WO2022172401A1

WO2022172401A1 - Design device, design method, and program

Info

Publication number: WO2022172401A1
Application number: PCT/JP2021/005267
Authority: WO
Inventors: 賢一野口; 達也加古
Original assignee: 日本電信電話株式会社
Priority date: 2021-02-12
Filing date: 2021-02-12
Publication date: 2022-08-18

Abstract

Provided is a design device for designing a microphone array by assessing the directionality performance improvement amounts of various shapes of recesses without actually producing a microphone array. This design device comprises: a storage unit that stores the property of a predetermined acoustic signal and a predetermined directionality, and the shape of a recess suitable for the property of the predetermined acoustic signal and the predetermined directionality; an input unit that receives an input of the property of an acoustic signal to be collected and a desired directionality; and a design unit that designs the shape of a recess portion suitable for the desired directionality that has been inputted and the inputted property of the acoustic signal to be collected, by referring to the storage unit.

Description

DESIGN DEVICE, DESIGN METHOD, AND PROGRAM

The present invention relates to a microphone array design method for microphone array processing that emphasizes acoustic signals such as voices and music arriving from arbitrary directions, centering on the microphone array.

Patent Document 1 is known as a method for emphasizing acoustic signals such as voices and music arriving from arbitrary directions centering on a microphone array.

In Patent Document 1, a plurality of recesses are provided from the sphere that forms the base to the inside, and microphones are arranged on the bottom of each recess to form a microphone array. With this arrangement, the difference in transfer characteristics between the sound source and the microphones is increased, and directivity performance is improved when performing beamforming that emphasizes acoustic signals in arbitrary directions by microphone array processing. make improvements.

JP 2020-88561 A

However, in Non-Patent Document 1, the amount of improvement in directivity performance, particularly the sharpness of directivity, due to various shapes of recesses is unknown. In addition, although it is possible to emphasize an acoustic signal from any direction, there may be a difference in directivity performance for each direction of arrival, resulting in a difference in the amount of emphasis. not considered.

In the present invention, without actually creating a microphone array, it is possible to evaluate the amount of directivity performance improvement in various concave shapes and form directivity that increases the sensitivity in the target direction specified by the user. An object of the present invention is to provide a design device, a design method, and a program for designing a microphone array.

In order to solve the above problems, according to one aspect of the present invention, a design device includes: a base having at least N recesses on its surface, where N is an integer of 2 or more; A device for designing a microphone array having N microphones installed one by one on the bottom side. The design device includes a storage unit that stores a predetermined property and predetermined directivity of an acoustic signal, a shape of a concave portion suitable for the predetermined property and predetermined directivity of the acoustic signal, and a property of the acoustic signal to be collected. and an input unit that receives input of desired directivity, and a design unit that refers to the storage unit and designs the shape of the recess suitable for the property of the input acoustic signal to be collected and the desired directivity. .

According to the present invention, it is possible to design a microphone array by evaluating the amount of directivity performance improvement in various concave shapes without actually manufacturing the microphone array.

FIG. 2 is a functional block diagram of the design device according to the first embodiment; FIG. 4 is a diagram showing an example of the processing flow of the design device according to the first embodiment; The figure which shows the example of a microphone arrangement, a base, and a sound source position. FIG. 4A is a plan view and a cross-sectional view of an example of a recess having a conical horn shape; FIG. 4 is a diagram for explaining the shape of a recess; FIG. 4 is a diagram showing the relationship between the shape of a recess and parameters; FIG. 10 is a plan view and a cross-sectional view of an example of a recess having a parabolic horn shape; FIG. 4 is a diagram for explaining the shape of a recess; FIG. 4 is a diagram showing the relationship between the shape of a recess and parameters; FIG. 10 is a plan view and a cross-sectional view of an example of a recess having an exponential horn shape; FIG. 4 is a diagram for explaining the shape of a recess; FIG. 4 is a diagram showing the relationship between the shape of a recess and parameters; FIG. 4 is a diagram showing directivity characteristics of a microphone array (without a base) consisting only of microphones; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; FIG. 4 is a diagram showing the directional characteristics of a microphone array composed of microphones and recesses having a conical horn shape; The shape of the recess indicates the 'n' dB beamwidth of the conical horn. The shape of the recess indicates the 'n' dB beamwidth of the parabolic horn. The shape of the recess indicates the 'n' dB beamwidth of the exponential horn. Figure showing the 'n' dB beamwidth for the optimal parameters for each horn. The shape of the recess shows the 'n' dB beam average deflection of the conical horn. The shape of the recess shows the 'n' dB beam average deflection of the parabolic horn. The shape of the recess indicates the 'n' dB beam average deflection of the exponential horn. 'n' dB beam average bias for beamwidth-sharp parameter for each horn. The figure which shows the structural example of the computer which applies this method.

Embodiments of the present invention will be described below. It should be noted that in the drawings used for the following description, the same reference numerals are given to components having the same functions and steps that perform the same processing, and redundant description will be omitted. In the following description, the processing performed for each element of a vector or matrix is applied to all elements of the vector or matrix unless otherwise specified.

<First Embodiment>
FIG. 1 is a functional block diagram of a design device 100 according to the first embodiment, and FIG. 2 shows its processing flow.

The design device 100 includes an evaluation section 110 , a storage section 120 , an input section 130 , a design section 140 and an output section 150 .

The design apparatus 100 receives a simulation result x, which will be described later, as an input, evaluates the directivity characteristics for each shape of the concave portion for each frequency, and stores the evaluation result y in the storage unit 120 .

The design apparatus 100 receives input of properties of an acoustic signal desired to be collected by the user and desired directivity via the input unit 130, refers to the storage unit 120, and receives properties and characteristics of the input acoustic signal desired to be collected. A concave shape suitable for desired directivity is designed, and information z about the designed shape is output via the output unit 150 .

A design device is, for example, a special device configured by loading a special program into a publicly known or dedicated computer having a central processing unit (CPU: Central Processing Unit), a main memory (RAM: Random Access Memory), etc. is. The design device executes each process under the control of, for example, a central processing unit. Data input to the design device and data obtained in each process are stored, for example, in a main memory device, and the data stored in the main memory device are read out to the central processing unit as necessary and used for other purposes. used for processing. At least a part of each processing unit of the design apparatus may be configured by hardware such as an integrated circuit. Each storage unit provided in the design apparatus can be configured by, for example, a main storage device such as RAM (Random Access Memory), or middleware such as a relational database or key-value store. However, each storage unit does not necessarily have to be provided inside the design device. It is good also as a structure prepared for.

First, the input simulation result x will be explained. The following processing is performed to obtain the simulation result x.

(1) Assuming that the microphone array 1 described later exists, the impulse response from the sound source is obtained by simulation.

(2) Using the acquired impulse responses, calculate filters that perform beamforming with the directions of the M sound sources as the target directions.

(3) Through simulation, filter the impulse responses arriving from each microphone from M sound sources, and obtain the signal after filtering. The filtered signal corresponds to the simulation result x.

Each process will be explained below.

<Acquisition of impulse response>
FDTD (Finite Difference Time Domain) simulation is performed to simulate the reflection and diffraction of the sound pickup device and obtain the impulse response (transmission characteristics). FIG. 3 is a diagram for explaining simulation conditions. The simulated microphone array 1 has N microphones 12-n (indicated by black circles in FIG. 3). Note that N is any integer of 2 or more. An impulse response reaching each microphone 12-n is calculated by simulation from the positions of 36 sound sources s (indicated by white circles in FIG. 3). Let n=1,2,…,N.

The analysis area size is 2.8×2.8 m ² and the surrounding boundary condition is 20 PML (Perfectly Matched Layer). Let the center position of the microphone array 1 be the center of the analysis area. In the simulation, the grid size (Δx, Δy, Δz) of the x-axis, y-axis, and z-axis is set to 0.01 m, the reflection condition of the base 11 is set to a rigid body, a Gaussian pulse is applied to the sound source s, and the time step size is set to Calculate the pressure fluctuation for a time length of Δt=10 ^-5 [s].

The details of the microphone array 1 will be described below.

<Microphone array 1>
The microphone array 1 has a base 11 having N recesses 111-n on its surface, and N microphones 12-n placed one by one on the inner bottom surface of each recess 111-n. In the present embodiment, a two-dimensional study is performed, and a microphone array is assumed in which N microphones are arranged in a circle on the same plane with a predetermined interval from each other. However, a similar simulation can be performed in three dimensions. It can also be applied to spherically arranged microphone arrays.

Fig. 3 shows an example of microphone placement, base, and sound source position.

In the example of FIG. 3, the number of microphones is N=4, and the four microphones 12-n are arranged at positions of θ _m =0°, 90°, 180°, 270° on a circle of radius r _m . However, n=1,2,3,4.

The base 11 consists of a substantially spherical body with a radius of r _a =0.2 m. In FIG. 3, in order to examine two dimensions, it is assumed that four recesses 111-n are formed so that the centers of the four recesses 111-n are positioned on the same plane (the xy plane in this example). . Further, in FIG. 3, four microphones 12-n are arranged on the inner wall surfaces of the four concave portions 111-n, and the four microphones 12-n are arranged so that the sound collecting parts of the microphones 12-n are positioned on the same plane. are placed. Note that the sound collector is a part that includes a mechanism (for example, a diaphragm or metal foil) that converts air vibration of sound into an electric signal. The sound collecting section is provided, for example, on one end side of the microphone 12-n.

It is desirable that the four recesses 111-n are arranged at predetermined intervals from each other, and that the shapes of the four recesses 111-n are substantially the same (the same or substantially the same). As a result, it is possible to reduce sound pickup variations depending on the sound arrival direction. A substantially spherical body means a three-dimensional object having a shape close to a sphere although it is not strictly a sphere (substantially a sphere). An example of a substantially spherical body is a three-dimensional body in which the surface shape of the portion other than the concave portion 111-n matches or substantially matches the surface shape of the sphere.

Although FIG. 3 shows an example of N=4, this does not limit the present invention. The base 11 is made of, for example, a material that sufficiently reflects sound (for example, synthetic resin, metal, wood, etc.).

36 positions of the sound source _{s are assumed, and the 36 sound source positions are arranged at positions of θ s} ₌ 0°, 10°, 20°, . s=1,2,...,36.

<Example 1 of the shape of the concave portion 111-n>
The shape of the recess 111-n may be a conical horn.

(A) of FIG. 4 is a plan view of an example of a recess 111-n having a conical horn shape. FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A.

In this example, the slope of the conical horn (the coefficient of the highest order term in the following equation ( ₁ )) is the parameter a1. As shown in FIG. 5, when considered on the xy plane, the conical horn is cut off by a straight line represented by Equation ( ₁ ), and the coefficient a1 is a parameter. Here, the directivity is evaluated when the parameter _a1 is changed in the range [0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4].

y=a1x+b ( ₁ )
In other words, the solid formed by rotating the straight line represented by equation (1) by 360° around the _x -axis is _a sphere The base 11 is formed so as to have a shape cut from the . FIG. 6 shows a cross-sectional view of the base 11 in the xy plane at a ₁ =[0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4].

<Example 2 of the shape of the concave portion 111-n>
The shape of the recess 111-n may be a parabolic horn. In other words, the shape of the recess 111-n may be formed such that the rate of change in the diameter of the recess 111-n increases from the open end toward the bottom.

(A) of FIG. 7 is a plan view of an example of a recess 111-n having a parabolic horn shape. FIG. 7B is a cross-sectional view taken along line 7B-7B of FIG. 7A.

In this example, let the coefficient of the highest order term in the following equation ( ₂ ) be the parameter a2. As shown in FIG. 8, when considered on the xy plane, the parabolic horn is cut off by a quadratic curve represented by Equation (2), and the coefficient _a2 is a parameter. Here, directivity is evaluated when _a2 is changed in the range [0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 4.0, 6.0, 8.0].

y= ^a2x2 +b ( ₂ )
In other words, the solid formed by rotating the curve expressed by equation (2) by 360° about the _y -axis is _a sphere The base 11 is formed so as to have a shape cut from the . FIG. 9 shows a cross-sectional view of the base 11 in the xy plane at a ₂ =[0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 4.0, 6.0, 8.0].

<Example 3 of the shape of the concave portion 111-n>
The shape of the recess 111-n may be the shape of an exponential horn. In other words, the shape of the recess 111-n may be formed such that the rate of change in the diameter of the recess 111-n decreases from the open end toward the bottom.

(A) of FIG. 10 is a plan view of an example of a recess 111-n having an exponential horn shape. FIG. 10B is a cross-sectional view taken along line 10B-10B of FIG. 10A.

In this example, the parameter a3 is the coefficient of the highest order term in the exponent part of the following equation ( ₃ ). As shown in FIG. 11, when considered on the xy plane, the exponential horn is cut off by an exponential curve represented by Equation ( ₃ ), and the coefficient a3 is a parameter. Here, the directivity is evaluated when _a3 is changed in the range [0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.8, 1.0, 2.0, 4.0].

y=e ^a_3(xb) (3)
However, the superscript a_3 means _a3 . In other words, the solid formed by rotating the curve expressed by _Equation (3) by 360° about the x-axis is _a sphere The base 11 is formed so as to have a shape cut from the . FIG. 12 represents a cross-sectional view of the base 11 in the xy plane at a ₃ =[0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.8, 1.0, 2.0, 4.0].

<Structure Common to Examples 1 to 3>
The configuration common to Examples 1 to 3 of the shape of the concave portion 111-n will be described below. In this embodiment, the sound collecting portion of the microphone 12-n is placed on a straight line L passing through the center of the base or near the center of the base and the center or approximate center of the outer periphery or bottom of the recess 111-n. .

Also, the sound collecting portion of the microphone 12-n is preferably installed so that the distance between the sound collecting portion of the microphone 12-n and the center of the base is 1/2 or less of the radius of the base.

Of course, the sound collecting portion of the microphone 12-n may be installed such that the distance between the sound collecting portion of the microphone 12-n and the center of the base is larger than 1/2 of the radius of the base.

The smaller the distance between the sound collecting part of the microphone 12-n and the center of the base part, the stronger the directivity of the microphone 12-n and the narrower the directivity width of the microphone 12-n. Therefore, the distance between the sound collecting portion of the microphone 12-n and the center of the base portion is appropriately determined according to the directivity required for the microphone 12-n.

Thus, by changing the distance between the sound collecting portion of the microphone 12-n and the center of the base and the shape of the concave portion 111-n, the directivity of the microphone array 1 can be made to be the desired directivity.

Although the microphone 12-n is installed so as to contact the inner bottom surface of the concave portion 111-n in FIG. 3, it may be installed so as not to contact the inner bottom surface of the concave portion 111-n. In either case, the sound collecting portion of the microphone 12-n is placed on a straight line L passing through the center of the base or the vicinity of the center of the base and the center or approximate center of the outer circumference or bottom of the recess 111-n.

The shape of the rim on the open end side (surface side) of the concave portion 111-n illustrated in this embodiment is substantially circular. However, "substantially circular" means a circular shape or a shape close to a circular shape (substantially circular). An example of a nearly circular shape is an ellipse whose ratio of the long axis to the short axis is equal to or less than a predetermined value γ1, and a polygon with line symmetry or point symmetry. However, γ1 is a real number larger than 1. Examples of γ1 are γ1=1.1, 1.2, 1.3, 1.4, 1.5, and so on. The edge on the open end side (surface side) is larger than the diameter (for example, diameter) of the sound collecting portion of the microphone 12-n. An example of the diameter of the rim on the open end side (surface side) is twice the diameter (for example, the diameter) of the sound collecting portion of the microphone 12-n, or nearly twice the diameter.

Each microphone 12-n (where n=1, . However, the interval (distance) between the sound collecting parts of the microphones 12-n adjacent to each other is substantially the same. That is, the interval between the sound collecting parts of the microphones 12-n adjacent to each other is a predetermined value or its vicinity. The distance between each sound collector and the two adjacent sound collectors is substantially the same. Note that α and β are substantially the same means that α and β are the same, or that α and β are substantially the same. That α and β are almost the same means that the difference δ=|α−β| between α and β is greater than 0% and less than or equal to γ2% with respect to α. Examples of γ2 are γ2=1,3,5,10,20,30,40,50.

<Filter calculation>
Using the acquired impulse responses, a filter for beamforming is calculated with an arbitrary direction in which the sound source s is located at 36 locations as the target direction of the target sound, and the directional characteristics of beamforming are obtained. Filter calculation conditions are shown below.

Calculate the filter coefficients using MVDR (Minimum Variance Distortionless Response). At that time, the target direction ±10° is set as the target sound direction, and the others are set as the noise direction. When the filter is used, the frequency response from each sound source position is aggregated for each 1/3 octave band and evaluated for each center frequency.

<Simulation result>
The directional characteristics are known from the signal (simulation result x) obtained by filtering the signal picked up by the simulated microphone array 1 .

FIG. 13 shows the directional characteristics of a microphone array (without base 11) consisting of only four microphones 12-n. Center frequencies are 500Hz and 1kHz. The directivity characteristics are obtained when the target direction is set to 0°, 20°, 40°, 60°, and 80°, and in FIG. 13, the directivity characteristics are superimposed on the horizontal axis with the target direction set to 0°. The vertical axis indicates the sensitivity for each angle. The sensitivity is corrected so that the sensitivity in the target direction is 0 dB. Note that since there is no base 11, the four microphones 12-n are not fixed to the recesses 111-n, and θ _m =0°, 90°, 180°, 270° of a circle with a radius of r _m =0.1 m. It is placed at the position of °.

14 to 20, the shape of the concave portion 111-n is a conical horn,
y=a1x+b ( ₁ )
A solid formed by rotating the straight line represented by the formula (1) by 360° about the x-axis is cut from an approximate sphere with a radius of r _a at θ _m =0°, 90°, 180°, and 270°. The directional characteristics of a microphone array consisting of a shaped base 11 and four microphones are shown. 14 to 20 correspond to a ₁ =0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, respectively. From FIGS. 14 to 20, it can be seen that the directional characteristics change as the shape of the concave portion 111-n changes.

Even when the shape of the concave portion 111-n is a parabolic horn or an exponential horn, the directional characteristics change as the shape (parameters a ₂ and a ₃ ) of the concave portion 111-n changes.

Next, the evaluation unit 110 of the design device 100 will be explained.

<Evaluation Unit 110 and Storage Unit 120>
The evaluation unit 110 receives the simulation result x described above, evaluates the directivity characteristics for each shape of the concave portion for each frequency, and stores the evaluation result y in the storage unit 120 . For example, the following evaluation methods are conceivable.

(1) Evaluate the sharpness of directivity. To compare the directivity sharpness, we introduce the 'n' dB beamwidth. This considers the directivity of the microphone array to be similar to the 3 dB beamwidth used in the directivity of the antenna. That is, the average of angles that are attenuated by "n" dB is obtained with respect to the target direction of 0°. With respect to the target direction t [°], when the positive direction angle that attenuates “n” dB is α _{n_t} and the negative direction angle is β _{n_t} (value is a negative number), the “n” dB beam width w _{Calculate n} by the following formula.

Note that m is the total number of target directions for which the directivity calculation was performed. In the example of FIG. 3, m=36. It can be evaluated that the smaller the “n” dB beam width w _n is, the sharper the directional characteristics are realized.

In FIG. 21, the shape of recess 111-n indicates the 'n' dB beamwidth of the conical horn. “n” shall be -1,-2,…,-10dB. A black circle indicates the point where the beam width is the smallest, resulting in the sharpest directional performance. It can be seen that a sharper directional characteristic can be formed compared to the case where there is no base. It can be seen that relatively sharp directional characteristics are achieved at a ₁ =0.25 and a ₂ =0.2 for center frequencies of 500 Hz and 1000 Hz, respectively.

FIG. 22 shows the 'n' dB beamwidth of the parabolic horn where the shape of the recess 111-n is. It can be seen that a relatively sharp directional characteristic is achieved at a ₂ =4.0 with a center frequency of 1000 Hz.

In FIG. 23, the shape of recess 111-n indicates the 'n' dB beamwidth of the exponential horn. It can be seen that relatively sharp directional characteristics are achieved at a ₃ =0.15 and a ₃ =0.1 for center frequencies of 500 Hz and 1000 Hz, respectively.

From FIGS. 6, 9, 12 and 21 to 23, it can be seen that the narrower the opening of the recess, the sharper the directional characteristics, but the tendency of performance to drop if the opening of the recess is too narrow.

FIG. 24 shows the optimal parameter 'n' dB beamwidth for each horn. It can be seen that the conical horn with a ₁ =0.25 and the parabolic horn with a ₂ =4.0 achieve the sharpest directional characteristics at center frequencies of 500 Hz and 1000 Hz, respectively.

(2) It is desirable to exhibit similar directional beam shapes in any target direction. Therefore, the variation in the shape of the directivity beam formed in an arbitrary direction is evaluated. To assess the directional beam shape variation, we introduce the 'n' dB beam average bias. With respect to the target direction t [°], let α _{n_t} be the angle in the positive direction that attenuates “n” dB, and let β _{n_t} be the angle in the negative direction (value is a negative number), then “n” dB beam average deflection Calculate θ _n by the following equation.

“n” dB indicates that the smaller the beam average bias θ _n is, the smaller the variation in the directional beam shape formed (the directional beam shapes are equal).

FIG. 25 shows the 'n' dB beam average deflection of the conical horn where the shape of recess 111-n is. “n” shall be -1,-2,…,-10dB. The black circles indicate the average bias in the parameter corresponding to the beamwidth with sharpest directional performance. When the center frequency is 500 Hz and below 8 dB, compared to the case without the base, the 'n' dB beam average deviation is 10° or less, and it can be seen that almost the same directional characteristics can be formed. When the center frequency is 1000 Hz, when a ₁ =0.1, the "n" dB beam average deviation is 10° or less, and almost the same directional characteristics can be formed. This is thought to be because, as in the case of a ₁ =0.1, when the shape difference of the concave portion 111-n is small, the number of times of reflection by the base portion increases and the effect thereof becomes large.

FIG. 26 shows the 'n' dB beam average deflection of a parabolic horn whose shape is recess 111-n. When the center frequency is 500 Hz and below 8 dB, compared to the case without the base, the 'n' dB beam average deviation is 10° or less, and it can be seen that almost the same directional characteristics can be formed. With a center frequency of 1000 Hz, a ₂ =4.0, which forms a sharp directivity, has a small "n" dB beam average bias value, and almost the same directivity can be formed.

FIG. 27 shows that the shape of recess 111-n indicates the 'n' dB beam average deflection of the exponential horn. It can be seen that for small beamwidths, a ₃ =0.1, a ₃ =0.15, the 'n' dB beam average bias is also small.

FIG. 28 shows the 'n' dB beam average bias of the sharp beamwidth parameter (see FIG. 24) for each horn. At 8 dB or less, the 'n' dB beam average deviation is generally 10° or less, and it can be seen that nearly identical directional characteristics can be formed.

The evaluation unit 110 combines information on the shape of the recess (for example, a ₁ , a ₂ , a ₃ ), the center frequency, and the evaluation result y so that the evaluation of the directivity characteristics for each shape of the recess and for each frequency can be known. Stored in the storage unit 120 . The evaluation result y is, for example, a combination of the 'n' dB beamwidth w _n and the beamwidth average bias θ _n . Further, for example, the parameter with the sharpest directivity and the smallest variation in beam shape of directivity may be stored in the storage unit 120 as the evaluation result y.

<Input unit 130>
The input unit 130 receives the input of the property of the acoustic signal that the user wants to collect and the desired directivity (S130), and outputs the input to the design unit 140. FIG. For example, the property of an acoustic signal is the center frequency of the acoustic signal to be collected, and the desired directivity means the sharpness of the desired directivity and the dispersion of the beam shape of the desired directivity. The input unit 130 is an input device such as a keyboard, mouse, and touch panel, and various interfaces that receive input from the input device.

<Design Department 140>
The design unit 140 receives the property of the acoustic signal that the user wants to collect and the desired directivity, refers to the storage unit 120, and selects a recess suitable for the property of the input acoustic signal that the user wants to collect and the desired directivity. The shape is designed (s140), and the designed shape of the recess is output. At this time, the shape of the base 11 having a total of N concave portions 111-n and the position of the microphone 12-n may be output.

If the characteristics of the acoustic signal to be collected and the desired directivity indicate that the center frequency is 500 Hz, the directivity is sharp, and the beam shape variation of the directivity is small, the evaluation of FIGS. 21 to 28 Referring to the result, the shape of the concave portion is assumed to be an exponential horn, and a ₃ =0.15 is output. With such a configuration, it is possible to form a directivity shape with a narrow opening, sharp directivity and little variation.

<Output unit 150>
The output unit 150 outputs the shape of the recess designed by the design unit 140 and the shape of the base 11 including the recess 111-n to a presentation unit such as a display, an external memory, a terminal connected via a network, and the like. . For example, the shape of the base 11 having N concave portions 111-n may be output to a 3D printer or the like, and the base 11 may be formed by the 3D printer or the like.

<effect>
By adopting such a configuration, it is possible to design a microphone array by evaluating the effects of the sharpness of directivity and variations in the shape of the directivity due to the shape of various recesses, without actually fabricating the microphone array. Become. When the directivity desired by the user indicates that the directivity is sharp and the variation in the beam shape of the directivity is small, a microphone array with a small difference in directivity performance for each direction of arrival is designed by the above configuration. can be done.

<Modification>
In the present embodiment, the numbers and installation positions of the microphones 12-n and recesses 111-n are predetermined, but may be set by the user. For example, the configuration may be such that the user inputs, via the input unit 130, the property of the acoustic signal to be collected, the desired directivity, and the number N of the microphones 12-n to be installed. In this case, the installation positions of the recesses 111-n are specified according to the number N of expected inputs, and the installation positions of the microphones are specified according to the shape of the recesses 111-n provided at the installation positions. For example, when N=9, the nine microphones 12-n are θ _m =0°, 40°, 80°, 120°, 160°, 200°, 240°, 280°, 320° of a circle with radius r _m , and nine recesses 111-n are formed so that nine microphones 12-n are arranged on the inner wall surface. Then, the simulation result x is obtained by the same simulation as in the first embodiment, evaluated, and stored in the storage unit 120 .

In this embodiment, the parameters a ₁ , a ₂ , and a ₃ are exemplified as information about the shape of the recess, but the opening of the recess, the inclination inside the recess, the size of the recess, and the like may also be used.

In addition, in the present embodiment, information on the shape of the recess (for example, a ₁ , a ₂ , a ₃ ), the center frequency, and the evaluation result y are combined so that the evaluation of the directivity characteristics for each shape of the recess and for each frequency can be understood. Although the combination is stored in the storage unit 120 , the opening of the recess, the inclination inside the recess, the size of the recess, the number of recesses, etc., and the directional characteristics may be formulated and stored in the storage unit 120 . In this case, the design unit 140 receives the properties and desired directivity of the acoustic signal that the user wants to collect, refers to the storage unit 120, and formulates the properties and desired directivity of the input acoustic signal that the user wants to collect. , and design the shape of the recess (opening of the recess, inclination of the interior of the recess, size of the recess, number of recesses, etc.) suitable for the properties of the acoustic signal and the desired directivity, and design the shape of the recess to output

In the present embodiment, the base portion 11 is substantially spherical, but may be substantially cylindrical and may be provided with recesses on the side surfaces.

Alternatively, a microphone array may be configured by spherically arranging N microphones spaced apart from each other by a predetermined distance. In this case, in order to make the intervals between the sound collecting parts of the microphones 12-n adjacent to each other substantially the same, for example, each of the sound collecting parts of the microphones 12-n is arranged at the vertices of a regular polyhedron having N vertices. Alternatively, one may be arranged in each vicinity of the vertex. It is a sphere that circumscribes all the vertices of the regular n-hedron, and uniformity is ensured by arranging the microphones 12-n at the vertices. There are only regular polyhedra: tetrahedron, hexahedron, octahedron, dodecahedron, and icosahedron. The relationship between the constituent faces of each regular polyhedron, the number of faces, the number of sides, and the number of vertices is shown below.

In this way, N is any one of 4, 6, 8, 12, and 20 when one sound collector is arranged at each vertex of the regular polyhedron or in the vicinity of the vertex. The sound collector arranged at each vertex or its vicinity is arranged, for example, in a direction from the center of the regular polyhedron toward its vertex or its vicinity.

The present invention can be applied to waves such as radio waves and light waves other than sound waves, and can be applied to the design of a sensor array having a plurality of radio wave sensors or light wave sensors instead of a microphone array having a plurality of microphones. be able to. However, it is necessary to design the reflection and absorption conditions of the base according to the waves.

<Other Modifications>
The present invention is not limited to the above embodiments and modifications. For example, the various types of processing described above may not only be executed in chronological order according to the description, but may also be executed in parallel or individually according to the processing capacity of the device that executes the processing or as necessary. In addition, appropriate modifications are possible without departing from the gist of the present invention.

<Program and recording medium>
The various processes described above can be performed by loading a program for executing each step of the above method into the storage unit 2020 of the computer shown in FIG. .

A program that describes this process can be recorded on a computer-readable recording medium. Any computer-readable recording medium may be used, for example, a magnetic recording device, an optical disk, a magneto-optical recording medium, a semiconductor memory, or the like.

In addition, the distribution of this program is carried out, for example, by selling, assigning, lending, etc. portable recording media such as DVDs and CD-ROMs on which the program is recorded. Further, the program may be distributed by storing the program in the storage device of the server computer and transferring the program from the server computer to other computers via the network.

A computer that executes such a program, for example, first stores the program recorded on a portable recording medium or the program transferred from the server computer once in its own storage device. Then, when executing the process, this computer reads the program stored in its own recording medium and executes the process according to the read program. Also, as another execution form of this program, the computer may read the program directly from a portable recording medium and execute processing according to the program, and the program is transferred from the server computer to this computer. Each time, the processing according to the received program may be executed sequentially. In addition, the above-mentioned processing is executed by a so-called ASP (Application Service Provider) type service, which does not transfer the program from the server computer to this computer, and realizes the processing function only by its execution instruction and result acquisition. may be It should be noted that the program in this embodiment includes information used for processing by a computer and conforming to the program (data that is not a direct instruction to the computer but has the property of prescribing the processing of the computer, etc.).

Also, in this embodiment, the device is configured by executing a predetermined program on a computer, but at least a part of these processing contents may be implemented by hardware.

Claims

A design of a microphone array having a base with at least N recesses on the surface, N being an integer of 2 or more, and N microphones installed one by one on the inner bottom surface of each of the recesses. a device,
a storage unit for storing a predetermined property and predetermined directivity of an acoustic signal, and a shape of a recess suitable for the predetermined property and predetermined directivity of the acoustic signal;
an input unit that receives input of properties of an acoustic signal to be collected and desired directivity;
a design unit that refers to the storage unit and designs the shape of the recess suitable for the properties of the input acoustic signal to be collected and the desired directivity;
design equipment.
The design device of claim 1,
The shape of the concave portion suitable for the predetermined acoustic signal properties and predetermined directivity is evaluated based on the sharpness of the directivity and the variation in the beam shape of the directivity.
design equipment.
A design of a microphone array having a base with at least N recesses on the surface, N being an integer of 2 or more, and N microphones installed one by one on the inner bottom surface of each of the recesses. a method,
The storage unit stores a predetermined property and predetermined directivity of the acoustic signal, and the shape of the concave portion suitable for the predetermined property and predetermined directivity of the acoustic signal,
an input step of receiving input of properties of an acoustic signal to be collected and desired directivity;
a design step of referring to the storage unit and designing the shape of the recess suitable for the property of the input acoustic signal to be collected and the desired directivity;
design method.
The design method of claim 3,
The shape of the concave portion suitable for the predetermined acoustic signal properties and predetermined directivity is evaluated based on the sharpness of the directivity and the variation in the beam shape of the directivity.
design method.
A program for causing a computer to function as the design device of claim 1 or claim 2.
N is an integer equal to or greater than 2, and has at least a base provided with N recesses on the surface, and N radio wave sensors or light wave sensors installed one by one on the inner bottom surface side of each of the recesses. A sensor array design apparatus comprising:
a storage unit for storing predetermined radio wave or light wave properties and predetermined directivity, and the shape of a concave portion suitable for the predetermined radio wave or light wave properties and predetermined directivity;
an input unit that receives input of properties of radio waves or light waves to be collected and desired directivity;
a design unit that refers to the storage unit and designs the shape of the recess suitable for the property of the input radio wave or light wave to be collected and the desired directivity,
design equipment.