Area playback system and playback control device, method and program thereof

Abstract

In one aspect of the present invention, a reproduction control device acquires area specifying information specifying a desired area, defines an optimization problem for reproducing a sound in the desired area, on the basis of the acquired area specifying information, and weight information which is given to a plurality of control points defined in the area, solves the defined optimization problem by a proximal splitting algorithm, and thereby calculates, for each speaker, a filter coefficient for controlling acoustic directional characteristics of a speaker array. Then, in the reproduction control device, by reflecting the calculated filter coefficient in an acoustic signal to be input, an acoustic drive signal for driving the speaker array is generated.

Description

[Technical field]

[0001] One aspect of the present invention relates to an area reproduction system that reproduces sound only in a desired area using a speaker array, and a reproduction control device, method, and program used in this system. [Background technology]

[0002] In recent years, area reproduction technology has been proposed for reproducing sound only in a desired area in public spaces such as train stations, art galleries, and museums. In addition to public spaces, area reproduction in small spaces such as reproducing sound only to people watching television at home, or reproducing navigation sound only to the driver in a car and music to other passengers is also being considered.

[0003] One area reproduction technology being considered is a technology that uses ultrasonic speakers with sharp directionality to reproduce an area. However, ultrasonic speakers generally demodulate ultrasonic waves into audible sounds, which can lead to distortion during demodulation, making the sound quality prone to degradation, and making it particularly difficult to reproduce high-pitched sounds. This problem makes the technology unsuitable for the need to reproduce a variety of content, such as music, in high quality.

[0004] Therefore, area reproduction technology has been proposed that uses a speaker array in which multiple speakers are arranged in a row to reproduce sound only in a desired area and prevent sound from leaking out to other areas (see, for example, Patent Document 1).

[0005] Area reproduction techniques that are being considered include methods that use directivity control technology and acoustic contrast maximization technology. Directivity control technology places control points around a speaker array that has multiple speakers lined up, and designs a filter that controls the amplitude and phase of each speaker based on the sound transmission characteristics from the speaker to the control point. Then, by reflecting the filter coefficient in the input sound signal, the direction in which the sound propagates strongly from the speaker or the direction in which the sound does not propagate is controlled. In contrast, acoustic contrast maximization technology reproduces sound in the desired area by maximizing the sound pressure ratio between the Bright-zone BZ and Dark-zone DZ that are arbitrarily set by the speaker array.

[0006] However, when a filter is designed using the above-mentioned directivity control technology and acoustic contrast maximization technology, the low-frequency filter gain becomes large, exceeding the allowable vibration of the speaker, which may cause sound distortion and make it difficult to reproduce the sound. In addition, significant sound leakage in directions other than the intended direction, that is, the occurrence of acoustic side lobes, is unavoidable.

[0007] To address these problems, a method has been proposed for suppressing the filter gain by using a penalty term to suppress the filter gain (see, for example, Non-Patent Document 1). Also, a method for suppressing sound leakage by using a weighted least squares method has been proposed (see, for example, Non-Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2013-110495 [Non-patent literature]

[0009] [Non-Patent Document 1] MM. Boone, WH. Cho, and JG Ih. "Design of a highly directional endfire loudspeaker array." Journal of the Audio Engineering Society 57.5 (2009): 309-325. [Non-Patent Document 2] Y. Haneda, K. Furuya, and A. Kataoka. "Evaluating small end-fire loudspeaker array under various reverberations." Acoustical science and technology 32.6 (2011): 244-250. Summary of the Invention [Problem to be solved by the invention]

[0010] However, the method of suppressing the filter gain using a penalty term can suppress the filter gain but cannot suppress the occurrence of side lobes. On the other hand, the directivity control technology using the weighted least squares method can be expected to reduce sound leakage but cannot suppress the occurrence of side lobes. In addition, applying weights increases the filter gain, which inevitably leads to sound distortion.

[0011] The present invention has been made in light of the above-mentioned circumstances, and has an object to provide a technology for suppressing the amplitude of a signal supplied to a speaker while suppressing the generation of acoustic side lobes in directions other than the intended direction. [Means for solving the problem]

[0012] In order to achieve the above-mentioned objective, one aspect of the present invention relates to an area playback system that includes a speaker array consisting of an arrangement of multiple speakers and a playback control device connected to the speaker array, and that plays sound in a desired area by individually driving the multiple speakers with an acoustic drive signal whose phase and amplitude are controlled by the playback control device.

[0013] The playback control device acquires area designation information that designates the desired area, defines an optimization problem for playing back sound for the desired area based on the acquired area designation information and weight information to be assigned to a plurality of control points defined in the area, and calculates filter coefficients for controlling the acoustic directional characteristics of the speaker array for each of the plurality of speakers by solving the defined optimization problem using a proximity separation algorithm. The playback control device generates the acoustic drive signal by reflecting the calculated filter coefficients in an input acoustic signal. In addition, when the optimization problem is defined, a minimization objective function for determining the filter coefficient is set to a sum of squares of the error between the directional characteristic corresponding to the desired area and the directional characteristic observed at the control point. 2 norm and the sum of squares of the filter coefficients, 2 norm and a mixture l that evaluates the sparsity of the sound field in the area being reproduced. 1,2 The optimization problem is defined by adding the norm as an operator. Effect of the Invention

[0014] According to one aspect of the present invention, it is possible to provide a technique that can suppress the generation of acoustic side lobes in directions other than the intended direction while suppressing the amplitude of an acoustic drive signal supplied to a speaker array. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an area reproduction system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing an example of a hardware configuration of a playback control device provided in the system shown in FIG. [Diagram 3] FIG. 3 is a block diagram showing an example of a software configuration of a playback control device provided in the system shown in FIG. [Figure 4]FIG. 4 is a flowchart showing an example of a processing procedure and processing contents performed by the playback control device shown in FIG. [Diagram 5] FIG. 5 is a diagram showing an observation system for explaining an example of a directivity control filter setting technique using the least squares method. [Figure 6] FIG. 6 is a diagram showing an observation system for explaining an example of the acoustic contrast maximization technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] [One embodiment] (Configuration example) (1) System FIG. 1 is a diagram showing the overall configuration of an area reproduction system according to an embodiment of the present invention. An area reproduction system according to one embodiment includes a speaker array SP arranged corresponding to an area, a reproduction control device 1 that supplies an acoustic drive signal BS to the speaker array SP, and an input / output device 2 connected to the reproduction control device 1.

[0018] The speaker array SP is made up of multiple speakers SP1 to SP L The speakers are arranged in a line, for example, with their sound emission directions facing in the same direction. In FIG. 1, they are arranged in a straight line. L The arrangement of the speakers may be a ring or arc shape with the sound emission direction of each speaker facing outward, or a rectangular shape. L The placement and sound emission direction can be set arbitrarily.

[0019] The speaker array SP is driven by an acoustic drive signal BS supplied from the playback control device 1 (described later) and emits sounds converged in a controlled direction. u1 ~CP u3 In addition, in Fig. 1, CPu1 ~CP u3 Control points other than CP1 to CP M indicates the control points that correspond to the non-target areas in this example.

[0020] The input / output device 2 is, for example, a personal computer or a mobile terminal such as a smartphone used by a system administrator or a user, and is used to specify a target area for the playback control device 1. The input / output device 2 may be, for example, a television remote control or an operation panel of a car navigation device, and the connection means between the input / output device 2 and the playback control device 1 may be a wireless interface such as Bluetooth (registered trademark), WiFi (registered trademark), or a mobile communication network other than a wired cable.

[0021] (2) Playback control device 1 2 and 3 are block diagrams showing the hardware and software configurations, respectively, of the playback control device 1. As shown in FIG.

[0022] The playback control device 1 includes a control unit 10 using a hardware processor such as a central processing unit (CPU). A storage unit having a program storage unit 20 and a data storage unit 30, an input / output interface (hereinafter, the interface is referred to as an I / F) 40 to which the input / output device 2 is connected, and an audio signal I / F 50 are connected to the control unit 10 via a bus 60.

[0023] The audio signal I / F 50 is used to input an audio signal output from a sound source (not shown) and to output an audio drive signal BS generated by a control unit 10 (described later) to the speaker array SP.

[0024] The program storage unit 20 is configured, for example, by combining a non-volatile memory such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) as a storage medium that can be written to and read at any time, and a non-volatile memory such as a ROM (Read Only Memory), and stores programs necessary for executing various control processes according to one embodiment, in addition to middleware such as an OS (Operating System).

[0025] The data storage unit 30 is, for example, a combination of a non-volatile memory such as an HDD or SSD, which can be written to and read from at any time, as a storage medium, and a volatile memory such as a RAM (Random Access Memory), and is equipped with an area designation data storage unit 31 and a filter coefficient storage unit 32 as main storage units required to implement one embodiment.

[0026] The area designation data storage unit 31 is used to store the area designation data DS input from the input / output device 2 to the playback control device 1. The filter coefficient storage unit 32 is used to store the filter coefficient of the directivity control filter calculated by the control unit 10.

[0027] The control unit 10 includes, as processing functions necessary for carrying out one embodiment, an area designation data input processing unit 11, an optimization problem definition processing unit 12, a directivity control filter design processing unit 13, and a convolution calculation processing unit 14. All of these processing units 11 to 14 are realized by causing a hardware processor of the control unit 10 to execute a program stored in a program storage unit 20.

[0028] The area designation data input processing unit 11 receives the area designation data DS output from the input / output device 2 via the input / output I / F 40, and performs processing to store the received area designation data DS in the area designation data storage unit 31.

[0029] The optimization problem definition processing unit 12 receives area designation data DS from the input / output device 2 and a plurality of control points CP1 to CP M Based on matrix A, which indicates the weights to be given to the above, a process is performed to define an optimization problem for reproducing sound in a specific target area.

[0030] The directivity control filter design processing unit 13 performs processing to design a directivity control filter using a proximity separation algorithm based on the optimization problem defined by the optimization problem definition processing unit 12, and stores the filter coefficients calculated by this processing in the filter coefficient storage unit 32.

[0031] The convolution calculation processing unit 14 performs a convolution calculation on the acoustic signal AS input via the acoustic signal I / F 50 and the filter coefficients stored in the filter coefficient storage unit 32. Then, the speakers SP1 to SP L The acoustic drive signal BS having a controlled phase and amplitude is then output from the acoustic signal I / F 50 to the corresponding speakers SP1 to SP L The process of outputting to is performed.

[0032] (Example of operation) In order to facilitate understanding of the area reproduction control technology according to one embodiment of the present invention, we will first explain examples of directivity control technology and acoustic contrast maximization technology, which are the prerequisite technologies for the area reproduction control technology according to the present invention, and then explain the filter gain suppression technology using a penalty term described in Non-Patent Document 1 and the side lobe suppression technology using the weighted least squares method described in Non-Patent Document 2.

[0033] (1) Directivity control technology As mentioned above, sound directional control technology using a speaker array involves placing control points around a speaker array consisting of multiple speakers lined up, designing a filter that controls the amplitude and phase of each speaker based on the transmission characteristics from the speaker to the control point, and supplying an acoustic drive signal BS that reflects the filter coefficient of the filter to the speaker, thereby controlling the direction in which sound propagates strongly from the speaker, or the direction in which sound does not propagate.

[0034] A representative method for designing a filter for directivity control is a method using the least squares method. Fig. 5 shows an example of an observation system for explaining a design method of a directivity control filter using the least squares method. Note that Fig. 5 shows an example in which speakers are arranged in a ring shape, but the configuration of the speaker array is not limited to this, and various configurations are possible.

[0035] Now each speaker SP1~SP L The vector set in the directional control filter corresponding to

number

number

[0036] Then, the signal d^(ω) can be expressed as follows:

number

[0037]

number

[0038] The least squares method for calculating the filter coefficients of the directivity control filter is the sum of squares of the error between the desired directivity characteristic d(ω) and the directivity characteristic d^(ω) observed at the control point, ||e(ω)|| 2 This becomes a minimization problem to find the filter coefficient w(ω) that minimizes

[0039] Therefore, the objective function J to be minimized is expressed by the following equation.

number

[0040] By solving the problem of minimizing the objective function J expressed by equation (2) for the filter coefficient w(ω), the filter coefficient w(ω) of the directivity control filter is obtained as follows.

number

[0041] (2) Acoustic contrast maximization technology As mentioned above, the acoustic contrast maximization technique is a technique for maximizing the sound pressure ratio between a bright zone and a dark zone that are arbitrarily set using a speaker array.

[0042] Figure 6 shows an example of an observation system used to explain the acoustic contrast maximization technology. Note that, although Figure 6 also shows an example in which speakers are arranged in a ring shape, the configuration of the speaker array is not limited to this, and various configurations are possible.

[0043] First, the desired sound field, that is, the Bright-zone BZ that reproduces sound and the Dark-zone DZ that suppresses sound, are arbitrarily set. mB ~CP MB , CP1~CP mD ~CP MD indicate the control points defined for the Bright-zone BZ and Dark-zone DZ above, respectively. When the speaker array SP is driven by an acoustic drive signal whose phase and amplitude are controlled for each speaker by a filter, the sound field observed in each area can be expressed by the following equation.

number

[0044] In addition, the acoustic energy E in the Bright-zone BZ and the Dark-zone DZ B (ω), E D (ω) can be expressed by the following equation:

number

[0045] The acoustic contrast AC is the acoustic energy E B and E D It is expressed as a ratio to:

number

[0046] The acoustic contrast maximization technique is defined as the following optimization problem to maximize the acoustic contrast AC given by equation (9):

number

[0047] (3) Filter gain suppression technology using penalty terms When designing a filter that controls area reproduction, the filter coefficients are set so that the acoustic drive signal includes a filter gain. Here, the l-th speaker SP l The filter gain F l gain (ω) is defined as follows:

number

[0048] Here, w l (ω) is the lth speaker SP l The filter coefficients correspond to the filter gains of the two types of filters. The superscript * indicates the complex conjugate. If the filter gain is large, the amplitude of the acoustic drive signal supplied to the speaker will also be large in proportion to the filter gain, which will place a large load on the speaker, making it difficult to reproduce the sound. It will also cause clipping of the sound.

[0049] In contrast, in the filter gain suppression technique using a penalty term, a filter that controls area reproduction is designed by adding a penalty term to the objective function. In this case, for example, the sum of squares of the filter coefficients is used as the penalty term to suppress the filter gain.

[0050] Consider a filter for area reproduction control when a penalty term is used, taking as an example a filter to which directional control using the least squares method is applied. When the penalty term is applied to the objective function J shown in the above formula (3),

number

[0051] where β(ω) is the regularization parameter and the loss term ||e|| 2 and the penalty term ||e(ω)|| 2 This parameter controls the relative weighting of ω and ω. Similarly to equation (4), by solving the minimization problem for w(ω), the following directivity control filter coefficient w(ω)

number

[0052] (4) Sidelobe suppression technology using weighted least squares method The directivity control technology using the least squares method aims to minimize the sum of squares of the error between the sound field to be reproduced and the sound field that is actually reproduced. For this reason, side lobes, which are sound leakage in directions other than the intended direction, tend to occur.

[0053] Therefore, the side lobe is suppressed by setting a weight for the error at each control point. The objective function J of the weighted least squares method is expressed by the following equation, which adds the matrix A(ω) shown in equation (3).

number

[0054] Here, the weighting matrix A(ω) is a diagonal matrix, and for a control point for which it is desired to reduce the error from the desired sound field to be reproduced, a large weight should be assigned to the corresponding diagonal element. In other words, if it is desired to suppress side lobes, a large value should be assigned to the diagonal element corresponding to a direction different from the target direction, and if it is desired to make the sound field in the target direction closer to the desired sound field, a large value should be assigned to the diagonal element corresponding to the target direction.

[0055] That is, by solving the problem of minimizing the objective function J expressed by equation (14) for w(ω), the filter coefficient w(ω) of the weighted directivity control filter as follows is obtained:

number

[0056] (5) Area Regeneration Control in an embodiment of the present invention FIG. 4 is a flowchart showing the procedure and contents of the area playback control process executed by the playback control device 1.

[0057] (5-1) Entering area designation data A system administrator or a user designates an area in which sound is desired to be reproduced on the input / output device 2. In response to this designation operation, the input / output device 2 generates area designation data DS, and the generated area designation data DS is sent to the reproduction control device 1. In this example, the control points CP1 to CP M Of these, the control point CP u1 ~CP u3 As an example, a case will be described in which an area corresponding to the area 100 is designated as a specific area in which sound reproduction is desired.

[0058] In response to this, when the control unit 10 of the playback control device 1 detects in step S10 an area designation request sent from the input / output device 2 prior to the area designation data DS, under the control of the area designation data input processing unit 11, in step S11 it imports the area designation data DS via the input / output I / F 40 and stores the imported area designation data DS in the area designation data memory unit 31.

[0059] (5-2) Definition of the optimization problem When the control unit 10 of the playback control device 1 receives the area designation data DS, it then, under the control of the optimization problem definition processing unit 12, in step S12 defines an optimization problem for playing back sound in a specific target area as follows:

[0060] That is, the optimization problem definition processing unit 12 reads the area designation data from the area designation data storage unit 31, and compares the read area designation data DS with each of the control points CP1 to CPM Based on the matrix A consisting of weights to be assigned to the above, an optimization problem for reproducing sound for a specific area designated by the area designation data DS is defined.

[0061] For example, suppose the sound field in the area specified by the area specification data DS is d=[d1, d2, ..., d M ] T Then, the optimization problem is

number

[0062] Here, G is the number of L speakers SP1 to SP2 that make up the speaker array SP. L M control points CP1 to CP M A transfer function matrix with M columns and L rows that stores the transfer functions up to and including the speakers SP1 to SP L The filter coefficient vector [w1, w2, … , w L ] T In addition, λ1 and λ2 are the sum of squares of the l2 norm (||·|| 2 ) and mixed 1,2 Norm (||| 1,2 ), and u is the hyperparameter that controls the reproduced sound field [u1,u2, … ,u M ] T Shows.

[0063] (5-3) Design of directivity control filters Next, in step S13, the control unit 10 of the playback control device 1, under the control of the directivity control filter design processing unit 13, calculates a directivity control filter by solving the optimization problem defined by the optimization problem definition processing unit 12 using a proximity separation algorithm.

[0064] For example, in step S131, the directivity control filter design processing unit 13 first defines the optimization problem defined by the optimization problem definition processing unit 12 as follows for simplicity:

number

[0065] Then, the above optimization problem

number

[0066] Next, in step S132, the directivity control filter design processor 13 generates the following proximity separation algorithm for the optimization problem shown in the rewritten equation (17), based on the fixed-point condition that the subdifferentials with respect to the primal variable w and the dual variable p include 0.

number

[0067] Then, the directivity control filter design processing unit 13 applies the Nesterov acceleration method to the generated algorithm and the PROX γ2,λ2h* Applying the Moreau expansion to (p+γ2Gw), we obtain the algorithm shown below.

number

[0068] Next, in step S133, the directivity control filter design processing unit 13 executes the above algorithm to calculate the filter coefficient w of the directivity control filter. max The execution of the algorithm is stopped when the directivity control filter design processing unit 13 stores the calculated filter coefficient w 1 of the directivity control filter in the filter coefficient storage unit 32.

[0069] (5-3) Reflection of filter coefficients to input audio signals When the calculation and storage process of the filter coefficient w 1 of the directivity control filter is completed, the control unit 10 of the playback control device 1 thereafter executes the playback process of the sound for the specific area as follows.

[0070] That is, the control unit 10 of the playback control device 1 receives an audio signal AS output from a sound source (not shown) through the audio signal I / F 50. At this time, if the audio signal AS is an analog signal, it is converted into a digital signal by the audio signal I / F 50. Next, under the control of the convolution calculation processing unit 14, the control unit 10 of the playback control device 1 performs a convolution calculation of the audio signal AS received through the audio signal I / F 50 and the filter coefficient w stored in the filter coefficient storage unit 32 in step S14, thereby outputting a signal to the speakers SP1 to SP2 reflecting the filter coefficient w. L The generated acoustic signal is converted into an analog signal by the acoustic signal I / F 50, and then output as an acoustic drive signal BS to the corresponding speakers SP1 to SP L is output to.

[0071] (effect) As described above, in the playback control device 1 according to an embodiment of the present invention, the optimization problem definition processing unit 12 calculates information representing a sound field in a desired area specified by the input area specification data DS, and each of the control points CP1 to CP M The optimization problem for reproducing sound in the desired area is defined based on a matrix A indicating the weighting to be given to the filter coefficient vectors. In this case, the optimization problem includes the sum of squares l2 norm of the filter coefficient vectors and a mixed l2 norm that evaluates the sparsity of the sound field in the reproduction area. 1,2The norm is added to the objective function as the sum of operators. Then, in the directivity control filter design processing unit 13, the defined optimization problem is solved by a proximity separation algorithm to calculate the filter coefficient w of the directivity control filter. Thereafter, in the convolution calculation processing unit 14, the input acoustic signal AS is convoluted with the calculated filter coefficient w of the directivity control filter to generate an acoustic drive signal BS for each speaker, and each generated acoustic drive signal BS is sent to the corresponding speaker SP1 to SP2. L By supplying the signal to the desired area, sound can be played back in the desired area.

[0072] That is, in one embodiment, when designing a directivity control filter, in an objective function for calculating a filter coefficient w of the directivity control filter by the least squares method, a desired directivity characteristic and control points CP1 to CP M The sum of squares of the error between the observed directional characteristics and the mixed l2 norm is added to the sum of squares of the filter coefficients (l2 norm) as a penalty term, and the sound field in the playback area is assumed to have sparseness. 1,2 The norm is added as an operator.

[0073] Therefore, each speaker SP1 to SP L It is possible to effectively suppress sound leakage to surrounding areas other than the desired area, that is, the occurrence of side lobes, while suppressing the amplitude of the acoustic driving signal BS supplied to the desired area.

[0074] [Other embodiments] It should be noted that the present invention is not limited to the above embodiment. For example, in one embodiment, the optimization problem definition process, directivity control filter design process, and convolution calculation process executed by the playback control device 1 are all realized by having a hardware processor (CPU) execute a program. However, some or all of these functions may be realized by using an integrated circuit configured for a specific application, such as an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Processor).

[0075] In addition, the functional configuration of the playback control device, the configuration of the speaker array, the location of the area and the means for specifying it, etc. may be modified in various ways without departing from the spirit and scope of the present invention.

[0076] In short, this invention is not limited to the above-mentioned embodiment as it is, and in the implementation stage, the components can be modified and embodied without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining multiple components disclosed in the above-mentioned embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0077] SP1~SP L …Speaker CP1~CP M …Control points 1...Playback control device 2. Input device 10...Control section 11...Area-specific data input processing section 12...Optimization problem definition processing section 13...Directivity control filter design processing section 14...Convolution processing unit 20...Program memory section 30...Data storage unit 31...Area designation data storage unit 32...Filter coefficient storage section 40...Input / output interface 50...Acoustic signal I / F

Claims

1. An area reproduction system comprising a speaker array configured by arranging a plurality of speakers, and a reproduction control device connected to the speaker array, the reproduction control device individually driving the plurality of speakers with an acoustic drive signal whose phase and amplitude are controlled for the speaker array, thereby reproducing sound in a desired area, The playback control device includes: an optimization problem definition processing unit that acquires area designation information that designates the desired area, and defines an optimization problem for reproducing sound for the desired area based on the acquired area designation information and weight information to be assigned to a plurality of control points defined in the area; a directivity control filter design processing unit that calculates, for each of the plurality of speakers, a filter coefficient that controls an acoustic directivity characteristic of the speaker array by solving the defined optimization problem using a proximity separation algorithm; a drive signal generation processing unit that generates the acoustic drive signal by reflecting the calculated filter coefficient in an input acoustic signal; Equipped with The optimization problem definition processing unit defines the optimization problem by adding, as operators to a minimization objective function for determining the filter coefficients, an l 2 norm indicating the sum of squares of the error between the directional characteristic corresponding to the desired area and the directional characteristic observed at the control point, an l 2 norm indicating the sum of squares of the filter coefficients, and a mixed l 1,2 norm evaluating the sparseness of the sound field in the area to be reproduced. Area regeneration system.

2. A playback control device used to play back sound to a desired area, comprising: an optimization problem definition processing unit that acquires area designation information that designates the desired area, and defines an optimization problem for reproducing sound for the desired area based on the acquired area designation information and weight information to be assigned to a plurality of control points defined in the area; a directivity control filter design processing unit that calculates a filter coefficient for controlling an acoustic directivity characteristic of a speaker array by solving the defined optimization problem using a proximity separation algorithm; a drive signal generation processing unit that generates an acoustic drive signal for driving the speaker array by reflecting the calculated filter coefficient in an input acoustic signal; Equipped with The optimization problem definition processing unit defines the optimization problem by adding, as operators to a minimization objective function for determining the filter coefficients, an l 2 norm indicating the sum of squares of the error between the directional characteristic corresponding to the desired area and the directional characteristic observed at the control point, an l 2 norm indicating the sum of squares of the filter coefficients, and a mixed l 1,2 norm evaluating the sparseness of the sound field in the area to be reproduced. Playback control device.

3. The playback control device according to claim 2 , wherein the drive signal generation processing unit generates the acoustic drive signal by performing a convolution operation on the input acoustic signal and the calculated filter coefficient.

4. 1. A playback control method executed by an information processing device to play back sound in a desired area, comprising: acquiring area designation information designating the desired area, and defining an optimization problem for reproducing sound for the desired area based on the acquired area designation information and weight information to be assigned to a plurality of control points defined in the area; A step of calculating filter coefficients for controlling the acoustic directivity characteristics of a speaker array by solving the defined optimization problem using a proximity separation algorithm; generating an acoustic drive signal for driving the speaker array by reflecting the calculated filter coefficient in an input acoustic signal; Equipped with The step of defining the optimization problem includes adding, as operators to a minimization objective function for determining the filter coefficients, an l 2 norm indicating the sum of squares of the error between the directional characteristic corresponding to the desired area and the directional characteristic observed at the control point, an l 2 norm indicating the sum of squares of the filter coefficients, and a mixed l 1,2 norm evaluating the sparsity of the sound field in the area to be reproduced. Playback control method.

5. A program for causing a processor included in the playback control device to execute the processes performed by the processing units included in the playback control device according to claim 2 or 3.

Images