CN111919454B

CN111919454B - Microphone array and acoustic analysis system

Info

Publication number: CN111919454B
Application number: CN201980022562.7A
Authority: CN
Inventors: 高桥拓也; 丰岛直穗子
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2018-03-28
Filing date: 2019-03-27
Publication date: 2022-12-02
Anticipated expiration: 2039-03-27
Also published as: WO2019189484A1; CN111919454A

Abstract

The present invention provides a microphone array (1) comprising: a plurality of MEMS microphones; a plurality of microphone substrates on which a plurality of MEMS microphones are mounted one by one, respectively; and a support member that detachably supports each of the plurality of microphone substrates. The microphone substrate can be disposed so as to be perpendicular or substantially perpendicular to a measurement surface on which the plurality of MEMS microphones are disposed.

Description

Microphone array and acoustic analysis system

Technical Field

The present invention relates to a microphone array and an acoustic analysis system.

Background

In recent years, since there is an increasing demand for reduction in noise of products, it is required to measure and analyze the spatial distribution of a sound field.

Patent document 1 discloses a sound pressure distribution analysis system using a microphone array in which a plurality of microphones are arranged in a grid pattern and sounds are detected at a plurality of positions. The sound pressure distribution analysis system includes amplifiers capable of amplifying multichannel signals, and the amplifiers amplify the respective sound signals of the microphones and output the amplified sound signals to the analysis terminal. The analysis terminal A/D converts the audio signal inputted from the amplifier and records the converted signal as a time waveform.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2005-91272

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional microphone array described above, a condenser microphone or a moving-coil microphone is used, and when the microphones are arranged at an interval of 1cm or less, for example, the measurement surface of the microphone array has a compact structure, and it is difficult to analyze the acoustic hologram due to the influence of the reflected sound from the microphone array.

Therefore, a microphone array using a small-sized MEMS (Micro-Electrical-Mechanical Systems) microphone capable of surface mounting on a substrate is known. As such a MEMS microphone array, a method is known in which a plurality of MEMS microphones are mounted on a lattice-shaped substrate and the substrate itself constitutes a microphone array.

However, in the MEMS microphone array, generally, a plurality of MEMS microphones are surface-mounted on one substrate, and if any defect occurs in one of the plurality of MEMS microphones, the substrate needs to be repaired or replaced in conjunction with the defect, which increases the cost.

Therefore, an object of the present invention is to provide a microphone array and an acoustic analysis system in which a plurality of MEMS microphones can be easily replaced in each unit.

Means for solving the problems

In order to solve the above problem, a microphone array according to an aspect of the present invention includes: a plurality of MEMS microphones; a plurality of microphone substrates on which the plurality of MEMS microphones are mounted one by one, respectively; and a support member configured to detachably support each of the plurality of microphone substrates.

An acoustic analysis system according to an aspect of the present invention includes an acoustic analysis device that analyzes a signal input from each of the plurality of MEMS microphones and detects a physical quantity indicating a sound characteristic.

The effects of the invention are as follows.

According to one aspect of the present invention, since the plurality of MEMS microphones are mounted on the separate microphone substrates, respectively, the plurality of MEMS microphones can be easily replaced in each unit.

Drawings

Fig. 1 is an overall view of a microphone array in the present embodiment.

Fig. 2 is a diagram showing the structure of a microphone.

Fig. 3 is a diagram showing the structure of the first support body.

Fig. 4 is a diagram illustrating the structure of the second support.

Fig. 5 is a diagram showing an example of connection between the microphone and the control board.

Fig. 6 is a diagram showing an example of an acoustic analysis system.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention.

Fig. 1 is an overall view of a microphone array 1 in the present embodiment.

The microphone array 1 according to the present embodiment can be used in an acoustic analysis system for analyzing a measurement target sound from a measurement target (sound source) by using a near-field acoustic holography method. In the near-field acoustic holography, a microphone array in which a plurality of microphones are arranged in a grid pattern is used by measuring a sound pressure distribution on a measurement plane which is close to a sound source plane and parallel to the sound source plane.

As shown in fig. 1, the microphone array 1 includes a plurality of first supports 10, a plurality of second supports 20, and a plurality of microphones mc. Each of the plurality of microphones mc is a MEMS (Micro-Electrical-Mechanical Systems) microphone.

The first support 10 is a member having a first direction (x direction) as a longitudinal direction. In the present embodiment, the microphone array 1 includes M (eight in fig. 1) first supports 10.

The second supports 20 are each members having a second direction (z direction) perpendicular to the first direction (x direction) as a longitudinal direction. In the present embodiment, the microphone array 1 includes two second supports 20. The two second supports 20 detachably support both ends of the M first supports 10, respectively.

The first support 10 supports N (eight in fig. 1) microphones mc, respectively, in a state of being arranged at constant intervals d in the x direction. The first supports 10 are arranged in parallel at a constant interval d in the z direction. In each first support 10, the position of the microphone mc in the x direction is the same. That is, M × N microphones mc are arranged in a grid pattern in the xz direction by M first supporting members 10.

In fig. 1, the xz plane is a plane parallel to the measurement plane of the microphones mc in which the microphone array 1 is arranged in a grid pattern, and is a plane parallel to the sound source plane of the object to be measured. The microphone array 1 is disposed in a state where the measurement surface is separated from the sound source surface of the object by a predetermined distance in the y direction. For example, the microphone array 1 is arranged such that the distance between the measurement plane and the sound source plane in the y direction is within 1 cm.

The first support 10 and the second support 20 constitute a support member for supporting the plurality of microphones mc. The support member is not limited to the structure shown in fig. 1. The support member may include a plurality of first supports 10 and at least one second support 20. For example, the second support 20 may support only one end of the first support 10, or may support a position other than the end of the first support 10.

The microphone mc is a nondirectional MEMS microphone capable of receiving sound from all directions.

As shown in fig. 2, the microphone mc incorporates an acoustic transducer (MEMS chip) and an amplifier using MEMS technology, and is mounted on the surface of a microphone substrate 31 which is a small substrate. The microphone mc converts sound (sound pressure) into an electric signal by an acoustic transducer, and amplifies and outputs the converted electric signal by an amplifier. In the case where the microphone mc is a digital microphone, the microphone mc further incorporates an a/D converter, and can convert an analog signal amplified by an amplifier into a digital signal and output the digital signal.

In the present embodiment, the plurality of microphones mc are individually mounted on the individual microphone substrates 31, and the support member detachably supports each of the plurality of microphone substrates 31. Specifically, the M first supports 10 support the N microphone substrates 31 at constant intervals d in the x direction, respectively. Each microphone substrate 31 is detachably mounted on the first support body 10 through a mounting hole 31a formed in the microphone substrate 31.

The microphone substrate 31 is provided with a connector portion 32. The connector portion 32 is connected to a connector portion 41a of a cable 41 for connecting the microphone mc to a control board 40 (see fig. 5) for controlling the microphone mc. That is, the microphone mc is connected to the control board 40 via the cable 41.

Fig. 3 is a configuration diagram showing a part of the first support 10 in the present embodiment. Fig. 3 shows a state in which the cable 41 and the connector portion 41a in fig. 2 are removed from the microphone substrate 31.

As shown in fig. 3, the first support body 10 includes a plurality of mounting holes 11 to which the microphone substrates 31 can be mounted at arbitrary intervals in the x direction. The plurality of mounting holes 11 have a shape capable of mounting the microphone substrate 31, and are formed at equal intervals in the x direction. The N microphone substrates 31 are attached to the N attachment holes 11 of one first support body 10, respectively, so that the microphones mc can be arranged at a constant interval d in the x direction. The microphone substrate 31 is detachable from the first support body 10, and the distance d between the microphones mc in the x direction can be arbitrarily changed. Here, the mounting holes 11 are formed at intervals of, for example, about 3mm in the x direction, and the interval d in the x direction can be changed from about 3mm to about 20mm, for example.

The first support 10 has a plate-like shape having a length in the z direction shorter than a length in the y direction orthogonal to the measurement surface. That is, the first support 10 extends perpendicularly to the measurement surface. The microphone substrate 31 is mounted parallel to a surface perpendicular to the measurement surface of the first support body 10. Thus, the mounting surface of the microphone mc is perpendicular to the measurement surface.

The microphone substrate 31 is attached to the first support 10 such that the microphone mc is positioned closer to the object to be measured in the y direction, i.e., closer to the sound source surface 2 a. More specifically, the microphone mc is disposed to protrude from an end surface of the first support 10 on the measurement object side (on the sound source surface 2a side) toward the measurement object side (on the sound source surface 2a side) in the y direction. That is, the first support 10 and the second support 20 are disposed on the opposite side of the sound source surface 2a with respect to the measurement surface so as not to block the sound to be measured from the sound source.

In a state where the cable 41 is connected to the microphone substrate 31, the cable 41 extends from the side of the microphone substrate 31 that is away from the object to be measured (sound source surface 2 a) toward the control substrate 40 in the y direction.

Fig. 4 is a diagram showing the structure of the second support body 20 in the present embodiment.

As shown in fig. 4, the second support body 20 includes a plurality of mounting grooves (concave portions) 21 into which the first support body 10 can be inserted at arbitrary intervals in the z direction. The plurality of mounting grooves 21 have a shape into which the first support body 10 can be inserted, and are formed at equal intervals in the z direction. The M first support bodies 10 are fixed by inserting end portions thereof into the mounting grooves 21 of the second support body 20 so as to be arranged at a constant interval d in the z direction. The first support 10 is detachable from the second support 20, and the interval d in the z direction of the first support 10 can be arbitrarily changed. Here, the mounting grooves 21 are formed at intervals of, for example, about 3mm in the z direction, and the interval d in the z direction can be changed from about 3mm to about 20mm, for example.

Fig. 5 is a diagram showing an example of connection between the microphone mc and the control board 40.

The control board 40 can perform control related to recording of the plurality of microphones mc. One ends of a plurality of cables 41 are connected to the control board 40, and the other ends of the plurality of cables 41 are connected to the microphone mc.

The M × N microphones mc included in the microphone array 1 may be connected to one control board 40 and controlled by one microphone control unit, or each of a predetermined number of microphones mc may be connected to different control boards 40 and controlled by a plurality of microphone control units. For example, one control board 40 may be connected to N microphones mc supported by one first support 10, and one microphone controller may perform control related to recording of the N microphones mc. In this case, a control unit may be further provided that controls the M microphone control units corresponding to the M first supports 10, respectively.

As described above, the microphone array 1 in the present embodiment has the following structure: the present invention is provided with a plurality of microphones (MEMS microphones) mc and a plurality of microphone substrates 31 on which the plurality of microphones mc are individually mounted, and the ladder-shaped support member provided with the first support body 10 and the second support body 20 detachably supports the microphone substrates 31.

In this way, since the plurality of microphones mc are mounted on the individual microphone substrates 31, the plurality of microphones mc can be easily replaced in each unit. Further, since the plurality of microphones mc are supported by the ladder-shaped support member, it is possible to suppress the sound from being reflected by the support member when the microphone array 1 is disposed in proximity to the object to be measured, compared to a configuration in which the plurality of microphones are supported by a lattice-shaped support member, for example. As a result, the reflected sound from the microphone array 1 can be suppressed from adversely affecting the acoustic analysis result.

The first support body 10 has a plurality of mounting holes 11 to which the microphone substrates 31 can be mounted at arbitrary intervals, and can support the plurality of microphone substrates 31 at arbitrary constant intervals in the x direction. The second support body 20 has a plurality of mounting grooves 21 into which the first support bodies 10 can be inserted at arbitrary intervals, and the plurality of first support bodies 10 can be arranged in parallel at arbitrary constant intervals in the z direction.

With this configuration, the degree of freedom in the arrangement of the microphones mc can be increased, and the positional relationship (the distance d) between the microphones mc can be freely adjusted according to the size of the object to be measured. Therefore, it is not necessary to prepare a microphone array corresponding to each object to be measured, and the corresponding cost can be reduced. Further, the interval d can be easily adjusted by a relatively simple configuration.

In general, a microphone array using MEMS microphones has a structure in which a plurality of MEMS microphones are surface-mounted on one substrate. Therefore, if any defect occurs in one of the MEMS microphones, the substrate must be repaired or replaced. In contrast, in the present embodiment, since the plurality of MEMS microphones are surface-mounted on the microphone substrate one by one, as described above, when any defect occurs in one of the plurality of MEMS microphones, only the microphone substrate on which the MEMS microphone having the defect is mounted may be repaired or replaced.

In addition, a method is known in which a plurality of MEMS microphones are mounted on a lattice-shaped substrate and a microphone array is configured by the substrate itself. However, in this case, the intervals of the lattice shape cannot be changed according to the size of the object to be measured, and it is necessary to create a microphone array from the substrate for each object to be measured. In contrast, in the present embodiment, as described above, the plurality of MEMS microphones are mounted on separate microphone substrates, and the plurality of microphone substrates can be arranged at arbitrary intervals. Therefore, the object to be measured of various sizes can be handled by one microphone array.

However, when the object to be measured is small, the grid interval of the microphone may be set to, for example, 1cm or less. In the case of such a small microphone array, when the measurement surface of the microphone array has a compact structure, the microphone array is seen as a wall portion and the sound is reflected, and the sound is reverberated between the object and the microphone array. In the case where the sound in the steady state is desired to be measured, the reverberant sound overlaps with the sound desired to be measured, thereby hindering accurate measurement. As a result, it is difficult to perform acoustic analysis using the microphone array.

In contrast, in the present embodiment, the microphone substrate 31 on which the microphone mc is mounted is arranged perpendicular to the measurement surface. Therefore, even if the lattice spacing d of the microphones mc is narrow, the measurement surface of the microphone array 1 can be prevented from being a tight structure, and the occurrence of the reflected sound can be suppressed.

Here, the microphone mc can be a non-directional microphone. Thus, sound collection by the microphone mc can be appropriately performed regardless of the posture of the microphone board 31. The microphone mc can be a MEMS microphone. By using the MEMS microphone in this way, a microphone array capable of realizing near-field acoustic holography suitable for a small-sized object to be analyzed can be obtained.

Further, by forming the first support 10 in a shape extending perpendicularly to the measurement surface, the first support 10 can be prevented from becoming a wall portion, and the generation of reflected sound can be suppressed. Further, by mounting the microphone substrate 31 on the surface perpendicular to the measurement surface of the first supporting body 10, the microphone substrate 31 can be easily and appropriately arranged perpendicular to the measurement surface. Also, the postures of the plurality of microphone substrates 31 can be easily aligned vertically.

Further, in the microphone substrate 31, the microphone mc is mounted at a position close to the object to be measured. This allows the microphone mc to appropriately pick up sound. In this case, by disposing the microphone mc so as to protrude from the end surface of the first support 10 on the measurement object side toward the measurement object side, it is possible to more appropriately pick up sound.

In addition, since the cable 41 extends from the side of the microphone substrate 31 which is far from the object to be measured to the control substrate 40, the cable 41 does not hinder sound pickup.

As described above, the microphone array 1 according to the present embodiment can easily adjust the positional relationship between the microphones mc according to the size of the object to be measured, and can appropriately measure the sound to be measured from the object to be measured. Further, even when the object to be measured is small and the space between the squares of the microphone mc is narrow, the structure can be made such that the sound to be measured from the object to be measured is not blocked. Therefore, the acoustic measurement from various small-sized objects can be accurately measured by the single microphone array 1.

Fig. 6 is a configuration example of an acoustic analysis system 1000 including the microphone array 1 in the present embodiment.

The acoustic analysis system 1000 includes the microphone array 1, the acoustic analysis device 100, and the display device 200. The acoustic analysis device 100 analyzes signals input from the plurality of microphones mc, and detects a physical quantity representing a sound characteristic. In the acoustic analysis system 100, the microphone array 1 is disposed close to the object 2 so that the measurement surface is parallel to the sound source surface 2a of the object 2.

The acoustic analysis device 100 includes a signal processing unit 101, an analysis processing unit 102, and a storage unit 103. The signal processing unit 101 performs predetermined signal processing on the signal from each microphone mc of the microphone array 1 to obtain a signal used for acoustic analysis. The signal processing may include a process of synchronizing signals of M × N microphones mc included in the microphone array 1.

The analysis processing unit 102 analyzes the signal processed by the signal processing unit 101 and detects a physical quantity indicating a sound characteristic. Here, the physical quantity indicating the sound characteristic includes a sound pressure distribution, a particle velocity distribution, and the like. Then, the analysis processing unit 102 generates an image corresponding to the physical quantity representing the sound feature, and performs display control for displaying the image on the display device 200.

The storage unit 103 stores analysis results and the like of the analysis processing unit 102.

The display device 200 includes a monitor such as a liquid crystal display, and displays the image as a result of analysis by the acoustic analysis device 100.

As described above, the acoustic analysis system 1000 according to the present embodiment includes the microphone array 1 for near-field acoustic holography in which the lattice spacing of the microphones mc is small and variable, and can perform accurate measurement and acoustic analysis on a small-sized object to be measured.

The acoustic analysis system 1000 including the M × N microphone array may include, for example, M microphone array modules for performing recording-related control of the N microphones mc, and a control unit for controlling the M microphone array modules. In this case, the microphone array module receives signals of the N microphones mc and transmits the received signals of the N microphones mc to the control section. Then, the control unit receives the signals of the microphones mc from the M microphone array modules, respectively, and processes the signals into signals used for acoustic analysis.

At this time, the control unit may perform a process of aligning the phases of the signals of the microphones mc received from the respective microphone array modules. Note that synchronization of the N microphones mc included in one microphone array module is electrical synchronization. Here, the N microphones mc provided in one microphone array module can be the N microphones mc supported by one first support body 10.

In this case, the number of microphones mc constituting the microphone array 1 can be easily increased by adding the microphone array module. Therefore, the size of the microphone array 1 can be increased in accordance with the size of the object to be measured, and the spatial resolution can be improved.

(modification example)

In the above-described embodiment, the case where the microphone substrate 31 is disposed so as to be perpendicular to the measurement surface on which the plurality of microphones mc are disposed has been described, but the microphone substrate 31 may be disposed so as to be perpendicular or substantially perpendicular to the measurement surface. That is, the microphone substrate 31 may be disposed to be inclined with respect to the measurement surface. In this case, the effect of suppressing the influence of the reflected sound generated by the microphone array 1 can be obtained.

Further, a plurality of M × N microphone arrays 1 in the above embodiment may be connected to form a large microphone array.

Description of the symbols

1-microphone array, 2-object to be measured (sound source), 2 a-sound source surface, 10-first support, 11-mounting hole, 20-second support, 21-mounting groove (concave), 31-microphone substrate, 40-control substrate, 41-cable, 100-acoustic analysis device, 200-display device, 1000-acoustic analysis system, mc-microphone.

Claims

1. A microphone array is characterized by comprising:

a plurality of MEMS microphones;

a plurality of microphone substrates on which the plurality of MEMS microphones are mounted, respectively; and

a support member configured to detachably support each of the plurality of microphone substrates,

the MEMS microphone is internally provided with an MEMS chip and an amplifier,

the surface of the first support body on which the microphone substrate is mounted extends perpendicularly to the measurement surface.

2. Microphone array according to claim 1,

the microphone substrate is disposed perpendicular to a measurement surface on which the plurality of MEMS microphones are disposed.

3. Microphone array according to claim 2,

each of the MEMS microphones is a nondirectional MEMS microphone.

4. Microphone array according to one of claims 1 to 3,

the support member includes:

a plurality of first supports that detachably support the plurality of microphone boards; and

at least one second support body which detachably supports the plurality of first support bodies,

the first support body can support the microphone substrate at an arbitrary constant interval in a first direction,

and can be arranged in parallel at an arbitrary constant interval in a second direction orthogonal to the first direction.

5. Microphone array according to claim 4,

the first support body has a plurality of mounting holes to which the microphone substrate can be mounted at arbitrary intervals.

6. Microphone array according to claim 5,

the second support body has a plurality of mounting grooves into which the first support body can be inserted at arbitrary intervals.

7. Microphone array according to claim 5 or 6,

the length of the first support in the second direction is shorter than the length in a direction perpendicular to a measurement surface on which the plurality of MEMS microphones are arranged.

8. Microphone array according to claim 7,

the microphone substrate is attached to a surface of the first support body perpendicular to the measurement surface.

9. Microphone array according to claim 5 or 6,

the MEMS microphone is disposed so as to protrude from an end surface of the first support on the object side toward the object side.

10. Microphone array as claimed in any of claims 1 to 3,

the MEMS microphone is mounted on the microphone substrate at a position close to the object to be measured.

11. Microphone array according to claim 10,

the MEMS microphone is connected with a control substrate for controlling the MEMS microphone through a cable,

the cable extends from a side of the microphone substrate that is away from the object to be measured to the control substrate.

12. Microphone array according to claim 1,

the microphone substrate, which is a small-sized substrate, is provided with a connector portion, the control substrate is connected with a plurality of cables, and the connector portions of the plurality of cables are connected with the MEMS microphones, respectively.

13. Microphone array according to claim 1,

the MEMS chip is an acoustic transducer.

14. Microphone array according to claim 1,

the interval of the first direction of the microphones can be changed between 3mm and 20mm,

the interval of the second direction of the microphones can be changed between 3mm and 20 mm.

15. An acoustic analysis system comprising:

a microphone array as claimed in any one of claims 1 to 3; and

and an acoustic analysis device that analyzes a signal input from each of the plurality of MEMS microphones and detects a physical quantity indicating a sound characteristic.