Acoustic array control device, acoustic array system, and control program

Abstract

To freely set a circular arcuate acoustic radiation distribution or sound collection sensitivity distribution in an acoustic array system using a tangent line method.SOLUTION: The control device 20 includes a generation section 21A for generating an arbitrary circular arc by defining a center coordinate and radius of a circular arc as an arbitrary constant among parameters defining a delay time of a tangent line method when a circular arcuate acoustic radiation distribution or a circular arcuate sound collection sensitivity distribution is set by using the tangent line method with respect to an acoustic array where a plurality of acoustic apparatuses are arranged on a straight line.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an acoustic array control device, an acoustic array system, and a control program. [Background technology]

[0002] It is known that in the delay-and-sum beamformer, a typical conventional speaker array, increasing directivity significantly reduces sound attenuation. Sound attenuation is the property of sound waves attenuating according to distance, and in order to reduce sound leakage, it is necessary to maintain or improve sound attenuation.

[0003] For this reason, a technology using the Tangent Line Method (TLM) (also called the Stationary Phase Method) has been devised as a speaker array that can increase directivity while maintaining or improving distance attenuation (see, for example, Non-Patent Documents 1 to 4). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Zhao, S., Hu, Y., Lu, J., Qui, X., Cheng, J., and Burnett, I., “Delivering sound energy along an arbitrary convex trajectory,” Scientific Reports 4:6628 (2014). [Non-Patent Document 2] Zhao, S., Qiu, X., and Burnett, I., “Acoustic contrast control in an arc-shaped area using a linear loudspeaker array,” J. Acoust. Soc. Am. 137(2), 1036-1039 (2015). [Non-Patent Document 3] Zhao, S., Qiu, X., Lu, J., and Cheng, J., “Robust time domain acoustic contrast control in an arc-shaped area using a linear loudspeaker array,” The 22nd International Congress on Sound and Vibration, Florence, Italy (2015). [Non-Patent Document 4] Kaizuka, T., “Controlling a distance from linear loudspeaker arrays to a listening point by using tangent line method,” JASA Express Letters 1, 072801 (2021). Summary of the Invention [Problem to be solved by the invention]

[0005] When the above tangent method is used, an arc-shaped acoustic beam is generated. This tangent method allows the length of the arc to be controlled, so the distance the sound reaches (distance attenuation) can be controlled. Theoretically, it is believed that any arc-shaped or curved acoustic beam can be generated by using the tangent method, but only a few shapes have been reported for which an analytical solution for the tangent method has been reported. When the tangent method is applied to an acoustic array such as a speaker array or a microphone array, for example, in the above non-patent document 4, an analytical solution is derived with the constraint that the Y coordinate of the center of the arc is fixed to the radius R. For this reason, it is difficult to freely set the acoustic radiation distribution, which is the spatial distribution of the arc-shaped acoustic radiation in the speaker array, and the sound collection sensitivity distribution, which is the spatial distribution of the arc-shaped sound collection sensitivity in the microphone array, without any constraints.

[0006] Taking into consideration the above-mentioned facts, the present invention aims to provide an acoustic array control device, an acoustic array system, and a control program that can more freely set an arc-shaped acoustic radiation distribution or sound collection sensitivity distribution in an acoustic array system using the tangent method. [Means for solving the problem]

[0007] The acoustic array control device according to the first aspect includes a generation unit that, when setting an arc-shaped acoustic radiation distribution or an arc-shaped sound collection sensitivity distribution using the tangent method for an acoustic array in which a number of acoustic devices are arranged in a straight line, generates an arbitrary arc by setting the center coordinates and radius of the arc-shaped arc as arbitrary constants among parameters that define the delay time of the tangent method.

[0008] The acoustic array control device according to the second aspect is the acoustic array control device according to the first aspect, wherein the generation unit determines the center coordinates and radius of the arc so that an index value representing an acoustic contrast related to the acoustic array is equal to or greater than a certain value.

[0009] The acoustic array control device of the third aspect is the acoustic array control device of the second aspect, in which the index value is expressed as a ratio between a sound pressure level in a first area defined as an area where a sound beam reaches, and a sound pressure level in a second area defined as at least a part of an area other than the first area.

[0010] An acoustic array control device according to a fourth aspect is the acoustic array control device according to the third aspect, wherein the generation section determines a center coordinate and a radius of the arc so as to maximize the ratio.

[0011] An acoustic array control device according to a fifth aspect is the acoustic array control device according to the third aspect, wherein the generation section determines a center coordinate and a radius of the arc so that an average value of the frequency of the ratio is maximized.

[0012] The acoustic array control device of a sixth aspect is an acoustic array control device of any one of the first to fifth aspects, further comprising a delay setting unit that sets a delay time of a drive signal or a sound pressure signal for the acoustic array based on the arc generated by the generation unit so that the acoustic radiation distribution or the sound collection sensitivity distribution becomes arc-shaped.

[0013] An acoustic array control device according to a seventh aspect is an acoustic array control device according to any one of the first to sixth aspects, in which the acoustic equipment is a speaker and the acoustic array is a speaker array in which a plurality of the speakers are arranged on the straight line.

[0014] An acoustic array control device according to an eighth aspect is an acoustic array control device according to any one of the first to sixth aspects, in which the acoustic equipment is a microphone, and the acoustic array is a microphone array in which a plurality of the microphones are arranged on the straight line.

[0015] An acoustic array system according to a ninth aspect comprises an acoustic array control device according to any one of the first to eighth aspects, and an acoustic array in which a plurality of acoustic devices are arranged in a straight line, the acoustic radiation distribution or the sound collection sensitivity distribution being set in an arc shape according to control by the acoustic array control device.

[0016] A control program according to a tenth aspect causes a computer to execute the following: when setting an arc-shaped acoustic radiation distribution or an arc-shaped sound collection sensitivity distribution using the tangent method for an acoustic array in which a number of acoustic devices are arranged in a straight line, the program causes a computer to generate an arbitrary arc by setting the center coordinates and radius of the arc-shaped arc as arbitrary constants, among parameters that define the delay time of the tangent method. Effect of the Invention

[0017] As described above, according to the present invention, in an acoustic array system using the tangent method, it is possible to more freely set an arc-shaped acoustic radiation distribution or sound collection sensitivity distribution. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing an example of a configuration of a speaker system according to an embodiment; [Diagram 2] FIG. 2 is a block diagram showing an example of an electrical configuration of a control device according to the embodiment. [Diagram 3] FIG. 2 is a block diagram showing an example of a functional configuration of a control device according to the embodiment. [Figure 4] 5A and 5B are diagrams illustrating an arbitrary circular arc generation process using the tangent method according to an embodiment. [Diagram 5] 11A to 11C are diagrams illustrating a circular arc optimization process according to the embodiment. [Figure 6] 1 is a flowchart showing an example of a process flow of an iterative optimization algorithm according to an embodiment. [Figure 7] FIG. 13 is a diagram showing a simulation result of a monopole according to a comparative example. [Figure 8] FIG. 13 is a diagram showing a simulation result of a DAS method according to a comparative example. [Figure 9] FIG. 13 is a diagram showing a simulation result of an ACC method according to a comparative example. [Figure 10] FIG. 13 is a diagram showing a simulation result of a non-optimum tangent method according to a comparative example. [Figure 11] FIG. 13 is a diagram showing a simulation result of the optimal tangent method according to the embodiment. [Figure 12] FIG. 13 is a diagram showing a simulation result of another optimal tangent method according to an embodiment. [Figure 13] 1 is a schematic diagram illustrating an example of a configuration of a microphone system according to an embodiment. [Figure 14] FIG. 13 is a diagram showing a simulation result when the optimal tangent method according to the embodiment is applied to a microphone array. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an example of a mode for implementing the technology of the present disclosure will be described in detail with reference to the drawings. Note that components and processes that perform the same operation, action, and function may be given the same reference numerals throughout all the drawings, and duplicated explanations may be omitted as appropriate. Each drawing is merely shown in a schematic manner to allow a sufficient understanding of the technology of the present disclosure. Therefore, the technology of the present disclosure is not limited to only the illustrated examples. In addition, in this embodiment, explanations of configurations that are not directly related to the present disclosure or well-known configurations may be omitted.

[0020] 1 is a schematic diagram showing an example of the configuration of a speaker system 10 according to this embodiment. The speaker system 10 according to this embodiment generates a sound beam using the tangent method.

[0021] 1, a speaker system 10 according to this embodiment includes a speaker array 12 and a control device 20. The speaker array 12 is a linear array, and is configured by arranging a plurality of speakers 16 at predetermined intervals on a straight line. The size of the speaker array 12, and the number and intervals of the speakers 16 are changed depending on the position of a listening area, which will be described later, and the frequency band of the sound to be output.

[0022] The speaker 16 is an example of an acoustic device, the speaker array 12 is an example of an acoustic array, the speaker system 10 is an example of an acoustic array system, and the control device 20 is an example of an acoustic array control device.

[0023] In this embodiment, as an example, the frequency band of the sound is set to 300 Hz or more and 3400 Hz or less. The interval between the speakers 16, which are point sound sources, is set to 0.05 m, and the length of the speaker array 12 is set to 1.0 m. The number of speakers 16 is 21. In other words, the interval between adjacent speakers 16 is set to a value equal to or less than half the wavelength of a 3400 Hz sound wave.

[0024] The speaker array 12 is electrically connected to a control device 20. The control device 20 controls the driving of each of the multiple speakers 16 that constitute the speaker array 12.

[0025] FIG. 2 is a block diagram showing an example of the electrical configuration of the control device 20 according to the present embodiment.

[0026] As shown in FIG. 2, the control device 20 according to this embodiment includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, an input / output unit (I / O) 24, a memory unit 25, and a connection unit 26.

[0027] The CPU 21, the ROM 22, the RAM 23, and the I / O 24 are connected to each other via a bus. The I / O 24 is connected to various functional units including a storage unit 25 and a connection unit 26. These functional units are capable of communicating with the CPU 21 via the I / O 24.

[0028] For example, a hard disk drive (HDD), a solid state drive (SSD), a flash memory, or the like is used as the storage unit 25. A control program 25A according to the present embodiment is stored in the storage unit 25. The control program 25A may be stored in the ROM 22.

[0029] The control program 25A may be pre-installed in the control device 20, for example. The control program 25A may be realized by storing it in a non-volatile storage medium or distributing it via a network and appropriately installing it in the control device 20. Note that examples of non-volatile storage media include a CD-ROM (Compact Disc Read Only Memory), a magneto-optical disk, a HDD, a DVD-ROM (Digital Versatile Disc Read Only Memory), a flash memory, a memory card, and the like.

[0030] The connection unit 26 is an interface for connecting to the speaker array 12 .

[0031] The CPU 21 of the control device 20 according to this embodiment writes a control program 25A stored in the ROM 22 or the storage unit 25 into the RAM 23 and executes the program, thereby functioning as each unit shown in FIG.

[0032] FIG. 3 is a block diagram showing an example of a functional configuration of the control device 20 according to the present embodiment.

[0033] As shown in FIG. 3, the CPU 21 of the control device 20 according to this embodiment functions as a generating unit 21A and a delay setting unit 21B.

[0034] When setting an arc-shaped acoustic radiation distribution for the speaker array 12 using the tangent method, the generator 21A generates an arbitrary arc by setting the center coordinate and radius of the arc, which is the shape of the sound beam, as arbitrary constants among parameters that define the delay time of the tangent method. The acoustic radiation distribution is the spatial distribution of acoustic radiation when an arc-shaped sound beam is generated. Specifically, the generator 21A determines the center coordinate and radius of the arc so that the index value representing the acoustic contrast for the speaker array 12 is equal to or greater than a certain value. The "certain value" here is set to an appropriate value, for example, based on past knowledge or experiments.

[0035] The index value representing the acoustic contrast is expressed, for example, as the ratio of the sound pressure level in the listening area to the sound pressure level in the non-listening area (hereinafter referred to as the "sound pressure ratio"). The listening area is an example of a first area, and is defined as an area where a sound beam reaches. The non-listening area is an example of a second area, and is defined as at least a part of an area other than the listening area. Specifically, the non-listening area is defined as an area whose distance from a sound source (here, the speaker 16) is farther than the listening area, for example, a far field representing a sphere of infinite radius. The non-listening area is also defined as an area whose distance from a sound source (here, the speaker 16) is the same as the listening area or is closer than the listening area and whose direction is different from that of the listening area. In this case, it is desirable for the generating unit 21A to determine the center coordinates and radius of the arc so that the sound pressure ratio is maximized.

[0036] The delay setting unit 21B sets a delay time of the drive signal for the speaker array 12 based on the arc generated by the generation unit 21A so that the sound radiation distribution becomes arc-shaped.

[0037] Next, with reference to Figs. 4(A) and 4(B), a process for generating an arbitrary circular arc by the generating unit 21A (hereinafter referred to as "arbitrary circular arc generating process") will be specifically described.

[0038] 4(A) and 4(B) are diagrams for explaining the arbitrary arc generation process using the tangent method according to this embodiment. Note that, in this example, the speaker array 12 (see FIG. 1), which is the sound source, is arranged along the x-axis, and the explanation is given assuming an acoustically free space.

[0039] As shown in Figures 4(A) and 4(B), the curved trajectory of a sound beam generated by the tangent method is regarded as a circular arc C with a center at arbitrary coordinates (a, b) and an arbitrary radius R. Consider a tangent line L at a point on the circular arc C. Let the point of contact between the tangent line L and the circular arc C be (x c ,y c ), the angle between the tangent line L and the y-axis is θ, and the intersection point between the tangent line L and the x-axis is x. In this case, the circular arc C is expressed by the following formula (1).

[0040] JPEG2025021018000002.jpg1184(1)

[0041] However, x c is derived from the arc C using the following formula (2).

[0042] JPEG2025021018000003.jpg1281(2)

[0043] The arc C is treated as the envelope of the tangent line L. x c > a, as shown in Figure 4(A), is defined as -π / 2 < θ < π / 2. On the other hand, x c < a, as shown in Figure 4(B), is defined as -π / 2 < θ < π / 2. The relationship between the intersection point x and the angle θ in the right - half circle and the left - half circle is represented by the following formula (3).

[0044] JPEG2025021018000004.jpg1055(3)

[0045] Substituting the above formula (2) into the above formula (3) gives formula (4).

[0046] JPEG2025021018000005.jpg12118(4)

[0047] Furthermore, tanθ is represented by the following formula (5).

[0048] JPEG2025021018000006.jpg1348(5)

[0049] Substituting the above formula (2) into the above formula (5) gives formula (6).

[0050] JPEG2025021018000007.jpg1461(6)

[0051] By dividing the above equation (4) by the above equation (6), y c A quadratic equation for is derived.

[0052] JPEG2025021018000008.jpg18129(7)

[0053] On the other hand, sin θ is expressed by the following equation (8).

[0054] JPEG2025021018000009.jpg1650(8)

[0055] By substituting the above formula (6) into the above formula (8), formula (9) is derived.

[0056] JPEG2025021018000010.jpg1540(9)

[0057] By substituting the above formula (7) into the above formula (9), formula (10) is derived.

[0058] JPEG2025021018000011.jpg1799(10)

[0059] The time dependence is assumed to be periodic and of the form e-jωt, where ω is the angular frequency. The phase relationship depicted in FIG. 4 can be written as follows:

[0060] JPEG2025021018000012.jpg12104(11)

[0061] The following equation (12) is derived from the above equation (11).

[0062] JPEG2025021018000013.jpg1265(12)

[0063] where φ(x) is the phase of the point source at (x,0), dφ(x) and dx are the phase shift and the distance between two adjacent point sources, respectively, and k is the wave number. Equation (12) can be regarded as the phase shift of the DAS (Delay And Sum) method to generate the tangent line L to θ. Substituting equation (10) into equation (12) and integrating along the x-axis, the following equation (13) is derived.

[0064] JPEG2025021018000014.jpg11164(13)

[0065] The positive or negative sign is determined according to the position of arc C (right or left semicircle). That is, the sign outside the brackets in equation (13) is linked to equation (12), and the sign inside the brackets in equation (13) is linked to equation (7). The above equation (13) represents a spatial phase profile for generating arc C as an envelope of tangent L. For an array of N point sound sources, the continuous function can be discretized as shown in the following equation (14).

[0066] JPEG2025021018000015.jpg12164(14)

[0067] where x n represents the position of the nth point sound source. The delay time of each point sound source is expressed by the following equation (15).

[0068] JPEG2025021018000016.jpg11164(15)

[0069] Here, c0 represents the speed of sound. The delay time τ(x n ) does not depend on the frequency, the arbitrary circular arc generation process according to this embodiment can be realized by delay time control. In other words, by using the above formula (15), the delay time τ(x n Among the parameters that define the sound beam, the center coordinates (a, b) and radius R of the arc C, which is the shape of the sound beam, are set as arbitrary constants to generate an arbitrary arc C.

[0070] Next, the optimization process for the arc C (hereinafter referred to as the "arc optimization process") will be specifically described with reference to FIG.

[0071] Fig. 5 is a diagram for explaining the arc optimization process according to this embodiment, and shows a schematic diagram of a speaker array 12 applied to a personal audio system.

[0072] As described above, the multiple speakers 16 (herein referred to as "point sound sources") that make up the speaker array 12 are arranged along the x-axis. For ease of explanation, the distance between two adjacent point sound sources is denoted by d, and the position of the point sound sources and the length of the arrangement (array length) are denoted by x. n =(n-1)d and L = (N-1)d, where n = 1, 2, . . . , N, and the listening point Lp(x0, y0) included in the listening area is located at any position on a semicircle with center (L / 2, 0) and radius R0.

[0073] The directivity angle is represented by θ0, and 0°≦θ0≦180°. Therefore, the listening point Lp(x0,y0) can be written as (L / 2+R0cosθ0,R0sinθ0). The arc-shaped acoustic beam is generated by the tangent method with the aim of delivering sound toward the listening point Lp(x0,y0) while attenuating the sound beyond the listening point Lp(x0,y0) as much as possible. The generated arc C is determined by substituting the listening point Lp(x0,y0) into the above formula (1). However, the arc C is not determined unless the center coordinates (a,b) of the arc C are assigned. When the center coordinates (a,b) are assigned, the radius R is determined. Therefore, in this embodiment, the optimal center coordinates (a,b) and radius R are determined based on the acoustic contrast between the listening point Lp(x0,y0) and other places (for example, the far field). An index value AC representing the acoustic contrast is defined, for example, as the ratio of the square of the sound pressure at the listening point Lp(x0, y0) to the active acoustic power, as shown in the following equation (16).

[0074] JPEG2025021018000017.jpg2271(16)

[0075] Here, q is a column vector of the complex volume velocity of each point sound source, z is a row vector of the radiation impedance from each point sound source to the listening point Lp(x0,y0), R is a square matrix of the radiation resistance between the point sound source positions, H (superscript) represents the conjugate transpose. zq is the complex sound pressure at the listening point Lp(x0,y0), q H z H zq represents the squared sound pressure. q H Rq is the active acoustic power, which is proportional to the sum of the squares of the amplitudes of the sound pressure on a sphere of infinite radius, i.e., in the far field. Therefore, the index value AC represents the acoustic contrast between the listening area including the listening point Lp(x0,y0) and the non-listening area, which is the far field. Therefore, the index value AC can also be expressed as the following equation (17).

[0076] JPEG2025021018000018.jpg2277(17)

[0077] However, SP listening is the spatial average of the squared amplitude of the sound pressure in the listening area including the listening point Lp(x0,y0). SP non-listening is the spatial average of the squared amplitude of sound pressure in the non-listening area, which is the far field. The sum of the squared amplitude of sound pressure in the far field is proportional to the sound power, so SP non-listening may be used as the acoustic power. In other words, the index value AC represents the ratio (sound pressure ratio) of the sound pressure level in the listening area to the sound pressure level in the non-listening area.

[0078] Here, the center coordinates (a, b) for maximizing the index value AC are determined using the iterative optimization algorithm executed by the above-mentioned control program 25A.

[0079] FIG. 6 is a flowchart showing an example of the process flow of the iterative optimization algorithm according to this embodiment.

[0080] 6, the CPU 21 sets amin, amax, bmin, and bmax as a calculation range. That is, the iterative calculation is performed within the calculation range defined by (amin≦a≦amax, bmin≦b≦bmax).

[0081] In step S102, the CPU 21 determines the center coordinates (a, b) and radius R of the arc C that satisfy the above-mentioned formula (1) for the given listening point Lp(x0, y0), as an example. That is, a and b are sequentially substituted into formula (15) within the ranges of amin≦a≦amax, bmin≦b≦bmax, and R is determined accordingly.

[0082] In step S103, the CPU 21 calculates the delay time τ (x n ) is derived.

[0083] In step S104, the CPU 21 calculates the delay time τ(x n If it is determined that it has been derived (if the determination is positive), the process proceeds to step S105, and if it is determined that it has not been derived (if the determination is negative), the process returns to step S102 and the process is repeated.

[0084] In step S105, the CPU 21 calculates the index value AC for all cases of the center coordinates (a, b) and radius R derived in step S102 according to the above-mentioned formula (16) or formula (17).

[0085] In step S106, the CPU 21 compares the index value AC calculated in step S105 for all cases of center coordinates (a, b) and radius R, determines the center coordinates (a, b) and radius R that maximize the index value AC, and terminates this iterative optimization algorithm.

[0086] In the above iterative optimization algorithm, the frequency average value AC, which is the average value of the frequencies of the index values ​​AC, is calculated using the following formula (18). ave Calculate the average frequency ACave The center coordinates (a, b) and the radius R may be determined so that the following equation is maximized:

[0087] JPEG2025021018000019.jpg1677(18)

[0088] where f m represents the mth frequency. The average frequency AC ave is obtained by averaging index values ​​AC obtained at 10 Hz intervals in the range of 300 Hz to 3400 Hz inclusive in the audio frequency band, for example.

[0089] Next, with reference to Figures 7 to 12, we will explain the simulation results of the tangent method with arc optimization processing according to this embodiment (hereinafter referred to as the "optimal tangent method"), and the simulation results of a monopole (one point sound source), a DAS (Deray And Sum) beamformer method, an ACC (Acoustic Contrast Control) method, and a tangent method without arc optimization processing (hereinafter referred to as the "non-optimal tangent method") according to comparative examples.

[0090] In the system configuration shown in Figure 5 above, the spacing between point sound sources d = 0.05 m, the number of point sound sources N = 21, the array length L = (N-1)d = 1 m, and the distance from the array center to the listening point Lp (x0, y0) R0 = L = 1 m were set, and a simulation of the sound pressure distribution was performed for each method. Since the spacing between point sound sources d = 0.05 m is almost equal to a half wavelength at 3400 Hz, spatial aliasing can be avoided up to this frequency. 3400 Hz is the upper limit of the audio frequency band. As an example, the listening point Lp corresponding to the directivity angle θ0 = 30°, 60°, and 90° is considered.

[0091] FIG. 7 is a diagram showing a simulation result of a monopole according to a comparative example.

[0092] In the case of the monopole shown in Figure 7, since it is a spherical wave, there is no directivity, and the amplitude of the sound pressure is inversely proportional to the distance, resulting in normal distance attenuation. Figure 7 shows a contour map of the sound pressure level normalized based on the listening point Lp indicated by the star. The interval between the contour lines is 10 dB.

[0093] 8 is a diagram showing a simulation result of the DAS method according to the comparative example. The simulation was performed with the number of point sound sources N=21.

[0094] In the case of the DAS method shown in Figure 8, it is clear that while the directivity can be increased, the distance attenuation deteriorates. Due to the principle of the DAS method generating plane waves, the deterioration of distance attenuation is unavoidable.

[0095] 9 is a diagram showing a simulation result of the ACC method according to the comparative example. The simulation was performed with the number of point sound sources N=21.

[0096] It can be seen that the ACC method shown in Fig. 9 can maintain (or increase) the distance attenuation while increasing the directivity. The ACC method maximizes the index value AC, as in the optimal tangent method according to this embodiment, and therefore can obtain the best possible results. On the other hand, the signal processing is complicated and it is not easy to implement.

[0097] 10 is a diagram showing a simulation result of the non-optimum tangent method according to the comparative example, in which the number of point sound sources is N=21.

[0098] In the case of the non-optimal tangent method shown in Figure 10, a circular arc is generated that passes through the listening point (x0, y0) and has a center coordinate of (0, R). It can be seen that the non-optimal tangent method shows higher directivity than a point sound source, while the distance attenuation is not as degraded as the DAS method. However, it can be seen that both the directivity and the distance attenuation are degraded compared to the ACC method.

[0099] 11 is a diagram showing a simulation result of the optimal tangent method according to the present embodiment. The simulation was performed with the number of point sound sources N=21.

[0100] In the case of the optimal tangent method shown in Figure 11, optimization was performed within the calculation range defined by (amin≦a≦amax, bmin≦b≦bmax) as described above. For example, amin=(L / 2-2.5)m, amax=(L / 2+2.5)m, bmin=-1m, bmax=2m. Both a and b were set at intervals of 0.05m. From this result, it can be seen that the optimal tangent method is able to maintain (or increase) distance attenuation while increasing directivity. For both directivity and distance attenuation, results equivalent to those of the ACC method shown in Figure 9 above were obtained. However, since this is optimization for a single frequency, the optimal arc differs depending on the frequency. For this reason, the delay time τ(x n ) is being changed.

[0101] 12 is a diagram showing a simulation result of another optimal tangent method according to the present embodiment. The simulation was performed with the number of point sound sources N=21.

[0102] In the case of the optimal tangent method shown in FIG. 12, for example, calculations are performed in the range of 300 Hz to 3400 Hz in the voice frequency band at 10 Hz intervals, and the frequency average value AC of the obtained index value AC is ave Calculate the average frequency AC ave The circular arc with the maximum delay time τ(x n In other words, it is possible to achieve the same directivity and distance attenuation as the ACC method shown in Figure 9 above with simple delay control.

[0103] In the system configuration shown in Figure 5 above, the distance between point sound sources d = 0.05 m, the number of point sound sources N = 16, the array length L = (N-1)d = 0.75 m, the distance from the array center to the listening point Lp (x0, y0) R0 = L = 0.75 m, and the distance from the array center to the measurement point = 1.5 m were set, and an experiment was conducted to measure the sound pressure at the set measurement points. The experimental results confirmed that it was possible to achieve directivity and distance attenuation equivalent to the simulation results. As mentioned above, the arc was calculated at 10 Hz intervals in the range from 300 Hz to 3400 Hz in the audio frequency band, and the frequency average value AC of the obtained index value AC was calculated. ave Calculate the average frequency AC ave is the circular arc where is maximum.

[0104] As described above, according to this embodiment, it is possible to set a listening area at any position while suppressing sound leakage to the surroundings.

[0105] In addition, since it is possible to increase the directivity while maintaining (or increasing) the distance attenuation, the sound can be delivered only to users who are close to the sound source.

[0106] In the above embodiment, the sound source is described as one speaker array, but the sound source may be multiple speaker arrays. In this case, an optimal arc may be generated for each of the multiple speaker arrays using the optimal tangent method according to the present embodiment.

[0107] In the above embodiment, a speaker is described as an example of an audio device, but the audio device is not limited to a speaker. By utilizing the reciprocity of sound (reciprocity theorem), it is also possible to realize a microphone array that can pick up only sounds arriving from nearby sound sources.

[0108] 13 is a schematic diagram showing an example of the configuration of a microphone system 30 according to this embodiment. The microphone system 30 according to this embodiment collects sound from a nearby sound source using the tangent method.

[0109] As shown in Fig. 13, a microphone system 30 according to this embodiment includes a microphone array 32 and a control device 20. The microphone array 32 is a linear array, and is configured by arranging a plurality of microphones 36 at predetermined intervals on a straight line. Note that in the microphone array 32, the "listening point" in the speaker array 12 is replaced with the "sound collection point", the "listening area" is replaced with the "sound collection area", and the "non-listening area" is replaced with the "non-sound collection area". The size of the microphone array 32, the number of microphones 36, and the intervals therebetween are changed according to the position of the sound collection area and the frequency band of the sound to be collected.

[0110] The microphone 36 is an example of an acoustic device, the microphone array 32 is an example of an acoustic array, the microphone system 30 is an example of an acoustic array system, and the control device 20 is an example of an acoustic array control device.

[0111] Instead of the speaker 16 shown in FIG. 1, a microphone 36 is arranged as a sound pressure collection point, and the sound pressure at each sound collection point is calculated based on the delay time τ(x n ) and calculate the sum.

[0112] In this case, when setting the sound collection sensitivity distribution in an arc shape using the tangent method for the microphone array 32, the generation unit 21A (see FIG. 3) included in the control device 20 calculates the delay time τ(x n Among the parameters that define the circular arc C, the center coordinates (a, b) and the radius R are set as arbitrary constants to generate an arbitrary circular arc C. The sound pickup sensitivity distribution is the spatial distribution of sound pickup sensitivity.

[0113] The delay setting unit 21B (see FIG. 3) sets a delay time of the sound pressure signal for the microphone array 32 based on the arc generated by the generation unit 21A so that the sound collection sensitivity distribution becomes arc-shaped.

[0114] FIG. 14 is a diagram showing a simulation result when the optimal tangent method according to the present embodiment is applied to the microphone array 32. In FIG.

[0115] The simulation result shown in Fig. 14 shows the sound collection sensitivity level of the microphone array 32 as a contour map. This sound collection sensitivity level is normalized based on the sound collection point Mp. The interval between the contour lines is set to 10 dB. The simulation result shown in Fig. 14 shows the case of "60°, 3400 Hz", and it can be seen that it is similar to the simulation result of "60°, 3400 Hz" shown in Fig. 11 or Fig. 12 described above.

[0116] As described above, according to this embodiment, even when the optimal tangent method is applied to a microphone array, the sound collection area can be set at any position.

[0117] The above-described embodiments may be in the form of a program for causing a computer to execute the functions of each unit of the control device. The embodiments may be in the form of a non-transitory storage medium that stores the program and is readable by a computer.

[0118] Furthermore, the configuration of the control device described in the above embodiment is merely an example, and may be modified according to circumstances without departing from the spirit of the invention.

[0119] Furthermore, the processing flow of the program described in the above embodiment is also one example, and unnecessary steps may be deleted, new steps may be added, or the processing order may be rearranged, without departing from the spirit of the invention.

[0120] In the above embodiment, the processing according to the embodiment is realized by a software configuration using a computer by executing a program, but the present invention is not limited to this. The embodiment may be realized by, for example, a hardware configuration or a combination of a hardware configuration and a software configuration. [Explanation of symbols]

[0121] 10. Speaker System 12 Speaker Array 16 Speakers 20 Control device 21 CPU 21A Generation part 21B Delay setting section 22 ROM 23 RAM 24 I / O 25 Memory section 25A Control Program 26 Connection 30 Microphone System 32 Microphone Array 36 Microphone

Claims

1. A generator for generating an arbitrary arc by using a tangent method to set an arc-shaped acoustic radiation distribution or an arc-shaped sound collection sensitivity distribution for an acoustic array in which a plurality of acoustic devices are arranged on a straight line, the generator generating an arbitrary arc by setting the center coordinate and the radius of the arc as arbitrary constants among parameters defining a delay time of the tangent method; An acoustic array control device comprising:

2. The generation unit determines a center coordinate and a radius of the arc so that an index value representing an acoustic contrast related to the acoustic array is equal to or greater than a certain value.

2. The acoustic array control device of claim 1.

3. The index value is expressed as a ratio between a sound pressure level in a first region defined as a region where a sound beam reaches and a sound pressure level in a second region defined as at least a part of a region other than the first region.

3. The acoustic array control device of claim 2.

4. The generating unit determines a center coordinate and a radius of the arc so as to maximize the ratio.

4. The acoustic array control device of claim 3.

5. The generating unit determines a center coordinate and a radius of the arc so that an average value of the frequency of the ratio is maximized.

4. The acoustic array control device of claim 3.

6. Further comprising a delay setting unit that sets a delay time of a drive signal or a sound pressure signal for the acoustic array based on the arc generated by the generating unit so that the acoustic radiation distribution or the sound collection sensitivity distribution becomes arc-shaped.

2. The acoustic array control device of claim 1.

7. The acoustic device is a speaker, The acoustic array is a speaker array in which a plurality of the speakers are arranged on the straight line.

2. The acoustic array control device of claim 1.

8. the acoustic device is a microphone, The acoustic array is a microphone array in which a plurality of the microphones are arranged on the straight line.

2. The acoustic array control device of claim 1.

9. An acoustic array control device according to any one of claims 1 to 8; An acoustic array in which a plurality of acoustic devices are arranged on a straight line, the acoustic array having the acoustic radiation distribution or the sound collection sensitivity distribution set in an arc shape according to control by the acoustic array control device; An acoustic array system comprising:

10. When setting an arc-shaped acoustic radiation distribution or an arc-shaped sound collection sensitivity distribution using a tangent method for an acoustic array in which a plurality of acoustic devices are arranged on a straight line, an arbitrary arc is generated by setting the center coordinate and radius of the arc as arbitrary constants among parameters that define the delay time of the tangent method, A control program for execution by a computer.

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