and holds the sound receiving unit rotatably around the speaker axis of the speaker. Acoustic diagnostic equipment.

4. An intensity evaluation unit that evaluates a change in the first intensity value to diagnose deterioration of the diagnosis object. The acoustic diagnostic device according to claim 3 .

5. The positive direction of the measurement axis is directed toward the mirror image sound source, and the intensity evaluation unit diagnoses peeling of a vibration-damping material attached to the diagnosis object when the first intensity value increases. The acoustic diagnostic device according to claim 4.

6. the sound receiving unit further includes a third microphone that receives sound waves from the speaker, the third microphone being disposed on a line segment connecting the sound source center of the speaker and the first microphone; The impulse response calculation unit calculates an impulse response of the third microphone based on the sound signal received by the third microphone; the intensity calculation unit calculates a second intensity value on a measurement axis passing through the first microphone and the third microphone based on the impulse responses of the first microphone and the third microphone; The sound absorption coefficient calculation unit calculates a second sound absorption coefficient by using the second intensity value, the sound absorption coefficient change evaluation unit evaluates an acoustic characteristic based on the change in the second sound absorption coefficient to diagnose the diagnosis object. The acoustic diagnostic device according to claim 3 .

7. The sound absorption coefficient change evaluation unit diagnoses that the vibration-damping material attached to the diagnosis object has peeled off when the sound absorption coefficient has increased. The acoustic diagnostic device according to claim 6.

8. The sound absorption coefficient change evaluation unit compares a sound absorption coefficient baseline of a deteriorated state, which is determined by measuring in advance when a failure mode occurs, with the first sound absorption coefficient, and diagnoses deterioration of the diagnosis object. The acoustic diagnostic device according to claim 6.

9. A computer having a processor and a memory device, 2. A device for causing a computer to execute the functions of the impulse response calculation unit, the intensity calculation unit, the sound absorption coefficient calculation unit, and the sound absorption coefficient change evaluation unit according to claim 1. Acoustic diagnostic program.

10. A computer having a processor and a memory device, 4. A sound absorption coefficient change evaluation unit that performs the functions of the impulse response calculation unit, the intensity calculation unit, the sound absorption coefficient calculation unit, and the sound absorption coefficient change evaluation unit according to claim 3. Acoustic diagnostic program.

11. A speaker that emits sound waves for acoustic excitation toward the diagnostic object; a sound receiving unit having a first microphone and a second microphone for receiving sound waves from the diagnosis object; A positioning mechanism for positioning the sound receiving unit; an impulse response calculation unit that calculates impulse responses of the first microphone and the second microphone based on the sound signals received by the first microphone and the second microphone; an intensity calculation unit that calculates a first intensity value on a measurement axis passing through the first microphone and the second microphone based on the impulse responses of the first microphone and the second microphone; a sound absorption coefficient calculation unit that calculates a first sound absorption coefficient from the first intensity value; a sound absorption coefficient change evaluation unit that evaluates acoustic characteristics based on the change in the first sound absorption coefficient to diagnose the diagnosis object, the positioning mechanism disposes the first microphone and the second microphone on a speaker axis extending in a radiation direction of the sound wave, and holds the sound receiving unit movably along the speaker axis; The sound absorption coefficient calculation unit calculates the first sound absorption coefficient α(ω) using the first intensity values ​​I a (ω) and I b (ω) at the first and second measurement points where the sound receiving unit is placed by the positioning mechanism, using the following formulas (1) and (2): [0010] Here, q1(ω) is the volume velocity of the speaker, q2(ω) is the volume velocity of a mirror image sound source which is a virtual sound source located in plane symmetry with the speaker with respect to the plane of the object to be diagnosed which the speaker faces, d is the distance between the first microphone and the second microphone, l a1(ω) and l b1(ω) are the distances between the speaker and the first microphone at the first and second measurement points, respectively, and l a2(ω) and l b2(ω) are the distances between the mirror image sound source and the second microphone at the first and second measurement points, respectively. Acoustic diagnostic equipment.

12. A speaker that emits sound waves for acoustic excitation toward the diagnostic object; a sound receiving unit having a first microphone and a second microphone for receiving sound waves from the diagnosis object; A positioning mechanism for positioning the sound receiving unit; an impulse response calculation unit that calculates impulse responses of the first microphone and the second microphone based on the sound signals received by the first microphone and the second microphone; an intensity calculation unit that calculates a first intensity value on a measurement axis passing through the first microphone and the second microphone based on the impulse responses of the first microphone and the second microphone; a sound absorption coefficient calculation unit that calculates a first sound absorption coefficient from the first intensity value; a sound absorption coefficient change evaluation unit that evaluates acoustic characteristics based on the change in the first sound absorption coefficient to diagnose the diagnosis object, the positioning mechanism disposes the first microphone and the second microphone on a speaker axis extending in a radiation direction of the sound wave, and holds the sound receiving unit movably along the speaker axis; The sound absorption coefficient calculation unit calculates the first sound absorption coefficient α(ω) using the first intensity values ​​I a (ω), I b (ω), and I c (ω) at the first, second, and third measurement points where the sound receiving unit is placed by the positioning mechanism, using the following formulas (3), (4), and (5): [0025] Here, q1(ω) is the volume velocity of the speaker, q2(ω) is the volume velocity of a mirror image sound source which is a virtual sound source located in plane symmetry with the speaker with respect to the plane of the object to be diagnosed which the speaker faces, d is the distance between the first microphone and the second microphone, l a1(ω), l b1(ω), l c1(ω) are the distances between the speaker and the first microphone at the first, second and third measurement points, respectively, and l a2(ω), l b2(ω), l c2(ω) are the distances between the mirror image sound source and the second microphone at the first, second and third measurement points, respectively. Acoustic diagnostic equipment.

Images