Acoustic test device and acoustic test method

Abstract

To provide an acoustic test device and an acoustic test method capable of easily determining the existence / nonexistence of malfunctions of a product and an inspection device.SOLUTION: An acoustic test device 1 for testing a first microphone 102 and a second microphone 103, and an acoustic device 100 having a housing 101 with them provided on a sound collection surface includes: an anechoic box 10 having hollow inside; a first speaker 20 provided on the anechoic box 10a; an inspection part having a second speaker 38 and a third speaker 39; and an information processing part 50 including a signal output part 51a for outputting an electric signal to the speakers 20, 38, 39, a recording part 51b for acquiring recording signals of microphones 102, 103, and a determination part 51c for performing a determination on the basis of the recording signals.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an acoustic testing device and an acoustic testing method. [Background technology]

[0002] Patent document 1 describes a method for manufacturing a sensor (SEN) comprising the steps of: arranging a sensor element (SE) on a substrate (TR); arranging a cover (AF) on the sensor element (SE) so that the sensor element (SE) is sealed between the cover (AF) and the substrate (TR); adhering a carrier film (TF) onto the cover (AF); and forming an opening (SO) in the carrier film (TF) and the cover (AF), so that the openings (SO) in the carrier film (TF) and the cover (AF) at least partially overlap. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2015-513835 Summary of the Invention [Problem to be solved by the invention]

[0004] Furthermore, Patent Document 1 discloses a method for inspecting a manufactured sensor, in which the opening of the sensor to be tested and the acoustic outlet opening of the testing device are overlapped and sealed with a carrier film to form an acoustic coupling.

[0005] However, the carrier film described in Patent Document 1 is made of a soft material, and therefore wear and tear occurs due to friction. When the carrier film is worn and worn, acoustic coupling is not possible, and defects in the manufactured sensor (product) cannot be detected.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide an acoustic testing device and an acoustic testing method that can easily determine whether or not there is a defect in a product or an inspection device. [Means for solving the problem]

[0007] The acoustic testing device according to the present invention is an acoustic testing device for testing an acoustic device having a first microphone and a second microphone, and a housing in which the first microphone and the second microphone are provided on a sound collection surface, and includes an anechoic box with a hollow interior, a first speaker provided in the anechoic box so that an output unit is disposed inside the anechoic box, an inspection unit provided inside the anechoic box and to which the acoustic device is detachably provided, the inspection unit having a second speaker and a third speaker, and an electric signal output unit for outputting electric signals to the first speaker, the second speaker, and the third speaker. an information processing unit having a signal output unit that outputs a signal having a first microphone and a second microphone; an acquisition unit that acquires a first acquisition signal acquired by the first microphone and a second acquisition signal acquired by the second microphone; and a determination unit that makes a determination based on the first acquisition signal and the second acquisition signal, wherein the inspection unit has a main body that is provided with a recess that positions the acoustic device and a first hole and a second hole that open at one end to a bottom surface of the recess, and the second speaker and the third speaker have output units that are located inside the first hole and the second hole, respectively, and are configured to output sound toward the recess. a sound-insulating elastic member that is elastically deformable is provided on a bottom surface of the recess, the elastic member having a third hole and a fourth hole that are respectively provided at positions that overlap with the first hole and the second hole when viewed along the central axes of the first hole and the second hole, and the signal output unit is configured such that the first microphone covers the first hole and the third hole, the second microphone covers the second hole and the fourth hole, and the sound collecting surface abuts against the elastic member in an inspection state in which the acoustic device is provided in the recess. and outputs a second sound signal to the second speaker, and outputs the first sound signal to the first speaker while the second sound signal delayed by a first time is being input to the third speaker, and the determination unit converts the first recorded signal and the second recorded signal in the time domain into frequency spectra in the frequency domain, and determines whether or not there is a malfunction in at least one of the first microphone, the second microphone, and the inspection unit based on a frequency difference spectrum that is the difference between the frequency spectrum of the first recorded signal and the frequency spectrum of the second recorded signal.

[0008] The acoustic testing method according to the present invention includes an anechoic box having a hollow interior, a first speaker provided in the anechoic box so that an output unit is disposed inside the anechoic box, an inspection unit provided inside the anechoic box and having a first microphone and a second microphone, and an acoustic device having a housing with the first microphone and the second microphone provided on a sound collection surface, the inspection unit having a second speaker and a third speaker, a signal output unit that outputs electric signals to the first speaker, the second speaker, and the third speaker, and a signal output unit that outputs electric signals to the first microphone, the second speaker, and the third speaker. and an information processing unit having an acquisition unit that acquires a first acquired signal acquired by the first microphone and a second acquired signal acquired by the second microphone, and a determination unit that makes a determination based on the first acquired signal and the second acquired signal, wherein the inspection unit has a main body that is provided with a recess that positions the acoustic device and a first hole and a second hole that open at one end to a bottom surface of the recess, and the second speaker and the third speaker have output units that are located inside the first hole and the second hole, respectively, and are provided on the main body so as to output sound toward the recess, and the bottom surface of the recess is provided with a sound-insulating and an elastic member capable of elastic deformation is provided, the elastic member having a third hole and a fourth hole provided at a position overlapping the first hole and the second hole when viewed along the central axes of the first hole and the second hole, respectively, wherein the first microphone covers the first hole and the third hole, the second microphone covers the second hole and the fourth hole, and the acoustic device is provided in the recess so that the sound collecting surface abuts against the elastic member, and the signal output unit a step of outputting a second sound signal to the second speaker, and outputting a first sound signal to the first speaker while the second sound signal delayed by a first time is being input to the third speaker; a step of the acquisition unit acquiring the first acquired signal and the second acquired signal; a step of the determination unit converting the first acquired signal and the second acquired signal from the time domain into frequency spectra in the frequency domain; a step of the determination unit calculating a frequency difference spectrum which is a difference between the frequency spectrum of the first acquired signal and the frequency spectrum of the second acquired signal;and determining whether or not there is a defect in at least one of the first microphone, the second microphone, and the inspection unit based on the frequency difference spectrum.

[0009] According to the present invention, in an inspection state in which the first microphone covers the first and third holes, the second microphone covers the second and fourth holes, and the acoustic device is provided in the recess of the inspection unit so that its sound collection surface abuts the elastic member, a second sound signal is output to the second speaker, and the first sound signal is output to the first speaker while the second sound signal delayed by a first time is input to the third speaker, thereby obtaining a first recorded signal and a second recorded signal, converting the time-domain first recorded signal and the second recorded signal into frequency domain frequency spectra, and determining whether or not there is a malfunction in at least one of the first microphone, the second microphone, and the inspection unit based on the frequency difference spectrum, which is the difference between these signals. This makes it possible to easily determine whether or not there is a malfunction in the first microphone, the second microphone, or the inspection unit.

[0010] The information processing unit may have a storage unit that stores a reference frequency difference spectrum, and the determination unit may determine whether or not there is a malfunction based on a result of comparing the frequency difference spectrum with the reference frequency difference spectrum. This makes it possible to accurately determine whether or not there is a malfunction in the first microphone, the second microphone, or the inspection unit. It also makes it possible to easily determine whether there is a malfunction in the first microphone, the second microphone, or the inspection unit.

[0011] The first sound signal may be a 1 / f noise signal, and the second sound signal may be a signal that uniformly includes any frequency component, thereby making the difference in the low frequency range more pronounced in the amplitude difference spectrum and the phase difference spectrum.

[0012] The first sound signal may be a signal having only one or a plurality of discrete frequency components below 250 Hz, and the judgment unit may determine whether or not there is a malfunction in at least one of the first microphone and the second microphone based on the frequency difference spectrum.

[0013] In the inspection state, the second speaker and the third speaker may output sounds at an output level such that the values of the first and second collected signals are 75 dB, and in the inspection state and with the elastic member removed, the first speaker may output sounds at an output level such that the values of the first and second collected signals are 90 dB, thereby making it possible to determine whether or not there is a slight deformation (a minute gap) in the elastic member.

[0014] The distance between the diaphragm of the first speaker and the diaphragm of the first microphone and the distance between the diaphragm of the first speaker and the diaphragm of the second microphone may be approximately 100 mm or less, and the distance between the second diaphragm, which is the diaphragm of the second speaker, and the diaphragm of the first microphone, and the distance between the third diaphragm, which is the diaphragm of the third speaker, and the diaphragm of the second microphone may be approximately 17 mm or less. This makes it possible to determine whether or not there is an abnormality in the microphones. [Effects of the Invention]

[0015] According to the present invention, defects in products and inspection equipment can be detected. [Brief explanation of the drawings]

[0016] [Figure 1] 1A and 1B are diagrams showing an outline of an acoustic test device 1 according to an embodiment of the present invention, in which (A) is a perspective view of the exterior and (B) is a perspective view of the interior of the acoustic test device 1 exposed. [Figure 2] FIG. 2 is a perspective view showing an outline of the inspection unit 30. [Figure 3] FIG. 1 is a diagram showing an outline of an acoustic test device 1. [Figure 4] 1 is a diagram showing the positional relationship between microphones 102, 103, a main body 31, an elastic member 35, and speakers 38, 39. FIG. [Figure 5] 3 is a flowchart showing the flow of an inspection process in the acoustic test device 1. [Figure 6]10A and 10B show an example of a signal input to speakers 38 and 39, where (A) shows a signal input to speaker 38, (B) shows a signal input to speaker 39, and (C) and (D) are enlarged views of portions of (A) and (B) in the time axis direction, respectively. [Figure 7] 3 is a diagram showing an example of a signal input to a speaker 20. FIG. [Figure 8] FIG. 2 is a diagram showing an example of the waveform of a collected signal A. [Figure 9] 10 is a flowchart showing the process flow for determining the difference between collected signals A and B (step SP13). [Figure 10] (A) is an example of a reference amplitude difference spectrum, and (B) is an example of a reference phase difference spectrum. [Figure 11] 10 is a diagram showing a schematic diagram of a case where an inspection unit 30 has a problem. FIG. [Figure 12] 12A and 12B show examples of amplitude difference spectrum and phase difference spectrum when the defect shown in FIG. 11 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. [Figure 13] 10 is a diagram showing a schematic diagram of a case where an inspection unit 30 has a problem. FIG. [Figure 14] 14 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 13 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. [Figure 15] FIG. 10 is a diagram schematically illustrating a case where a microphone 102 has a malfunction. [Figure 16] 16 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 15 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. [Figure 17] FIG. 10 is a diagram schematically illustrating a case where a microphone 103 has a problem. [Figure 18] 18 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 17 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. [Figure 19]10A and 10B show examples of an amplitude difference spectrum and a phase difference spectrum when the sound insulation value L3' of the elastic member 35 near the microphone 102 is 20 dB, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. [Figure 20] 10A and 10B show examples of an amplitude difference spectrum and a phase difference spectrum when the sound insulation value L3' of the elastic member 35 near the microphone 103 is 20 dB, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. [Figure 21] FIG. 10 is a diagram showing an outline of a main body 31A according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of an acoustic testing device according to the present invention will be described with reference to the drawings.

[0018] First Embodiment 1A and 1B are diagrams showing an outline of an acoustic testing device 1 according to an embodiment of the present invention, with (A) being a perspective view of the exterior and (B) being a perspective view exposing the interior of the acoustic testing device 1. The acoustic testing device 1 is a device for inspecting an acoustic device 100 (not shown in FIG. 1, see FIG. 3), that is, microphones 102 and 103 (not shown in FIG. 1) that the acoustic device 100 has.

[0019] The acoustic testing device 1 mainly includes an anechoic box 10, a speaker 20 (corresponding to the first speaker of the present invention), and an inspection unit 30.

[0020] The anechoic box 10 is a hollow container that has sound insulation and sound absorption properties, and mainly comprises a lid 11 and a main body 12. A sound absorbing layer 13 is provided on substantially the entire inside of the lid 11 and the main body 12. However, the configuration of the anechoic box 10 is not limited to this. For example, a sound insulating layer may be provided on the outside of the sound absorbing layer 13.

[0021] A cavity 11a is formed inside the sound absorbing layer 13 of the lid 11. The speaker 20 is provided in the lid 11, and a diaphragm 21 (corresponding to the output section of the speaker 20 of the present invention) is disposed in the cavity 11a (inside the anechoic box 10).

[0022] A cavity 12a is formed inside the sound absorbing layer 13 of the main body 12. A sound absorbing material 14 is provided in the cavity 12a, and an inspection unit 30 is provided on the sound absorbing material 14. In other words, the inspection unit 30 is provided inside the anechoic box 10.

[0023] 2 is a perspective view showing an outline of the inspection unit 30. The acoustic device 100 is detachably provided to the inspection unit 30. The inspection unit 30 mainly has a main body 31, a plate-like portion 32, a pillar 33, a drive unit 34, an elastic member 35, and a base 36.

[0024] The main body 31 is plate-shaped or block-shaped, and is supported by a base 36. The main body 31 is provided with a recess 31c for positioning the acoustic device 100. The recess 31c is provided on an upper surface 31e of the main body 31.

[0025] Holes 31a and 31b (corresponding to the first and second holes of the present invention, respectively) are provided in main body 31. Holes 31a and 31b are holes that penetrate main body 31, and one end opens to bottom surface 31d of recess 31c. Speakers 38 and 39 (corresponding to the second and third speakers of the present invention, respectively; not shown in FIG. 2, but described in detail later) are provided near holes 31a and 31b of main body 31.

[0026] An elastic member 35 is provided on the bottom surface 31d. The elastic member 35 has sound insulation properties and is elastically deformable. For example, soft urethane foam, urethane foam, etc. can be used as the elastic member 35, but is not limited to these. The elastic member 35 has holes 35a and 35b (corresponding to the third and fourth holes of the present invention, respectively) that are provided at positions that overlap with the holes 31a and 31b when viewed along the central axes of the holes 31a and 31b. This allows the holes 31a and 31b to communicate with the recess 31c.

[0027] The plate-shaped portion 32 is provided above the main body portion 31 and is movable along the pillars 33. The drive unit 34 is a member that moves the plate-shaped portion 32 up and down. In FIG. 2, the plate-shaped portion 32 is disposed at the uppermost position (the position farthest from the main body portion 31). During inspection, the acoustic device 100 is inserted into the recess 31c, and the drive unit 34 moves the plate-shaped portion 32 downward so that the abutment portion 32a abuts against the acoustic device 100. The plate-shaped portion 32 is then further pressed downward to install the acoustic device 100 in the inspection unit 30. At this time, the plate-shaped portion 32 presses the acoustic device 100 toward the bottom surface 31d, so that the acoustic device 100 elastically causes the elastic member 35 to elastically contact the elastic member 35.

[0028] Fig. 3 is a diagram showing an outline of the acoustic testing device 1. Fig. 3 shows a state in which the acoustic device 100 is provided in the inspection section 30 (recess 31c).

[0029] The acoustic device 100 is an in-vehicle device that performs so-called hands-free calls such as emergency calls, inputs to a car navigation device installed in a car, and outputs audio from the car navigation device, and mainly comprises a housing 101, microphones 102 and 103 (corresponding to the first and second microphones of the present invention, respectively), and a speaker (not shown). The housing 101 is a hollow box-shaped member in which the microphones 102 and 103 are provided. The microphones 102 and 103 are provided on a surface 101a of the housing 101. The acoustic device 100 is inserted into the recess 31c.

[0030] Speakers 38, 39 are provided in a space 31f formed by base 36 below main body 31. Holes 31a, 31b penetrate main body 31 in the thickness direction, with one end opening to bottom surface 31d of recess 31c and the other end opening to space 31f. Speakers 38, 39 are provided in main body 31 such that output portions 38a, 39a (here, sound holes) are located inside holes 31a, 31b, respectively, and output sound toward recess 31c.

[0031] When acoustic device 100 is installed in recess 31c, microphone 102 covers holes 31a and 35a, microphone 103 covers holes 31b and 35b, and surface 101a abuts against elastic member 35. As a result, microphone 102 faces output section 38a, and microphone 103 faces output section 39a.

[0032] FIG. 4 is a diagram showing the positional relationship between the microphones 102, 103, the main body 31, the elastic member 35, and the speakers 38, 39 when the acoustic device 100 is installed in the recess 31c.

[0033] Microphones 102 and 103 are provided on a printed circuit board 101c provided on surface 101a. Surface 101a and printed circuit board 101c correspond to the sound collection surface of the present invention. Because elastic member 35 is elastically deformable, providing acoustic device 100 in recess 31c causes elastic member 35 to deform, bringing surface 101a (sound collection surface) and elastic member 35 into close contact.

[0034] The microphones 102 and 103 each include a MEMS chip 102a, a metal cap 102b, and a sound hole 102c. The sound hole 102c is formed on the surface 101a and the printed circuit board 101c (sound collection surface), respectively. The sound hole 102c exposes the MEMS chip 102a. The sound hole 103c exposes the MEMS chip 103a.

[0035] The speakers 38 and 39 have diaphragms 38b and 39b, respectively. Sound generated by the vibration of the diaphragms 38b and 39b is output from the output portions 38a and 39a.

[0036] The MEMS chip 102a and the output section 38a face a completely closed narrow space (small air chamber C1) formed by the sound hole 102c and the holes 31a and 35a, and the MEMS chip 103a and the output section 39a face a completely closed narrow space (small air chamber C2) formed by the sound hole 103c and the holes 31b and 35b. The sound hole 102c of the microphone 102 faces the output section 38a of the speaker 38, and the sound hole 103c of the microphone 103 faces the output section 39a of the speaker 39.

[0037] Because the elastic member 35 has sound-insulating properties, it is less susceptible to external disturbances, and under normal conditions, the sound output from the speaker 38 (output section 38a) is input only to the microphone 102 (MEMS chip 102a), and the sound output from the speaker 39 (output section 39a) is input only to the microphone 103 (MEMS chip 103a).

[0038] Returning to the explanation of Fig. 3, the acoustic test device 1 has an information processing unit 50. The information processing unit 50 is realized by a computer system mainly including a control unit 51, a storage unit 52, and an audio interface (I / F) 53.

[0039] The control unit 51 is a program-controlled device such as a CPU, and operates according to a program stored in the storage unit 52. The control unit 51 will be described in detail later.

[0040] The storage unit 52 is a memory device, a disk device, or the like, and holds a program executed by the control unit 51. The program may be provided by being stored in a computer-readable, non-transitory recording medium and copied to the storage unit 52. The storage unit 52 also operates as a work memory for the control unit 51. Furthermore, the storage unit 52 stores various setting information used in the processing of the control unit 51.

[0041] The audio I / F 53 converts digital signals into analog audio signals and outputs them to speakers 38 and 39, and converts analog signals collected by microphones 102 and 103 into digital signals.

[0042] The configuration of the information processing unit 50 shown in FIG. 1 is a main configuration for explaining the features of this embodiment, and does not exclude the configuration of a general information processing device, for example.

[0043] 3 includes a functional block diagram of the information processing unit 50. Functionally, the control unit 51 includes a signal output unit 51a, an acquisition unit 51b, and a determination unit 51c. Note that the functional components of the acoustic test device 1 may be further divided into more components depending on the processing content, or one component may execute the processing of multiple components.

[0044] The signal output unit 51a is a functional unit that outputs electrical signals to the speakers 20, 38, and 39. When the electrical signals output from the signal output unit 51a are input to the speakers 20, 38, and 39 via the audio I / F 53, the speakers 20, 38, and 39 vibrate their diaphragms, converting the electrical signals into air vibrations, i.e., sound. The electrical signals output by the signal output unit 51a to the speakers 20, 38, and 39 will be described in detail later.

[0045] Acquisition unit 51b is a functional unit that acquires the collected signals of microphones 102 and 103. Hereinafter, the collected signal of microphone 102 will be referred to as collected signal A (corresponding to the first collected signal of the present invention), and the collected signal of microphone 103 will be referred to as collected signal B (corresponding to the second collected signal of the present invention).

[0046] The determination unit 51c is a functional unit that makes a determination based on the collected signals A and B. For example, the determination unit 51c determines whether the microphones 102 and 103 are normal or not based on the collected signals A and B. Also, for example, the determination unit 51c determines whether a malfunction has occurred in the inspection unit 30 based on the collected signals A and B.

[0047] The determination unit 51c converts the collected signals A and B, which are time-series data (time-domain signals), into frequency spectra in the frequency domain. A frequency spectrum is an intensity distribution for each frequency component, broken down into frequency on the horizontal axis and signal intensity (magnitude) on the vertical axis. The frequency spectrum can be, for example, an amplitude spectrum, a power spectrum, or a phase spectrum, but in this embodiment, amplitude spectra and phase spectra are used. An amplitude spectrum is a function of frequency and amplitude, and a phase spectrum is a function of frequency and phase.

[0048] Furthermore, the determination unit 51c makes a determination based on a frequency difference spectrum, which is the difference between the frequency spectrum of collected signal A and the frequency spectrum of collected signal B. In this embodiment, the frequency difference spectrum is an amplitude difference spectrum, which is the difference between the amplitude spectrum A2 of collected signal A and the amplitude spectrum B2 of collected signal B, and a phase difference spectrum, which is the difference between the phase spectrum A3 of collected signal A and the phase spectrum B3 of collected signal B. The processing performed by the determination unit 51c will be described in detail later.

[0049] Fig. 5 is a flowchart showing the flow of the inspection process in the acoustic testing device 1. The process in Fig. 5 is performed by the information processing unit 50 in an inspection state in which the microphone 102 covers the holes 31a and 35a, the microphone 103 covers the holes 31b and 35b, and the acoustic device 100 is provided in the recess 31c so that the sound collection surface of the acoustic device 100 abuts against the elastic member 35. First, the signal output unit 51a outputs a signal (corresponding to the second sound signal of the present invention) to the speakers 38 and 39, respectively (step S10).

[0050] 6 shows an example of signals input to speakers 38 and 39, where (A) shows the signal input to speaker 38, (B) shows the signal input to speaker 39, and (C) and (D) are enlarged time-axis views of portions of (A) and (B) (encircled by dotted lines). The horizontal axis of FIG. 6 represents time (t), and the vertical axis represents amplitude.

[0051] In this embodiment, the signals input to speakers 38 and 39 are white noise signals. White noise is noise that contains all frequency components equally, and has a power spectral density that is essentially independent of frequency. The signal input to speaker 39 is a signal obtained by delaying the white noise input to speaker 38 by Δt (corresponding to the first time in the present invention). As a result, white noise is output from speakers 38 and 39, respectively. The white noise output from speaker 39 is delayed by Δt relative to the white noise output from speaker 38.

[0052] Returning to the description of Fig. 5, the signal output unit 51a outputs a signal (corresponding to the first sound signal of the present invention) different from the signal input to the speakers 38 and 39 to the speaker 20 while outputting a white noise signal to the speakers 38 and 39 (step S11).

[0053] FIG. 7 is a diagram showing an example of a signal input to the speaker 20. The horizontal axis of FIG. 7 represents time (t), and the vertical axis represents amplitude. In this embodiment, the signal input to the speaker 20 is a swept-sine (TSP) signal. A TSP signal is a type of swept sine wave, and is a sine wave whose frequency changes from 0 Hz to an upper limit frequency within the time length of one Fast Fourier Transform (FFT) calculation. Here, the TSP signal is a signal whose frequency monotonically increases along the time axis.

[0054] Returning to the explanation of Fig. 5, the recording unit 51b acquires the recorded signals A and B recorded by the microphones 102 and 103, respectively (step SP12). Since sound is being output from the speakers 38 and 39 (step SP10) while sound is being output from the speaker 20 (step S11), the recorded signals A and B are the sounds output from the speakers 38 and 39 superimposed on the sounds output from the speaker 20.

[0055] Figure 8 shows an example of the waveform of collected signal A. Collected signal A has a swept sine signal (enclosed by a dotted line) superimposed on white noise. Like collected signal A, collected signal B also has a swept sine signal superimposed on white noise (however, delayed by Δt with respect to the white noise of collected signal A). In this way, collected signals A and B are time-series data (time-domain signals) arranged in chronological order.

[0056] Returning to the explanation of Fig. 5, the decision unit 51c determines the difference between the collected signals A and B acquired in step SP12 (step SP13). Fig. 9 is a flowchart showing the process flow for determining the difference between the collected signals A and B (step SP13).

[0057] First, the determination unit 51c extracts the portion where the swept sine signal is superimposed from the collected signals A and B (step SP21). For example, if sound is output from the speaker 20 from time T1 to time T2, any section including the section from time T1 to time T2 is extracted from the collected signals A and B. The extracted collected signals A and B are designated as collected signals A-1 and B-1, respectively.

[0058] Next, the determination unit 51c performs a fast Fourier transform on the collected signals A-1 and B-1 to convert the time domain functions into frequency domain functions (step SP22). In this embodiment, the determination unit 51c converts the collected signals A-1 and B-1 into amplitude spectra A2 and B2 and phase spectra A3 and B3. Note that the conversion of the time domain functions into frequency domain functions is not limited to the fast Fourier transform, and for example, a discrete Fourier transform (DFT) may also be used.

[0059] Next, the judgment unit 51c calculates the difference between the amplitude spectrum A2 and the amplitude spectrum B2 (hereinafter referred to as the amplitude difference spectrum) using equation (1), and calculates the difference between the phase spectrum A3 and the phase spectrum B3 (hereinafter referred to as the phase difference spectrum) using equation (2) (step SP23). Amplitude difference spectrum = Amplitude spectrum A2 - Amplitude spectrum B2 (1) Phase difference spectrum = Phase spectrum A3 - Phase spectrum B3 (2) In this way, the difference between the collected signals A and B is determined by the determining section 51c.

[0060] Returning to the description of Fig. 5, the determination unit 51c determines whether or not there is a problem with at least one of the microphones 102, 103 and the inspection unit 30, based on the amplitude difference spectrum and the phase difference spectrum obtained in step SP13 (step SP14). In this embodiment, the determination unit 51c makes the determination based on the result of comparing the reference frequency difference spectrum stored in the storage unit 52 with the amplitude difference spectrum and the phase difference spectrum.

[0061] 10A and 10B are diagrams showing examples of a reference amplitude difference spectrum and a reference phase difference spectrum, which are reference frequency difference spectra. Fig. 10A is an example of a reference amplitude difference spectrum, and Fig. 10B is an example of a reference phase difference spectrum. The reference amplitude difference spectrum and the reference phase difference spectrum are amplitude difference spectrum and phase difference spectrum obtained by performing the processes of steps SP10 to SP14 using microphones 102, 103 and inspection unit 30 that are known to be normal (not defective) before the inspection process is performed, and are stored in advance in storage unit 52.

[0062] The determination unit 51c determines where the defect exists based on how the amplitude difference spectrum and phase difference spectrum calculated in step SP13 differ from the reference amplitude difference spectrum and reference phase difference spectrum. For example, the determination unit 51c can use a known technique such as pattern recognition to determine the difference between the amplitude difference spectrum and phase difference spectrum calculated in step SP13 and the reference amplitude difference spectrum and reference phase difference spectrum.

[0063] If the amplitude difference spectrum and phase difference spectrum obtained in step SP13 have the same shapes as the reference amplitude difference spectrum and reference phase difference spectrum, the determining unit 51c determines that the microphones 102, 103 and the inspection unit 30 are all normal.

[0064] Next, a case where there is a problem with either the microphones 102, 103 or the inspection unit 30 will be described.

[0065] <When there is a problem with the inspection unit 30 1> FIG. 11 is a diagram schematically illustrating a case where there is a defect in the inspection unit 30. FIG. 11 illustrates a state in which the thickness of a portion of the elastic member 35 is reduced, forming a gap G1 near the microphone 102. In this case, the space (sound hole 102c and holes 31a, 35a) where the MEMS chip 102a and the output unit 38a face each other does not form a small air chamber. Therefore, the sound (especially low-pitched sounds) output from the speaker 20 is transmitted through the gap G1, and the MEMS chip 102a collects the sound (especially low-pitched sounds) output from the speaker 38 and the sound (especially low-pitched sounds) output from the speaker 20.

[0066] FIG. 12 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 11 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. For illustrative purposes, the two-dot chain line in FIG. 12(A) indicates the reference amplitude difference spectrum, and the two-dot chain line in FIG. 12(B) indicates the reference phase difference spectrum. Because the low-frequency sound leaking through the gap G1 is collected only by the MEMS chip 102a, the low-frequency portion X1 below 6000 Hz in the amplitude difference spectrum is larger than the reference amplitude difference spectrum. In particular, the difference between the low-frequency portion X2 from 3000 Hz to 6000 Hz and the reference amplitude difference spectrum is large. Furthermore, the low-frequency portion Y1 from 3000 Hz to 6000 Hz in the phase difference spectrum is curved so as to be convex upward. Furthermore, the mid-frequency portion Y2 from 5000 Hz to 8000 Hz in the phase difference spectrum is smaller than the reference amplitude difference spectrum. In this way, the determining unit 51c determines that there is a gap G1 near the microphone 102 when the amplitude difference spectrum and the phase difference spectrum have the characteristics of the low-pitched sounds X1, X2, Y1, and Y2.

[0067] <When there is a problem with the inspection unit 30 2> FIG. 13 is a diagram schematically illustrating a case where there is a defect in the inspection unit 30. FIG. 13 illustrates a state in which the thickness of a portion of the elastic member 35 is reduced, forming a gap G2 near the microphone 103. In this case, the space (sound hole 103c and holes 31b, 35b) where the MEMS chip 103a and the output unit 39a face each other does not form a small air chamber. Therefore, the sound (especially low-pitched sounds) output from the speaker 20 is transmitted through the gap G2, and the sound (especially low-pitched sounds) output from the speaker 39 and the sound (especially low-pitched sounds) output from the speaker 20 are collected by the MEMS chip 103a.

[0068] FIG. 14 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 13 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. For illustrative purposes, the two-dot chain line in FIG. 14(A) indicates the reference amplitude difference spectrum, and the two-dot chain line in FIG. 14(B) indicates the reference phase difference spectrum. Because the low-frequency sound leaking through the gap G2 is collected only by the MEMS chip 103a, the low-frequency portion X3 below 6000 Hz in the amplitude difference spectrum is smaller than the reference amplitude difference spectrum. Furthermore, the value in the mid-frequency portion Y2 between 5000 Hz and 5500 Hz in the phase difference spectrum rises sharply, and accordingly, the values in the mid- to high-frequency ranges also increase generally. In this way, when the amplitude difference spectrum and the phase difference spectrum have characteristics of the low-frequency portions X3 and Y3, the determination unit 51c determines that a defect exists in which the gap G2 exists near the microphone 103.

[0069] <If there is a problem with microphone 102> 15 is a diagram showing a schematic diagram of a case where there is a malfunction in microphone 102. A hole H1 is opened in metal cap 102b of microphone 102, and sound (especially low tones) output from speaker 20 enters through hole H1, and MEMS chip 102a collects sound output from speaker 38 and sound (especially low tones) output from speaker 20.

[0070] FIG. 16 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 15 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. For illustrative purposes, the two-dot chain line in FIG. 16(A) indicates the reference amplitude difference spectrum, and the two-dot chain line in FIG. 16(B) indicates the reference phase difference spectrum. Because low-pitched sounds are collected on the MEMS chip 102a through the hole H1, the value of the lowest note X4 near 0 Hz in the amplitude difference spectrum is significantly larger than the value of the reference amplitude difference spectrum. Furthermore, the value decreases rapidly from the lowest note X4, and is smaller than the value of the reference amplitude difference spectrum in the low-pitched note X5 between 100 Hz and 1200 Hz. Furthermore, the value of the lowest note Y4 near 0 Hz in the phase difference spectrum is significantly larger than the value of the reference phase difference spectrum. Furthermore, the value decreases rapidly from the lowest note Y4. In this way, if the amplitude difference spectrum and the phase difference spectrum have the characteristics of the low-pitched notes X4, X5, and Y4, the determination unit 51c determines that the microphone 102 has a defect.

[0071] <If there is a problem with microphone 103> 17 is a diagram showing a schematic diagram of a case where there is a malfunction in microphone 103. A hole H2 is opened in metal cap 103b of microphone 103, and sound (especially low tones) output from speaker 20 enters through hole H2, and MEMS chip 103a collects the sound output from speaker 39 and the sound (especially low tones) output from speaker 20.

[0072] FIG. 18 shows an example of an amplitude difference spectrum and a phase difference spectrum when the defect shown in FIG. 17 exists, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. For illustrative purposes, the two-dot chain line in FIG. 18(A) indicates the reference amplitude difference spectrum, and the two-dot chain line in FIG. 18(B) indicates the reference phase difference spectrum. Because low-pitched sounds are collected in the MEMS chip 103a through the hole H2, the value of the low-pitched part X6 from 0 Hz to 1200 Hz in the amplitude difference spectrum is large. Furthermore, the value of the lowest-pitched part Y5 near 0 Hz in the phase difference spectrum is small. In this way, when the amplitude difference spectrum and the phase difference spectrum have characteristics of the low-pitched parts X6 and Y5, the determination unit 51c determines that there is a defect in the microphone 103.

[0073] According to this embodiment, it is possible to easily determine whether or not there is a defect in the product (microphones 102, 103) and the inspection unit 30 based on the amplitude difference spectrum and the phase difference spectrum.

[0074] Furthermore, according to this embodiment, by comparing the amplitude difference spectrum and the phase difference spectrum with the reference amplitude difference spectrum and the reference phase difference spectrum, it is possible to easily determine the location of the defect (whether the defect is in microphone 102 or microphone 103, or in the inspection unit).

[0075] In the present embodiment, the signal output unit 51a outputs a white noise signal (second sound signal) to the speakers 38 and 39, and outputs a TSP signal (first sound signal) to the speaker 20, but the signal output by the signal output unit 51a is not limited to this. The signal output from the signal output unit 51a can be arbitrarily selected from, for example, a white noise signal, a pink noise signal, an M-sequence signal, a TSP signal, a pink TSP signal (Log-Swept Sine), a signal having only one frequency component (hereinafter referred to as a single tone), and a signal having only a plurality of discrete frequency components (hereinafter referred to as a multi-tone).

[0076] Pink noise is white noise passed through a low-pass filter, and when graphed with frequency on the horizontal axis and energy on the vertical axis, the graph slopes downward toward the higher frequency bands. M-sequence signals are pseudorandom noise that take on values of 1 and -1. Pink TSP signals are swept sine waves whose logarithmic frequency increases in proportion to time, and are characterized by the high energy of their low-frequency components. Multi-tone signals have only frequency components of, for example, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, and 4 kHz (the frequency components are discrete).

[0077] Although all of the above types of signals can be used as the signal (corresponding to the second sound signal) that the signal output unit 51a outputs to the speakers 38, 39, it is desirable to use a signal (for example, a white noise signal, an M-sequence signal, or a TSP signal) that uniformly includes components within the band (0≦fs / 2, where fs is the sampling frequency) of the microphones 102, 103. For example, if the sampling frequency fs of the microphones 102, 103 is 24 kHz, it is desirable for the signal output unit 51a to use, as the signal to be output to the speakers 38, 39, a white noise signal, an M-sequence signal, or a TSP signal that uniformly includes components up to 12 kHz.

[0078] Although all of the above types of signals can be used as the signal (corresponding to the first sound signal) output from the signal output unit 51a to the speaker 20, it is preferable to use a 1 / f noise signal that has a large amount of energy in the low frequency range. Examples of the 1 / f noise signal include a pink noise signal and a pink TSP signal. This makes it possible to highlight differences in the low frequency range in the amplitude difference spectrum and the phase difference spectrum.

[0079] Furthermore, in this embodiment, the judgment unit 51c judges whether or not there is a malfunction in any of the microphones 102, 103, and the inspection unit 30, but the judgment unit 51c may only judge whether or not there is a malfunction in any of the microphones 102, 103, or the judgment unit 51c may only judge whether or not there is a malfunction in the inspection unit 30.

[0080] For example, when the determination unit 51c determines whether or not there is a problem with either of the microphones 102 and 103 (it does not determine whether or not there is a problem with the inspection unit 30), the determination can be made based on the characteristics of the lowest frequency parts Y4 and Y5 near 0 Hz in the phase difference spectrum. Therefore, a single tone or multiple tones of frequencies included in the lowest frequency part can be used as the signal (corresponding to the first sound signal) that the signal output unit 51a outputs to the speaker 20. For example, the first sound signal may be a single tone of 125 Hz or multiple tones of 125 Hz, 250 Hz, and 500 Hz. However, it is desirable that the first sound signal be a signal that has only one or multiple discrete frequency components below 250 Hz.

[0081] Furthermore, for example, when the judgment unit 51c uses a single tone or multi-tone of a frequency included in the lowest part as the first sound signal to determine whether there is a problem with either of the microphones 102 and 103, it may be possible to determine whether there is a problem with either of the microphones 102 and 103 using only the phase difference spectrum without using the amplitude difference spectrum.

[0082] In the present embodiment, the determination unit 51c determines whether or not there is a malfunction in the microphones 102, 103 or the inspection unit 30 by determining, by pattern recognition or the like, how the amplitude difference spectrum and phase difference spectrum calculated in step SP13 differ from the reference amplitude difference spectrum and reference phase difference spectrum. However, the method by which the determination unit 51c determines whether or not there is a malfunction is not limited to this. For example, the determination unit 51c may determine whether or not there is a malfunction by comparing the values of the amplitude difference spectrum and phase difference spectrum calculated in step SP13 with a threshold value, rather than comparing them with the reference amplitude difference spectrum and reference phase difference spectrum. The determination unit 51c may also determine whether or not there is a malfunction by performing an abnormality determination (such as outlier detection) on the amplitude difference spectrum and phase difference spectrum using machine learning. However, by comparing the amplitude difference spectrum and phase difference spectrum calculated in step SP13 with the reference amplitude difference spectrum and reference phase difference spectrum, the presence or absence of a malfunction can be accurately determined.

[0083] Furthermore, in this embodiment, there are no particular limitations on the volume (output level) of the sound output from speakers 20, 38, and 39, but by adjusting the output level, it is possible to more accurately detect a malfunction in any of microphone 102, microphone 103, and inspection unit 30. The output level for making a highly accurate determination will be described below.

[0084] The output levels of speakers 38 and 39 are adjusted so that, with elastic member 35 in place, signal output unit 51a inputs a signal to speakers 38 and 39 to play sound (e.g., white noise) from speakers 38 and 39, and the measured values of microphones 102 and 103, i.e., collected signals A and B, are 75 dB (decibels). Furthermore, the output level of speaker 20 is adjusted so that, with elastic member 35 removed, signal output unit 51a inputs a signal to speaker 20 to play sound (e.g., Pink-TSP) from speaker 20, and the value of collected signals A and B from 75 dB is 90 dB (decibels). This allows slight deterioration of elastic member 35 to be detected while minimizing the effect of the playback volume of speaker 20 on the playback sound of speakers 38 and 39.

[0085] The reason for this will be explained below. If the playback volume of speakers 38 and 39 is L1 (dB), the playback volume of speaker 20 is L2 (dB), and the sound insulation value of elastic member 35 is L3 (dB), the audio level L4 (dB) obtained by combining playback volume L1 and playback volume L2 is expressed by equation (3).

number

[0086] If L1 is 75 dB, L2 is 90 dB, and L3 is 30 dB (normal value), L4 is calculated as 90.000137 dB using formula (3), and the contamination level D1 of the volume of speakers 38 and 39 relative to the volume of speaker 20 is calculated as 0.000137 dB using formula (4). D1=L4-L2=90.000137dB-90dB=0.000137dB...(4) Therefore, the influence of the volume of the speakers 38 and 39 on the volume of the speaker 20 is very small and can be ignored.

[0087] Furthermore, the audio level L5 (dB) obtained by combining the playback volume L1 and the playback volume L2 is expressed by equation (5).

number

[0088] If L1 is 75 dB, L2 is 90 dB, and L3 is 30 dB, L5 is calculated as 75.135209 dB from equation (4), and the contamination level D2 of the volume of speaker 20 relative to the volumes of speakers 38 and 39 is calculated as 0.135209 dB from equation (6). D2=L5-L1=75.135209dB-75dB=0.135209dB...(6) Therefore, the influence of the volume of the speaker 20 on the volume of the speakers 38 and 39 is very small and can be ignored.

[0089] Next, we will explain a case where the sound insulation value of elastic member 35 has changed from the normal value of L3=30 dB to L3'=20 dB due to deterioration of elastic member 35. In this case, the sound level L5 (dB) is calculated as 76.19331 dB by substituting L3' for L3 in equation (5), and the mixing level D2 of the volume of speaker 20 relative to the volume of speakers 38 and 39 is calculated as 1.19331 dB from equation (6). In this way, the influence of the volume of speaker 20 on the volume of speakers 38 and 39 becomes greater than a negligible level.

[0090] The amplitude difference spectrum and phase difference spectrum when the sound insulation value L3' of the elastic member 35 is 20 dB will be described. Fig. 19 shows an example of the amplitude difference spectrum and phase difference spectrum when the sound insulation value L3' of the elastic member 35 is 20 dB near the microphone 102, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. Fig. 20 shows an example of the amplitude difference spectrum and phase difference spectrum when the sound insulation value L3' of the elastic member 35 is 20 dB near the microphone 103, where (A) is the amplitude difference spectrum and (B) is the phase difference spectrum. The two-dot chain lines in Figs. 19 and 20(A) indicate the reference amplitude difference spectrum, and the two-dot chain lines in Figs. 19 and 20(B) indicate the reference phase difference spectrum. 19 and 20 are graphs different from the reference amplitude difference spectrum and reference phase difference spectrum, and are similar to the amplitude difference spectrum and phase difference spectrum (FIGS. 12 and 14) when there is a defect in the inspection unit 30, but have some different characteristics. Therefore, by setting the playback volume of speakers 38 and 39 to 75 (dB) and the playback volume of speaker 20 to 90 (dB), it is possible to detect a defect in elastic member 35 based on the amplitude difference spectrum and phase difference spectrum.

[0091] Furthermore, in this embodiment, the distance between speaker 20 and MEMS chips 102a, 103a, and the distance between speakers 38, 39 and MEMS chips 102a, 103a are not particularly limited, but by adjusting these distances (positional relationships of the components), it is possible to detect with higher accuracy any malfunction of microphone 102, microphone 103, or inspection unit 30. The positional relationships of the components required for highly accurate determination will be described below.

[0092] In order to detect sealing abnormalities (such as the presence or absence of holes H1, H2) in the metal caps 102b, 103b of the microphones 102, 103, it is desirable that the distance S between the diaphragm of the microphones 102, 103 (MEMS chips 102a, 103a) (in reality, the diaphragm is provided inside the MEMS chips 102a, 103a, but since the MEMS chips 102a, 103a are tiny, the diaphragm inside the MEMS chips 102a, 103a can be considered to be the same as the MEMS chips 102a, 103a) and the diaphragm of the speaker 20 is shorter than the wavelength of the sound to be measured.

[0093] If the speed of sound is v [m / s] and the wavelength is λ [m], the frequency f can be expressed by the following formula (5). Note that the speed of sound is 340 [m / s] (the speed of sound when the temperature is 15 [℃]). f=v÷λ[Hz]=340÷λ[Hz]...(5)

[0094] The range of measurable frequencies f can be expressed by the following equation (6). 0≦f<(340 / S) (Hz) (6) If the distance S is set to 100 mm or less, abnormalities in the sealing of the metal caps 102b, 103b can be detected in the frequency band of 3400 Hz or less using equation (6). As shown in Figures 16 and 18, abnormalities in the sealing of the metal caps 102b, 103b (such as the presence or absence of holes H1, H2) are significantly affected in the low frequency range, particularly at frequencies of 2000 Hz or less, in the amplitude difference spectrum and phase difference spectrum. Therefore, by setting the distance S to 100 mm or less, abnormalities in the sealing of the metal caps 102b, 103b can be detected using the acoustic testing device 1.

[0095] In order to detect an abnormality (gaps G1, G2) in the elastic member 35, the small air chambers C1, C2 must be considered to be a free sound field (a range in which a point sound source exists without being affected by reflections). To achieve this, the distance s between the diaphragms (MEMS chips 102a, 103a) of the microphones 102, 103 and the diaphragms 38b, 39b of the speakers 38, 39 must be shorter than the wavelength of the sound to be measured.

[0096] When the distance s is approximately 17 mm or less, the range of frequency f that can be measured without being affected by reflection is 20,000 [Hz] or less (see formula (7)). When the distance s is approximately 10 mm or less, the range of frequency f that can be measured without being affected by reflection is 34,000 [Hz] or less (see formula (8)). Similarly, when the distance s is approximately 6 mm or less, the range of frequency f that can be measured without being affected by reflection is 56,666 [Hz] or less (see formula (9)). 0≦f<(340÷0.017)=0≦f<20,000[Hz]...(7) 0≦f<(340÷0.01)=0≦f<34,000[Hz]···(8) 0≦f<(340÷0.006)=0≦f<56,666[Hz]...(9)

[0097] The frequencies that humans can hear (audible range) are 20 Hz to 20,000 Hz, so by setting the distance s to approximately 17 mm or less, it is possible to measure frequencies in the audible range using the acoustic test device 1. Furthermore, by shortening the distance s to approximately 6 mm or less, it is possible to use the acoustic test device 1 to perform measurements in the range of 56,000 Hz or less, which is the frequency that can be output by a general sound source (reproduction frequency).

[0098] The diameter of the small air chambers C1 and C2 is approximately 6 mm. Due to the viscosity of air, a velocity gradient of the air occurs between the vicinity of the walls of the holes 31 a and 31 b and the center of the holes 31 a and 31 b. However, if the diameter of the holes 31 a and 31 b is small, the effect of viscosity cannot be ignored even at the center of the holes 31 a and 31 b. Therefore, in this embodiment, it is desirable to set the diameter of the holes 31 a and 31 b to approximately 6 mm, which is considered to be unaffected by viscosity.

[0099] Furthermore, in this embodiment, the acoustic testing device 1 is configured to be able to test two microphones 102 and 103, but the number of microphones that the acoustic testing device 1 can test is not limited to two. The acoustic testing device 1 can be configured to be able to test any number of microphones greater than or equal to two.

[0100] For example, by providing four holes 31a, 31b, 31g, and 31h in main body 31A as shown in Fig. 21, a total of four microphones can be tested in each of holes 31a, 31b, 31g, and 31h. Four speakers and test microphones a, b, g, and h are provided in holes 31a, 31b, 31g, and 31h, respectively, and the difference between the frequency spectrum of microphone a and the frequency spectrum of microphone b, the difference between the frequency spectrum of microphone a and the frequency spectrum of microphone c, and the difference between the frequency spectrum of microphone a and the frequency spectrum of microphone d are calculated. These are then compared with the reference frequency difference spectrum, thereby determining whether or not there are any defects in microphones a, b, g, and h and the elastic member (not shown in Fig. 21) provided in main body 31A.

[0101] The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present invention.

[0102] In the present invention, the term "approximately" is a concept that includes not only cases where something is strictly identical, but also errors or deformations that do not cause loss of identity. For example, an "approximately cubic shape" is not limited to a strict cubic shape. Furthermore, for example, when expressing something as simply vertical, coincident, etc., it includes not only cases where something is strictly vertical, coincident, etc., but also cases where something is approximately vertical, approximately coincident, etc. Furthermore, in the present invention, the term "nearby" is a concept that indicates, for example, when referring to the vicinity of A, that something is close to A and may or may not include A. [Explanation of symbols]

[0103] 1: Acoustic test equipment 10: Anechoic box 11: Lid part 12: Main body 11a, 12a: Cavity 13: Sound absorbing layer 14: Sound absorbing material 20: Speaker 21: Vibration plate 30: Inspection Department 31, 31A: Main body 31a, 31b: Hole 31c: recess 31d: Bottom 31e :face 31f: Space 31g, 31h: hole 32: Plate-shaped part 32a: Contact part 33: Pillar 34: Drive unit 35: Elastic member 35a, 35b: Hole 36: Foundation 38, 39: Speaker 38a, 39a: Output section 38b, 39b: Vibration plate 50: Information Processing Department 51: Control unit 51a: signal output section 51b: Acquisition section 51c: Judgment section 52: Storage section 53: Audio I / F 100: Sound equipment 101: Housing 101a :face 101c: Printed circuit board 102, 103: Microphone 102a, 103a: MEMS chip 102b, 103b: Metal cap 102c, 103c: Sound hole

Claims

1. An acoustic testing apparatus for testing an acoustic device having a first microphone and a second microphone, and a housing on which the first microphone and the second microphone are mounted on a sound-collecting surface, An anechoic chamber with a hollow interior, A first speaker is provided in the anechoic chamber such that the output section is located inside the anechoic chamber, An inspection unit provided inside the anechoic chamber, on which the acoustic device is detachably mounted, comprising an inspection unit having a second speaker and a third speaker, An information processing unit having: a signal output unit that outputs electrical signals to the first speaker, the second speaker, and the third speaker; an acquisition unit that acquires a first acquisition signal acquired by the first microphone and a second acquisition signal acquired by the second microphone; and a determination unit that performs a determination based on the first acquisition signal and the second acquisition signal. Equipped with, The inspection unit has a main body portion provided with a recess for positioning the sound device, and a first hole and a second hole, one end of which opens to the bottom surface of the recess. The second speaker and the third speaker are provided in the main body such that their output sections are located inside the first hole and the second hole, respectively, and they output sound toward the recess. An elastic member that has sound-insulating properties and is elastically deformable is provided on the bottom surface of the recess. The elastic member has a third hole and a fourth hole, respectively, which are provided at positions that overlap with the first hole and the second hole when viewed along the central axis of the first hole and the second hole. The signal output unit, in an inspection state in which the acoustic device is provided in the recess such that the first microphone covers the first and third holes, the second microphone covers the second and fourth holes, and the sound-collecting surface is in contact with the elastic member, outputs a second sound signal to the second speaker, and while the second sound signal, which has been delayed by a first time, is input to the third speaker, outputs a first sound signal to the first speaker. The determination unit converts the first and second acquired signals in the time domain into frequency spectra in the frequency domain, and determines whether there is a malfunction in at least one of the first microphone, the second microphone, and the inspection unit based on the frequency difference spectrum, which is the difference between the frequency spectrum of the first acquired signal and the frequency spectrum of the second acquired signal. An acoustic testing apparatus characterized by the following features.

2. The information processing unit has a storage unit in which the reference frequency difference spectrum is stored, The determination unit determines whether or not there is a defect based on the result of comparing the frequency difference spectrum with the reference frequency difference spectrum. The acoustic testing apparatus according to feature 1.

3. The first sound signal is a 1 / f noise signal, The aforementioned second sound signal is a signal that uniformly contains arbitrary frequency components. The acoustic testing apparatus according to claim 1 or 2, characterized by the features described above.

4. The first sound signal is a signal having only one or a plurality of discrete frequency components of 250 Hz or less. The determination unit determines, based on the frequency difference spectrum, whether or not there is a malfunction in at least one of the first microphone and the second microphone. The acoustic testing apparatus according to claim 1 or 2, characterized by the features described above.

5. In the aforementioned test state, the second speaker and the third speaker output sound at an output level such that the values ​​of the first and second acquisition signals are 75 dB. In the aforementioned inspection state and with the elastic member removed, the first speaker outputs sound at an output level such that the values ​​of the first and second acquired signals are 90 dB. The acoustic testing apparatus according to claim 1 or 2, characterized by the features described above.

6. The distance between the diaphragm of the first speaker and the diaphragm of the first microphone, and the distance between the diaphragm of the first speaker and the diaphragm of the second microphone are approximately 100 mm or less. The diaphragm of the second speaker, which is the diaphragm of the second speaker, and the diaphragm of the first microphone, and the diaphragm of the third speaker, which is the diaphragm of the third microphone, are approximately 17 mm or less in diameter. The acoustic testing apparatus according to claim 1 or 2, characterized by the features described above.

7. An anechoic chamber with a hollow interior, A first speaker is provided in the anechoic chamber such that the output section is located inside the anechoic chamber, An inspection unit is provided inside the anechoic chamber and is detachably equipped with an acoustic device having a first microphone and a second microphone, and a housing on which the first microphone and the second microphone are provided as sound-collecting surfaces, the inspection unit having a second speaker and a third speaker, An information processing unit having: a signal output unit that outputs electrical signals to the first speaker, the second speaker, and the third speaker; an acquisition unit that acquires a first acquisition signal acquired by the first microphone and a second acquisition signal acquired by the second microphone; and a determination unit that performs a determination based on the first acquisition signal and the second acquisition signal. Equipped with, The inspection unit has a main body portion provided with a recess for positioning the sound device, and a first hole and a second hole, one end of which opens to the bottom surface of the recess. The second speaker and the third speaker are provided in the main body such that their output sections are located inside the first hole and the second hole, respectively, and they output sound toward the recess. An elastic member that has sound-insulating properties and is elastically deformable is provided on the bottom surface of the recess. The acoustic testing method involves inspecting the acoustic device using an acoustic testing apparatus having a third hole and a fourth hole, respectively, which are provided at positions that overlap with the first hole and the second hole when viewed along the central axis of the first hole and the second hole, the elastic member being: In an inspection state in which the acoustic device is provided in the recess such that the first microphone covers the first hole and the third hole, the second microphone covers the second hole and the fourth hole, and the sound-collecting surface is in contact with the elastic member, the signal output unit outputs a second sound signal to the second speaker, and while the second sound signal, which has been delayed by a first time, is input to the third speaker, it outputs a first sound signal to the first speaker. The acquisition unit performs the steps of acquiring the first acquisition signal and the second acquisition signal, The determination unit performs the steps of converting the first acquired signal and the second acquired signal in the time domain into frequency spectra in the frequency domain, The determination unit performs the step of determining a frequency difference spectrum, which is the difference between the frequency spectrum of the first acquired signal and the frequency spectrum of the second acquired signal. The determination unit determines whether or not there is a malfunction in at least one of the first microphone, the second microphone, and the inspection unit based on the frequency difference spectrum. An acoustic testing method characterized by including [a specific component].

Images