JP7350456B2 - Acoustic test equipment and acoustic test method - Google Patents

Description

The present invention relates to an acoustic testing device and an acoustic testing method.

Patent Document 1 discloses that a flat baffle plate is sandwiched between a flat array housing surface and the baffle plate, and the array housing surface and the baffle plate are positioned parallel to each other. A plurality of acoustically transparent pillars are arranged on the surface of a baffle plate or array housing to form a space whose outer periphery is open around a central axis, and a circular center is aligned with the central axis to form a space. A microphone array adjustment device is described that includes a speaker that is directed toward the subject, and a plurality of microphones that are provided at predetermined intervals on a circumference centered on a central axis that is perpendicular to the surface of an array housing.

Japanese Patent Application Publication No. 2016-54455

Patent Document 1 describes that the outer diameter of the support is set to 1/4 or less of the upper limit frequency of the voice to make the support acoustically transparent so as not to affect the sensitivity characteristics and phase characteristics of the microphone acoustically. has been done. However, when measuring the performance of a microphone using the microphone array adjustment device described in Patent Document 1, it is difficult to measure the performance of a microphone when the volume is low or the distance between the sound source and the microphone is If the values are close to each other, there is a risk that the performance of the microphone cannot be measured accurately.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an acoustic testing device that can accurately measure the performance of a microphone even when the volume is low or when the distance between the sound source and the microphone is short. purpose.

An acoustic testing device according to the present invention is an acoustic testing device for measuring the characteristics of a microphone, and includes a holding member having a plate-shaped portion provided with a cylindrical hole penetrating in the thickness direction, and a holding member inserted into the cylindrical hole. a sound source that has a columnar section and emits sound from the distal end surface of the columnar section, the microphone is provided adjacent to the first surface of the plate section, and the holding member is located in the columnar hole. a positioning part for arranging the microphone so that the cylindrical hole and the microphone overlap when viewed along the axis of is about 6 mm to about 17 mm or less, and is inserted into the cylindrical hole so that the tip surface faces the microphone from the second surface side of the plate-shaped portion, which is the surface opposite to the first surface. It is characterized by

According to the present invention, the holding member has a plate-shaped portion provided with a cylindrical hole penetrating in the thickness direction, and the microphone is provided adjacent to the first surface of the plate-shaped portion. The sound source has a columnar part inserted into the cylindrical hole, and emits sound from the tip surface of the columnar part. The holding member has a positioning part for arranging the microphone so that the cylindrical hole and the microphone overlap when viewed along the axis of the cylindrical hole. is about 6 mm to about 17 mm or less, and is inserted into the cylindrical hole from the second surface side of the plate-shaped portion, which is the opposite surface to the first surface, so that the distal end surface faces the microphone. This makes it possible to accurately measure the performance of the microphone even when the volume is low or when the distance between the sound source and the microphone is short.

The diameter of the cylindrical hole may be approximately 6 mm. This allows the performance of the microphone to be measured without being affected by air viscosity.

A large diameter portion having an inner diameter larger than that of the cylindrical hole is provided on the first surface side of the cylindrical hole, an elastic member is provided on the large diameter portion, and the height of the elastic member is A hole may be provided in the elastic member along the central axis, the hole being higher than the depth of the large diameter portion and having an inner diameter greater than or equal to the inner diameter of the cylindrical hole. Thereby, it is possible to improve the airtightness and sound insulation between the microphone and the sound source.

An acoustic testing device for measuring the characteristics of the first microphone and the second microphone using the first sound source and the second sound source, the sound source including a first sound source and a second sound source, respectively. a transmitting unit that receives a first input signal and a second input signal and transmits sounds from the first sound source and the second sound source, respectively; and an acquisition unit that acquires recorded signals of the first microphone and the second microphone, respectively. a correction unit that corrects the first input signal based on the acquired signal; and a measurement unit that measures characteristics of the first microphone and the second microphone based on the acquired signal, and the plate-shaped The unit has two cylindrical holes, the first microphone and the first sound source are provided in the first cylindrical hole of the two cylindrical holes, and the second cylindrical hole of the two cylindrical holes is provided with the first microphone and the first sound source. the second microphone and the second sound source are provided, and the correction unit determines the distance between the first sound source and the first microphone and the distance between the second sound source and the second microphone based on the acquired signal. and corrects the first input signal based on the estimated result, the measurement unit inputs the first input signal corrected by the correction unit from the transmission unit to the first sound source, and The characteristics of the first microphone and the second microphone may be measured based on an acquisition signal acquired by the acquisition unit when a second input signal is input to the second sound source. This makes it possible to accurately measure the sensitivity and phase characteristics of the microphone.

The first input signal and the second input signal are swept sine waves, and the correction unit transmits the sound from the first sound source and then adjusts the first acquired signal, which is the acquired signal at the first microphone. The amplitude of the first input signal is determined based on the difference between the time to peak and the time from when sound is emitted from the second sound source to the peak of the second acquired signal, which is the acquired signal at the second microphone. and the phase may be corrected. Thereby, the input signal can be corrected so as to eliminate the influence of the amount of change in sound pressure (attenuation amount) due to the difference in distance.

The correction unit converts the first input signal into a frequency domain function, corrects the amplitude and phase of the converted first input signal for each frequency band, and converts the corrected signal into a time domain function. It may be converted to Thereby, the amplitude and phase can be easily corrected.

An acoustic test method according to the present invention is an acoustic test method that measures the characteristics of a first microphone using a first sound source, and measures the characteristics of a second microphone using a second sound source, the method comprising: A first input signal and a second input signal are input to the second sound source, respectively, and sounds are emitted from the first sound source and the second sound source, respectively, and a first acquired signal is acquired by the first microphone and the second microphone. , estimate the distance between the first sound source and the first microphone and the distance between the second sound source and the second microphone based on the first acquired signal, and estimate the distance between the first sound source and the second microphone based on the estimated results. correcting a first input signal, inputting the corrected first input signal to the first sound source, inputting the second input signal to the second sound source, and inputting a second input signal to the first microphone and the second microphone. The method is characterized in that an acquired signal is acquired, and characteristics of the first microphone and the second microphone are measured based on the second acquired signal. This makes it possible to accurately measure the sensitivity and phase characteristics of the microphone.

According to the present invention, the performance of a microphone can be accurately measured even when the volume is low or when the distance between the sound source and the microphone is short.

1 is a diagram showing a schematic configuration of an acoustic testing device 1 according to an embodiment of the present invention. 1 is a perspective view schematically showing an audio device 10. FIG. (A) is a perspective view schematically showing the holding member 20, and (B) is a cross-sectional view of the holding member 20. (A) is a schematic cross-sectional view of the acoustic device 10, (B) is a schematic cross-sectional view of the holding member 20 and the sound source 41, and (C) is a schematic cross-sectional view of the holding member 20 with the acoustic device 10 and the sound source 41. FIG. 3 is a schematic cross-sectional view showing the situation. FIG. 2 is a functional block diagram of the acoustic testing device 1. FIG. 3 is a flowchart showing the flow of measurement processing in the acoustic testing device 1. FIG. (A) is a graph showing an example of the acquired signal C, and (B) is a graph showing an example of the acquired signal D.

EMBODIMENT OF THE INVENTION Hereinafter, embodiments of the acoustic testing apparatus according to the present invention will be described with reference to the drawings.

<First embodiment>
FIG. 1 is a diagram showing a schematic configuration of an acoustic testing apparatus 1 according to an embodiment of the present invention. The acoustic test device 1 measures the performance of the microphones 13 and 14 included in the acoustic device 10, and mainly includes a holding member 20, an information processing section 30, and sound sources 41 and 42.

In this embodiment, the acoustic device 10, the holding member 20, and the sound sources 41, 42 are arranged inside an anechoic box 100 having a sound absorbing layer 101 and a sound insulating layer 102 provided outside the sound absorbing layer 101. Further, the holding member 20 and the sound sources 41 and 42 are surrounded by a sound absorbing layer 101. However, the anechoic box 100 is not essential, and the configuration of the anechoic box 100 is not limited to this.

FIG. 2 is a perspective view schematically showing the acoustic device 10 that is the test object. The audio device 10 is an in-vehicle device that performs so-called hands-free calls such as emergency calls, inputs to a car navigation device installed in the car, and outputs audio from the car navigation device. 12, microphones 13 and 14, and a speaker 15.

The housing 11 is a box-like member with a hollow interior, and microphones 13 and 14 and a speaker 15 are provided inside. Flange portions 12 are provided on both sides of the housing 11 for use in attaching the housing 11 to an automobile. Furthermore, holes 11b, 11c, and 11d are provided in the front surface 11a of the housing 11. Microphones 13 and 14 are exposed through holes 11b and 11c, respectively, and speaker 15 is exposed through hole 11d.

FIG. 3(A) is a perspective view schematically showing the holding member 20, and FIG. 3(B) is a cross-sectional view of the holding member 20 (a cross-sectional view taken along line AA in FIG. 3(A)). be. The holding member 20 is a member that holds the acoustic device 10 during testing.

The holding member 20 is provided with a recess 22 into which the acoustic device 10 is inserted. A plate-shaped portion 21 is provided in the holding member 20 by the recessed portion 22 .

The plate-shaped portion 21 is provided with cylindrical holes 23, 24, and 25 that penetrate in the thickness direction. When the acoustic device 10 is provided inside the recess 22, the first surface 21a of the plate-shaped portion 21 and the front surface 11a of the housing 11 face each other, and the microphones 13 and 14 are provided adjacent to the first surface 21a.

Moreover, when the acoustic device 10 is provided inside the recess 22, the microphones 13 and 14 are provided adjacent to the cylindrical holes 23 and 24, and the speaker 15 is provided adjacent to the cylindrical hole 25. Further, when viewed along the axes of the cylindrical holes 23 and 24, the cylindrical holes 23 and 24 and the microphones 13 and 14 overlap. In other words, the recess 22 has the function of a positioning section that positions the microphones 13 and 14.

Large diameter portions 26 and 27 are provided on the first surface 21a side of the cylindrical holes 23 and 24, respectively. The inner diameters of the large diameter portions 26 and 27 are larger than the inner diameters of the cylindrical holes 23 and 24. Sound sources 41 and 42 are provided in the cylindrical holes 23 and 24, respectively, and elastic members 43 (described in detail later) are provided in the large diameter portions 26 and 27, respectively.

4(A) is a schematic sectional view of the acoustic device 10, FIG. 4(B) is a schematic sectional view of the holding member 20 and the sound source 41, and FIG. 4(C) is a schematic sectional view of the acoustic device 10 and the sound source 41 on the holding member 20. FIG. 4 is a schematic cross-sectional view showing how a sound source 41 is provided. Note that FIG. 4(A) shows only the main parts.

The microphone 13 mainly has a sound hole 13a provided on the front surface and a diaphragm 13b provided inside. Sound reaches the diaphragm 13b via the sound hole 13a,
As the diaphragm 13b vibrates, the microphone 13 records sound. Since the microphone 13 can use already known technology, detailed explanation will be omitted. Furthermore, since the microphones 13 and 14 have the same structure, a description of the microphone 14 will be omitted.

The sound source 41 has a columnar part 41c inserted into the cylindrical hole 23, and emits sound from a distal end surface 41d of the columnar part 41c. The sound source 41 is inserted into the cylindrical hole 23 from the second surface 21b (the surface opposite to the first surface 21a) of the plate-shaped portion 21 so that the distal end surface 41d faces the microphone 13.

The sound source 41 mainly includes a sound hole 41a provided on a distal end surface 41d and a diaphragm 41b provided inside. Sound is generated by the vibration of the diaphragm 41b, and the generated sound is output to the outside via the sound hole 41a. Since the sound source 41 can use already known technology, detailed explanation will be omitted. Furthermore, since the sound sources 41 and 42 have the same structure, a description of the sound source 42 will be omitted.

The elastic member 43 is made of soft urethane foam or the like and has elasticity. The elastic member 43 has a substantially cylindrical shape and has a height higher than the depth of the large diameter portions 26 and 27. Further, the elastic member 43 is provided with a hole 43a along the central axis. The inner diameter of the hole 43a is greater than or equal to the inner diameter of the cylindrical holes 23 and 24. Note that the material of the elastic member 43 is not limited to soft urethane foam, and other elastic materials such as rubber can be used. Further, the elastic member 43 is not limited to a substantially cylindrical shape, and for example, an ear pad of a canal type earphone may be used, but it is desirable that the height is higher than the depth of the large diameter portions 26 and 27.

As shown in FIG. 4C, when the acoustic device 10 is provided inside the recess 22, when viewed along the axis of the cylindrical hole 23, the cylindrical hole 23 and the microphone 13 overlap, and the microphone 13 has an elastic force. The member 43 comes into contact with the microphone 13 and the sound source 41, and the sealing and sound insulation properties between the microphone 13 and the sound source 41 are improved. Similarly, the cylindrical hole 24 and the microphone 14 overlap, the elastic member 43 comes into contact with the microphone 14 (not shown), and the sealing and sound insulation properties between the microphone 14 and the sound source 42 are improved. Note that the elastic member 43 is not essential, and if the elastic member 43 is not used, the large diameter portions 26 and 27 are unnecessary.

Then, when the acoustic device 10 is provided inside the recess 22 and the sound source 41 is provided in the cylindrical hole 23, the microphone 13 and the sound source 41 are connected through a completely closed narrow space (small air chamber). Similarly, when the microphone 14 and the sound source 42 are provided in the cylindrical hole 24, the microphone 14 and the sound source 42 are connected through the small air chamber (not shown). Therefore, the performance of the microphones 13 and 14 can be accurately measured even when the volume is low and is less susceptible to external disturbances.

Further, in a state in which the acoustic device 10 is provided inside the recess 22 and the sound source 41 is provided in the cylindrical hole 23, the sound hole 13a of the microphone 13 and the sound hole 41a of the sound source 41 face each other.

In this embodiment, it is necessary that the small air chamber can be regarded as a free sound field (a range where a point sound source is established without being affected by reflection). For this purpose, the distance s between the diaphragm 13b of the microphone 13 and the diaphragm 41b of the sound source 41 must be shorter than the wavelength of the sound to be measured.

When the speed of sound is v [m/s] and the wavelength is λ [m], the frequency f can be expressed by the following equation (1). Note that the speed of sound is 340 [m/s] (the speed of sound when the air temperature is 15 [° C.]).
f=v÷λ[Hz]=340÷λ[Hz]...(1)

When the distance s is approximately 17 mm or less, the range of frequencies f that can be measured without being affected by reflection is 20,000 [Hz] or less (see formula (2)). When the distance s is approximately 10 mm or less, the range of frequencies f that can be measured without being affected by reflection is 34,000 [Hz] or less (see formula (3)). Similarly, when the distance s is approximately 6 mm or less, the range of frequencies f that can be measured without being affected by reflection is 56,666 [Hz] or less (see formula (4)).
0≦f<(340÷0.017)=0≦f<20,000[Hz]...(2)
0≦f<(340÷0.01)=0≦f<34,000[Hz]...(3)
0≦f<(340÷0.006)=0≦f<56,666[Hz]...(4)

Since the frequencies that humans can hear (audible range) are from 20 Hz to 20,000 Hz, by setting the distance s to approximately 17 mm or less, it is possible to measure frequencies in the audible range using the acoustic testing device 1. . Furthermore, by shortening the distance s to about 6 mm or less, measurements can be performed using the acoustic test device 1 in a range of 56,000 [Hz] or less, which is the frequency (reproduction frequency) that can be emitted by a general sound source. I can do it. Therefore, in the present invention, it is desirable that the distance s be approximately 6 mm or less.

Further, the diameter of the small air chambers (cylindrical holes 23 and 24) is approximately 6 mm. Due to the viscosity of air, a velocity gradient of air occurs near the walls of the cylindrical holes 23, 24 and at the center of the cylindrical holes 23, 24, but if the diameters of the cylindrical holes 23, 24 are small, The influence of viscosity can no longer be ignored. Therefore, in this embodiment, the diameter of the cylindrical holes 23 and 24 is set to approximately 6 mm, which is considered to be unaffected by viscosity.

Returning to the explanation of FIG. The information processing section 30 is mainly realized by a computer system including a control section 31, a storage section 32, and an audio interface (I/F) 33.

The control unit 31 is a program control device such as a CPU, and operates according to a program stored in the storage unit 32. The operation of the control section 31 will be described in detail later.

The storage unit 32 is a memory device, a disk device, or the like, and holds programs executed by the control unit 31. Note that the program may be provided stored in a computer-readable, non-temporary recording medium, and may be copied to the storage unit 32. The storage unit 32 also operates as a work memory for the control unit 31. Furthermore, the storage unit 32 stores various setting information used in the processing of the control unit 31.

The audio I/F 33 converts the digital signal into an analog audio signal and outputs it to the sound sources 41 and 42, and converts the analog signal collected by the microphones 13 and 14 into a digital signal.

Note that the configuration of the information processing unit 30 shown in FIG. 1 is a main configuration described in explaining the features of this embodiment, and does not exclude the configuration included in, for example, a general information processing device.

FIG. 5 is a functional block diagram of the acoustic testing apparatus 1. The control section 31 is functionally configured to include a transmission section 51, an acquisition section 52, a correction section 53, and a measurement section 54. Note that the functional components of the acoustic testing device 1 may be classified into more components depending on the processing content, or one component may execute the processing of a plurality of components.

The transmitter 51 inputs input signals to the sound sources 41 and 42, respectively, and transmits sounds from the sound sources 41 and 42, respectively. The sounds emitted from the sound sources 41 and 42 are impulse sounds, and in this embodiment, a swept sine wave is used. As the swept sine wave, for example, a TSP (Time Stretched Pulse) signal or a Log-SS (Swept Sine) signal can be used. Hereinafter, the input signal input to the sound source 41 will be referred to as input signal A, and the input signal input to the sound source 42 will be referred to as input signal B.

The acquisition unit 52 acquires the acquired signals of the microphones 13 and 14, respectively. Hereinafter, the acquired signal of the microphone 13 will be referred to as an acquired signal C, and the acquired signal of the microphone 14 will be referred to as an acquired signal D.

The correction unit 53 corrects the input signal A or the input signal B based on the acquired signal C and the acquired signal D. In this embodiment, it is assumed that input signal A is corrected. The processing of the correction unit 53 will be described in detail later.

The measurement unit 54 inputs the input signal A corrected by the correction unit 53 to the sound source 41 and inputs the input signal B to the sound source 42, and based on the acquired signal C and the acquired signal D, the microphone Measure characteristics 13 and 14 (sensitivity, phase characteristics, etc.). The processing of the measurement unit 54 will be described in detail later.

FIG. 6 is a flowchart showing the flow of measurement processing in the acoustic testing apparatus 1. First, the transmitter 51 inputs input signals A and B, which are swept sine waves, to the sound sources 41 and 42, respectively (step S10). As a result, sounds are emitted from the sound sources 41 and 42, respectively.

Sounds emitted from sound sources 41 and 42 are input to microphones 13 and 14, respectively. The acquisition unit 52 acquires the acquisition signals C and D and stores them in the storage unit 32 (step S11).

The correction unit 53 estimates the difference Δd between the distance d1 between the sound source 41 and the microphone 13 and the distance d2 between the sound source 42 and the microphone 14 based on the acquired signals C and D stored in the storage unit 32 (step S12). ).

In this embodiment, since the sound sources 41 and 42 and the microphones 13 and 14 are acoustically coupled in small air chambers for measurement, the distance from the sound source is short, and the amount of change in sound pressure (attenuation amount) depending on the distance is measured. is large. Then, a difference occurs between the distance d1 and the distance d2 due to mounting error (positional deviation or inclination) of the microphones 13 and 14, and this causes a difference in the sound input to the microphones 13 and 14. Therefore, in order to accurately measure the performance of the microphones 13 and 14, it is very important to perform a correction such that the distance d1 and the distance d2 are constant.

FIG. 7(A) is a graph showing an example of the acquired signal C, and FIG. 7(B) is a graph showing an example of the acquired signal D. It is assumed that the input signals A and B are simultaneously input to the sound sources 41 and 42, respectively, at time t=0. However, input signals A and B do not have to be input at the same time.

Since the peak of the acquired signal C is located at time t1, the peak position of the acquired signal C (time t1 ) is time T1. Similarly, since the peak of the acquired signal C is located at time t2, the peak position of the acquired signal D is reached after the input signal B is input to the sound source 42 (that is, after the sound source 42 emits the sound). The time until (time t2) is time T2.

If the speed of sound is 340 [m/s], the difference Δd between the distance d1 and the distance d2 is estimated by the following equation (5) based on the arrival time difference Δt between the sounds of the microphones 13 and 14. This ends the process of step S12.
△d[m]=340×△t=340×(T2-T1)...(5)

Returning to the explanation of FIG. 6. Next, the correction unit 53 corrects the input signal A based on the estimation result in step S12 (step S13). The process of step S13 will be explained below.

The distance d1 and the sound pressure level S1 of the sound emitted from the sound source 41 are known in advance and are used as a reference. Based on Δd determined in step S12, the sound pressure level S2 of the sound emitted from the sound source 42 is determined using the following equation (6).
S2 [dB] = S1-20×log ₁₀ (d2/d1)
=S1-20×log ₁₀ ((d1+△d)/d1)...(6)

The amplitude correction coefficient F is determined based on the sound pressure levels S1 and S2 using the following equation (7). Here, S1-S2 is the amount of attenuation of the sound pressure level.
F=10^((S1-S2)/20)...(7)

For example, if the distance d1 is 0.01 [m], Δd is 0.005 [m], and the sound pressure level S1 is 94.0 [dB], the sound pressure level S2 is 90.48 [dB] (=94. 0-20×log ₁₀ (0.015/0.01)), the attenuation amount S1-S2 of the sound pressure level is 3.52 [dB] (=94.0-90.48), and the amplitude correction coefficient F is 1.5 (=10^(3.52/20)).

Next, the input signal y1 input to the sound source 41 is converted into a frequency domain function, and the amplitude and phase of the input signal A converted into the frequency domain function are corrected for each frequency band.

In this embodiment, input signal A is transformed into a frequency domain function using Fourier transform. Hereinafter, the Fourier-transformed input signal will be expressed as input signal A1 (A1=FFT(A)).

In this embodiment, in order to correct the input signal y1 based on the input signal y2 input to the sound source 42, the sign of the amplitude correction coefficient F is inverted and the input signal A1 is By multiplying by , the amplitude of the input signal Y1 is corrected for each frequency band.
A1'=A1×(-F)...(8)

Furthermore, the phase of the input signal A1 is corrected for each frequency band using Equation (9) below. Here, f is the frequency.
A1'=A1×exp(-j×2×π×f×△t)...(9)

Finally, the corrected input signal A1' is converted into a time domain function. In this embodiment, the input signal A1' is returned to a time domain function using inverse Fourier transform. Hereinafter, the input signal subjected to inverse Fourier transform will be expressed as input signal A' (A'=IFFT(A1')). With the above, the process of step S13 is completed.

Next, the measuring unit 54 measures the characteristics of the microphones 13 and 14 using the signals corrected in step S13 (step S14). The transmitter 51 inputs the input signal A' corrected in step S13 to the sound source 41, and inputs the input signal B to the sound source 42. Then, the acquisition unit 52 acquires the acquisition signals of the microphones 13 and 14 when sound is transmitted from the sound sources 41 and 42 based on the input signals A′ and B, and using this acquisition signal, the measurement unit 54 Measure 14 characteristics. With the above, the series of measurement processes performed by the acoustic testing apparatus 1 is completed.

According to this embodiment, the sound sources 41 and 42 and the microphones 13 and 14 are connected by a small air chamber using the cylindrical hole 23, and the distance s between the diaphragm 13b of the microphone 13 and the diaphragm 41b of the sound source 41 is By setting the distance to approximately 6 mm to approximately 17 mm or less, the performance of the microphones 13 and 14 can be accurately measured even when the volume is low or the distance between the sound source and the microphone is short.

Further, according to the present embodiment, when inspecting a plurality of microphones 13 and 14 at the same time, the input is performed so as to eliminate the influence of the amount of change in sound pressure (attenuation amount) due to the difference in distances d1 and d2 due to installation errors, etc. Since the measurement is performed after correcting the signal, the sensitivity and phase characteristics of the microphones 13 and 14 can be accurately measured. For example, when determining the difference between the distances d1 and d2 using image processing or measurement results from a distance sensor, configuration requirements (cameras and sensors) for determining the distance are required, but as in this embodiment, By determining the difference between the distances d1 and d2 using the acquired signals, it is possible to measure the performance of the microphones 13 and 14 with a minimum configuration. Further, in this embodiment, since the input signal is corrected, there is no need to physically adjust the measurement positions of the microphones 13 and 14 and the sound sources 41 and 42, and accurate measurement can be easily performed.

Note that in this embodiment, the performance of the two microphones 13 and 14 was measured simultaneously using two sound sources 41 and 42, respectively, but the acoustic testing apparatus 1 can only test one microphone (microphone 13 or microphone 14). You can also do For example, if only the microphone 13 is to be inspected, the plate-shaped portion 21 only needs to have the cylindrical hole 23, and the cylindrical hole 24 is not necessary. Further, it is sufficient to have the sound source 41, and the sound source 42 is not necessary.

Further, although the present embodiment includes the information processing section 30, the information processing section 30 is not essential. For example, different devices may be used to output the input signal and input the acquired signal. Furthermore, when testing only one microphone, the correction section 53 and the measurement section 54 are not necessary.

Further, in the present embodiment, the holding member 20 is provided with the recess 22 as a positioning portion, but the positioning portion is not limited to the recess 22. For example, when the holding member 20 consists of only a plate-like part corresponding to the plate-like part 21, a plurality of pins and bosses are provided on this plate-like part as positioning parts, and these pins and bosses are used to align the cylindrical hole 23. , 24 and the microphones 13, 14 may be positioned so that they overlap.

Furthermore, in the present embodiment, in the correction process (step S13), the input signal y1 is converted into a frequency domain function, and the amplitude and phase of the input signal y1 converted into the frequency domain function are corrected for each frequency band. , the corrected input signal y1' is converted into a time domain function, but there is no need to correct the input signal y1 converted into a frequency domain function, and the input signal y1, which is a time domain function, is directly corrected. Good too. In this case, it is desirable to correct the acquired signals C and D stored in the storage unit 32 by resampling them at a fine rate. Furthermore, since amplitude and phase correction is easy, it is desirable to correct the input signal y1 converted into a frequency domain function.

Although the embodiment of this invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes, etc. within the scope of the gist of this invention are also included. .

In the present invention, "substantially" is a concept that includes not only strictly the same case, but also errors and deformations to the extent that the sameness is not lost. For example, a substantially cubic shape is not limited to a strictly cubic shape. Furthermore, for example, when simply expressing vertical, coincident, etc., it includes not only cases of strictly vertical, coincident, etc., but also cases of substantially vertical, substantially coincident, etc. Furthermore, in the present invention, "nearby" is a concept that indicates, for example, when it is near A, it is near A and may or may not include A.

1: Acoustic test device 10: Acoustic device 11: Housing 11a: Front surface 11b, 11c, 11d: Hole 12: Flange portions 13, 14: Microphone 13a: Sound hole 13b: Vibration plate 15: Speaker 20: Holding member 21: Plate Shape portion 21a: First surface 21b: Second surface 22: Recessed portions 23, 24, 25: Cylindrical holes 26, 27: Large diameter portion 30: Information processing portion 31: Control portion 32: Storage portion 33: Audio I/F
41 : Sound source 41a : Sound hole 41b : Vibration plate 41c : Column part 41d : Tip surface 42 : Sound source 43 : Elastic member 43a : Hole 51 : Transmission part 52 : Acquisition part 53 : Correction part 54 : Measurement part 100 : Anechoic box 101: Sound absorption layer 102: Sound insulation layer

Claims (6)

An acoustic testing device for measuring characteristics of a microphone,
a holding member having a plate-like portion provided with a cylindrical hole penetrating in the thickness direction;
a sound source that has a columnar part inserted into the cylindrical hole and emits sound from the tip surface of the columnar part;
Equipped with
The microphone is provided adjacent to the first surface of the plate-shaped portion,
The holding member has a positioning part that arranges the microphone so that the cylindrical hole and the microphone overlap when viewed along the axis of the cylindrical hole,
The columnar portion has a second surface opposite to the first surface of the plate-like portion such that the distance between the diaphragm of the microphone and the diaphragm of the sound source is approximately 6 mm to approximately 17 mm. the distal end face is inserted into the cylindrical hole from the side so as to face the microphone;
A large diameter portion having an inner diameter larger than that of the cylindrical hole is provided on the first surface side of the cylindrical hole,
The large diameter portion is provided with an elastic member,
The height of the elastic member is higher than the depth of the large diameter portion,
The elastic member is provided with a hole having an inner diameter larger than or equal to the inner diameter of the cylindrical hole along the central axis.
An acoustic testing device characterized by: The acoustic testing device according to claim 1, wherein the diameter of the cylindrical hole is approximately 6 mm. An acoustic testing device that measures characteristics of a first microphone and a second microphone, using a first sound source and a second sound source, which are the sound sources,
a transmitter that inputs a first input signal and a second input signal to the first sound source and the second sound source, respectively, and transmits sounds from the first sound source and the second sound source, respectively;
an acquisition unit that acquires acquisition signals of the first microphone and the second microphone, respectively;
a correction unit that corrects the first input signal based on the acquired signal;
a measurement unit that measures characteristics of the first microphone and the second microphone based on the acquired signal;
Equipped with
The plate-shaped portion has two of the cylindrical holes,
The first microphone and the first sound source are provided in a first cylindrical hole of the two cylindrical holes, and the second microphone and the second sound source are provided in a second cylindrical hole of the two cylindrical holes. is,
The correction unit estimates the distance between the first sound source and the first microphone and the distance between the second sound source and the second microphone based on the acquired signal, and estimates the distance between the first sound source and the second microphone based on the estimated result. Correct the input signal,
The measurement unit inputs the first input signal corrected by the correction unit from the transmission unit to the first sound source, and the measurement unit inputs the second input signal corrected by the correction unit to the second sound source. The acoustic testing device according to claim 1 or 2, wherein the characteristics of the first microphone and the second microphone are measured based on the acquired signals. the first input signal and the second input signal are swept sine waves;
The correction unit is configured to calculate a time period from when a sound is transmitted from the first sound source to a peak of the first acquired signal, which is the acquired signal at the first microphone, and from when the sound is transmitted from the second sound source to the peak of the first acquired signal, which is the acquired signal at the first microphone. The acoustic testing device according to claim 3 , wherein the amplitude and phase of the first input signal are corrected based on the difference between the time to the peak of the second acquired signal, which is the acquired signal in two microphones. . The correction unit converts the first input signal into a frequency domain function, corrects the amplitude and phase of the converted first input signal for each frequency band, and converts the corrected signal into a time domain function. The acoustic testing device according to claim 4 , characterized in that: An acoustic test method that measures the characteristics of a first microphone using a first sound source, and measures the characteristics of a second microphone using a second sound source, the method comprising:
inputting a first input signal and a second input signal to the first sound source and the second sound source, respectively, and emitting sound from the first sound source and the second sound source, respectively;
acquiring a first acquisition signal with the first microphone and the second microphone;
Estimating the distance between the first sound source and the first microphone and the distance between the second sound source and the second microphone based on the first acquired signal, and calculating the first input signal based on the estimated results. Correct,
inputting the corrected first input signal to the first sound source; inputting the second input signal to the second sound source;
acquiring a second acquisition signal with the first microphone and the second microphone;
An acoustic testing method, comprising: measuring characteristics of the first microphone and the second microphone based on the second acquired signal.

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