Information processing apparatus, method, and program

Abstract

The present technology relates to an information processing apparatus, method, and program that enable sound field control having a higher degree of freedom. The information processing method of the present invention involves an information processing apparatus performing the following: identifying a parameter relating to the complex acoustic impedance of a resonator, or a sound absorber that uses the resonator, installed on a surface forming a target space, said parameter being identified on the basis of a target sound pressure frequency characteristic at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristic at any point in the target space; and identifying the shape of the sound absorber on the basis of the parameter. The present technology can be applied to an acoustic metamaterial.

Description

Information Processing Apparatus and Method, and Program

[0001] The present technology relates to an information processing apparatus and method, and a program, and particularly to an information processing apparatus and method, and a program capable of realizing a higher degree of freedom in sound field control.

[0002] For example, by installing sound absorbers such as acoustic metamaterials on the walls and ceilings of a target space such as a vehicle interior, it is possible to realize sound field control of the target space, such as reducing road noise and engine noise in the vehicle interior.

[0003] As such a technology, a technology has been proposed in which a plurality of acoustic metamaterials having different frequencies of sound to be absorbed are arranged so as to be able to cope with noises in various frequency bands (see, for example, Patent Document 1).

[0004] International Publication No. 2024 / 048130

[0005] Generally, when designing a sound absorber installed in a space (target space) to be controlled for sound field, the shape of the sound absorber and the like are determined by maximizing the sound absorption rate of the sound absorber. Therefore, there are cases where sound field control cannot be performed with a sufficiently high degree of freedom.

[0006] As an example, for example, when the target space for sound field control is a closed space, standing modes, that is, standing waves, are generated at a predetermined frequency in the target space.

[0007] In this case, it is difficult to completely suppress the standing mode even if the sound absorber is designed by maximizing the sound absorption rate, and since the positions of the nodes and antinodes of the standing mode in the target space are fixed positions, the degree of freedom in sound field control is reduced.

[0008] The present technology has been made in view of such a situation, and is intended to realize a higher degree of freedom in sound field control.

[0009] One aspect of this technology is an information processing device which includes a parameter identification unit that identifies parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator installed on the surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics at any point in the target space, and a shape identification unit that identifies the shape of the sound absorber based on the parameters.

[0010] One aspect of this technology is an information processing method or program which includes identifying parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator, which is installed on the surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics at any point in the target space, and identifying the shape of the sound absorber based on the parameters.

[0011] One aspect of this technology includes identifying parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator, which is installed on the surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics at any point in the target space, and identifying the shape of the sound absorber based on the parameters.

[0012] This is a diagram illustrating this technology. This is a diagram showing an example of the configuration of an information processing device. This is a flowchart illustrating the design process. This is a diagram illustrating the processing order of the design process. This is a flowchart illustrating the manufacturing process. This is a diagram illustrating an example of the application of this technology. This is a diagram illustrating an example of the application of this technology. This is a diagram illustrating an example of the application of this technology. This is a diagram showing an example of the configuration of a computer.

[0013] The following describes embodiments to which this technology is applied, with reference to the drawings.

[0014] <First Embodiment> <About this Technology> This technology enables more flexible sound field control by considering not only the sound absorption coefficient but also phase information, i.e., the reflection phase angle, when designing a sound absorber.

[0015] This technology is applicable to the design of sound absorbers using resonators (resonance systems) or acoustic resonators (resonance systems), but the following explanation will focus on the case where the sound absorber is an acoustic metamaterial.

[0016] For example, in controlling a sound field with standing modes in a closed space using a sound absorber, the standing modes are generally attenuated by maximizing the sound absorption coefficient of the sound absorber. In other words, the attenuation of standing modes is achieved through the sound absorption effect.

[0017] In this context, a standing mode is a stationary (steady) sound pressure distribution formed by sound waves in two-dimensional or three-dimensional space; for example, a standing wave is a standing mode.

[0018] On the other hand, this technology actively utilizes the change in the sound reflection phase angle at the design frequency of the acoustic metamaterial. Specifically, the complex acoustic impedance, consisting of the optimal sound absorption coefficient and reflection phase angle, is identified through optimization calculations, and the shape of the acoustic metamaterial is determined from the identification result.

[0019] This allows for the alteration of the shape of standing modes or the suppression of their excitation (generation) using acoustic metamaterials. Therefore, this technology makes it possible to achieve dramatic changes in sound pressure frequency characteristics, i.e., control of the sound field, at any evaluation point within the target space, that cannot be achieved by attenuation of standing modes due to sound absorption effects alone.

[0020] Furthermore, in this technology, a theoretical model is used in the design of acoustic metamaterials that can calculate the sound absorption coefficient and reflection phase angle of an acoustic metamaterial, for example, from parameters related to the shape of the acoustic metamaterial (hereinafter also referred to as shape parameters).

[0021] For example, the acoustic metamaterial designed using this technology is composed of multiple cells, each cell consisting of multiple Helmholtz resonators. In this case, the theoretical model can determine the sound absorption coefficient and reflection phase angle of the acoustic metamaterial corresponding to the shape parameters of each cell. More specifically, the theoretical model can be used to obtain parameters related to the complex acoustic impedance of the acoustic metamaterial based on the shape parameters.

[0022] Furthermore, regarding this technology, it was confirmed that the combination of sound absorption coefficient and reflection phase angle of each surface forming the target space, which fits the sound pressure frequency characteristics at any evaluation point within the target space to a desired curve, can be identified through numerical simulation optimization.

[0023] This technology combines the use of these theoretical models with the identification of sound absorption coefficient and reflection phase angle through optimization, making it possible to design the shape and arrangement of an acoustic metamaterial that yields the desired sound pressure frequency characteristics at any given evaluation point using numerical simulation.

[0024] Now, let me explain this technology in more detail.

[0025] In this technology, an acoustic metamaterial is designed to be installed in a desired space (hereinafter also referred to as the target space). In other words, in this technology, by designing an appropriate acoustic metamaterial and installing it on a predetermined surface within the target space, control of the sound field within the target space, or in other words, control of the sound pressure frequency characteristics, is achieved.

[0026] Specifically, let's assume, for example, that there is a target space 11 that is the subject of sound field control, as shown in Figure 1.

[0027] The target space 11 is, for example, a three-dimensional enclosed space such as a car interior. Furthermore, sound-absorbing acoustic metamaterials are installed on the walls, ceiling, floor, and other surfaces forming the target space 11. While this explanation describes an example where the target space 11 is an enclosed space, the target space 11 does not necessarily have to be an enclosed space; it can be any type of space.

[0028] In the example shown in Figure 1, an acoustic metamaterial 21-1 is installed on one wall surface of the target space 11, and an acoustic metamaterial 21-2 is installed on the ceiling of the target space 11.

[0029] In the following, unless there is a need to distinguish between acoustic metamaterial 21-1 and acoustic metamaterial 21-2, they will simply be referred to as acoustic metamaterial 21. Furthermore, although an example in which a sound absorber is an acoustic metamaterial will be described here, any sound absorber that uses a resonator or resonating chamber may be used.

[0030] Furthermore, in the following, among the surfaces forming the target space 11, such as walls and ceilings, the surface on which the acoustic metamaterial 21 is installed will also be referred to as the installation surface. The number of acoustic metamaterials 21 installed in the target space 11 may be one or multiple. For example, the acoustic metamaterials 21 may be installed so as to cover substantially the entire installation surface.

[0031] The acoustic metamaterial 21 is composed of multiple cells 31 arranged in a row. Although only one cell 31 is depicted here, in reality, multiple cells 31 are provided.

[0032] Cell 31 is a unit composed of multiple resonators. In this example, one cell 31 is composed of three resonators 32-1 to 32-3. Hereafter, unless there is a need to distinguish between resonators 32-1 to 32-3, they will simply be referred to as resonator 32.

[0033] For example, the resonator 32 is a Helmholtz resonator and has a neck 33 which is an opening and a cavity 34 which is a resonant chamber. In the resonator 32, when sound waves propagate from the outside to the neck 33, a resonance phenomenon occurs and the sound energy is reduced (attenuated).

[0034] The cell 31 may consist of one or more resonators 32. Furthermore, the cell 31 may contain multiple resonators 32 of different types. These different types of resonators 32 include, for example, resonators 32 with different resonant frequencies.

[0035] In this technology, the acoustic metamaterials 21 installed (placed) on each installation surface are designed so that desired sound field control can be achieved in the target space 11, that is, so that desired sound pressure frequency characteristics can be obtained at a specific position (point).

[0036] For example, suppose the target space 11 is a closed space, such as a car interior, and a predetermined area (space) within the target space 11 is defined as the listening area where the listener receives audio. In this case, the position within the listening area is defined as the evaluation point subject to sound field control. The shape of the acoustic metamaterial 21 is then designed so that the sound pressure frequency characteristics at the evaluation point have desired characteristics, such as a flat frequency response.

[0037] <Example of Information Processing Device Configuration> Figure 2 shows an example of the configuration of an information processing device to which this technology is applied.

[0038] The information processing device 61 shown in Figure 2 consists of, for example, a personal computer. Alternatively, the information processing device 61 may be composed of multiple devices, such as multiple servers that constitute a cloud.

[0039] The information processing device 61 includes an input unit 71, a display unit 72, a recording unit 73, and a control unit 74.

[0040] The input unit 71 consists of a mouse, keyboard, touch panel, etc., and supplies information to the control unit 74 according to the user's operation. The display unit 72 consists of a liquid crystal display, etc., and displays various images according to the control of the control unit 74.

[0041] The recording unit 73 consists of memory and other components, and records various types of data such as programs. For example, the recording unit 73 records data supplied from the control unit 74, and supplies the recorded data to the control unit 74.

[0042] The control unit 74 consists of a processor or the like and controls the operation of the entire information processing apparatus 61.

[0043] For example, the control unit 74 realizes the acoustic analysis model generation unit 81, the analysis processing unit 82, the parameter identification unit 83, the theoretical model generation unit 84, and the shape identification unit 85 by executing the program recorded in the recording unit 73.

[0044] The acoustic analysis model generation unit 81 generates a 3D acoustic analysis model for obtaining the sound pressure distribution in the entire target space based on the information on the target space where the acoustic metamaterial is installed, which is supplied from the input unit 71 in response to the input operation by the user. By using this 3D acoustic analysis model, the sound pressure frequency characteristics at an arbitrary position in the target space, that is, at an arbitrary point (evaluation point), can be obtained.

[0045] The 3D acoustic analysis model takes into account not only the sound absorption rate but also the reflection phase angle as the characteristics of the surfaces such as the wall surfaces forming the target space. Specifically, as the information constituting the 3D acoustic analysis model, it also includes the complex acoustic impedance of each surface forming the target space, that is, the parameters related to the sound absorption rate and the reflection phase angle. Basically, the target space is a three-dimensional space, but the target space may also be a two-dimensional space.

[0046] The analysis processing unit 82 performs a frequency response analysis based on the 3D acoustic analysis model and calculates the sound pressure for each frequency at the evaluation points in the target space, that is, the sound pressure frequency characteristics.

[0047] The parameter identification unit 83 identifies the complex acoustic impedance of each installation surface forming the target space, more specifically, the parameters related to the complex acoustic impedance (hereinafter also referred to as model parameters) by fitting processing using the 3D acoustic analysis model.

[0048] The model parameters are parameters indicating the complex acoustic impedance of the acoustic metamaterial. Specifically, for example, the model parameters are the resistance R, inductance L, and capacitance C when the complex acoustic impedance of the acoustic metamaterial (installation surface) is modeled by a series equivalent circuit of RLC (RLC series circuit).

[0049] The theoretical model generation unit 84 constructs (generates) a theoretical model for calculating model parameters indicating the complex acoustic impedance of the acoustic metamaterial from the shape of the acoustic metamaterial, more specifically, parameters (hereinafter also referred to as shape parameters) indicating the shape of the acoustic metamaterial.

[0050] For example, the shape parameters are parameters (information) indicating at least any one of a combination of different types of resonators constituting the cells of the acoustic metamaterial, the length of the neck of the resonator, the cross-sectional area of the neck, and the dimensions (volume) of the cavity constituting the resonator. Also, parameters (information) indicating the arrangement of a plurality of each cell in the acoustic metamaterial (cell arrangement pattern), the arrangement of a plurality of resonators constituting the cell (resonator arrangement pattern in the cell), etc. may also be regarded as shape parameters. The shape parameters may be any as long as they can specify the shape of the acoustic metamaterial.

[0051] The shape identification unit 85 identifies the shape of the acoustic metamaterial, that is, the shape parameters, based on the theoretical model and the model parameters identified by the parameter identification unit 83. The shape parameters identified by the shape identification unit 85 become the design result of the acoustic metamaterial.

[0052] <Explanation of design process> The operation of the information processing device 61 will be described. That is, hereinafter, the design process by the information processing device 61 will be described with reference to the flowchart of FIG. 3.

[0053] In step S11, the acoustic analysis model generation unit 81 generates a 3D acoustic analysis model of the target space based on the information supplied from the input unit 71 in response to the input operation by the user.

[0054] For example, the user, who is the designer, operates the input unit 71 while viewing the screen displayed on the display unit 72 as appropriate, and inputs information about the target space where the acoustic metamaterial will be installed (hereinafter also referred to as input information). For example, the target space is a closed space that has a standing mode, that is, a space in which a standing mode can occur.

[0055] Specifically, input information may include, for example, the three-dimensional shape (3D shape) and size of the target space, and the complex acoustic impedance (sound absorption coefficient and reflection phase angle) of each surface forming the target space. Furthermore, information about the sound source, such as the location of a predetermined sound source (e.g., a noise source) and the directional characteristics of the sound source, may also be input. For example, the sound source is assumed to have a flat sound pressure frequency response.

[0056] The acoustic analysis model generation unit 81 generates a 3D acoustic analysis model based on the input information supplied from the input unit 71. This model consists of information (parameters) indicating the three-dimensional shape and size of the target space, and the acoustic characteristics (complex acoustic impedance) of each surface forming the target space. At this point, the 3D acoustic analysis model represents the state before the acoustic metamaterial is installed (placed) in the target space.

[0057] Furthermore, during or after the generation of the 3D acoustic analysis model, the control unit 74 may supply image data to the display unit 72 so that the display unit 72 displays an image of the target space (an image that mimics the target space).

[0058] In step S12, the analysis processing unit 82 determines the evaluation points in the target space.

[0059] For example, the user operates the input unit 71 while referring to the image displayed on the display unit 72 as appropriate, and designates an arbitrary point (position) in the target space as an evaluation point. When the user makes a designation operation, the input unit 71 supplies information corresponding to the user's designation operation to the control unit 74.

[0060] The analysis processing unit 82 determines evaluation points in the target space based on information supplied from the input unit 71 in accordance with the user's specified operation. In other words, position information indicating the location of the evaluation points is generated.

[0061] In step S13, the analysis processing unit 82 performs frequency response analysis based on the 3D acoustic analysis model generated in step S11 and obtains the sound pressure frequency characteristics at the evaluation point determined in step S12.

[0062] For example, in frequency response analysis using a 3D acoustic analysis model, the distribution of sound pressure in the entire target space when sound (sound waves) is emitted from a given sound source can be calculated. From the calculation results of this distribution, the sound pressure frequency characteristics at the evaluation point can be obtained.

[0063] The sound pressure frequency characteristics of the evaluation point obtained in step S13 are those of the state before the acoustic metamaterial is installed (placed) on the surface forming the target space, that is, the state in which the acoustic metamaterial is not installed.

[0064] Furthermore, for example, the control unit 74 supplies image data such as a graph showing the sound pressure frequency characteristics at the evaluation point, which is the result of the frequency response analysis, to the display unit 72, and displays the sound pressure frequency characteristics at the evaluation point.

[0065] In step S14, the control unit 74 determines the target sound pressure frequency characteristics at the evaluation point based on the information supplied from the input unit 71.

[0066] The target sound pressure frequency response (SPR) is the target (ideal) SPR at the evaluation point. In other words, the target SPR can also be said to be the SPR after improvement at the evaluation point due to the installation of the acoustic metamaterial. In the design process, the shape (shape parameters) of the acoustic metamaterial is determined such that the SPR at the evaluation point after the installation of the acoustic metamaterial becomes as close as possible to the target SPR.

[0067] For example, the user operates the input unit 71 while referring to the sound pressure frequency characteristics of the evaluation points before the installation of the acoustic metamaterial displayed on the display unit 72, and specifies the target sound pressure frequency characteristics. In this case, it is conceivable that the target sound pressure frequency characteristics could be specified (input) by, for example, manipulating the displayed sound pressure frequency characteristics graph.

[0068] The control unit 74 determines the target sound pressure frequency characteristics of the evaluation point based on the information supplied from the input unit 71 in response to such user operations.

[0069] In step S15, the control unit 74 determines the installation surface for the acoustic metamaterial based on the information supplied from the input unit 71. That is, one or more of the surfaces that make up the target space are designated as the installation surface for the acoustic metamaterial.

[0070] For example, if an image of the target space (an image that mimics the target space) is displayed on the display unit 72, it is conceivable that the user can operate the input unit 71 to specify any surface on the image of the target space as the installation surface. In such a case, the control unit 74 will set the surface specified by the user as the installation surface based on the information supplied from the input unit 71 in response to the user's operation.

[0071] In step S16, the acoustic analysis model generation unit 81 models the complex acoustic impedance of the acoustic metamaterials to be installed on each installation surface using an RLC series equivalent circuit.

[0072] In other words, the acoustic analysis model generation unit 81 represents the absorption coefficient and reflection phase angle, which are the complex acoustic impedances of the acoustic metamaterial on the installation surface, using resistance R, inductance L, and capacitance C as model parameters.

[0073] The acoustic analysis model generation unit 81 replaces the complex acoustic impedance of the installation surface in the 3D acoustic analysis model generated in step S11 with model parameters obtained through modeling. In other words, the complex acoustic impedance of the installation surface (acoustic metamaterial) is modeled within the 3D acoustic analysis model. Furthermore, the complex acoustic impedance of surfaces other than the installation surface that form the target space may also be modeled, so that the complex acoustic impedance is replaced with model parameters.

[0074] It is known that using an RLC series equivalent circuit is appropriate for modeling the complex acoustic impedance of acoustic metamaterials using resonant or resonance systems. By performing such a model, the parameter identification unit 83 optimizes the design using model parameters of the installation surface in the target space, and more specifically, the acoustic metamaterial installed on the installation surface, as design variables.

[0075] In step S17, the parameter identification unit 83 identifies the model parameters of the series equivalent circuit corresponding to the complex acoustic impedance of the installation surface (acoustic metamaterial) based on the 3D acoustic analysis model obtained in step S16.

[0076] Specifically, the parameter identification unit 83 causes the analysis processing unit 82 to perform frequency response analysis based on the 3D acoustic analysis model to determine the sound pressure frequency characteristics at the evaluation point. In this case, the sound pressure frequency characteristics at the evaluation point are obtained as the sound pressure frequency characteristics (hereinafter also referred to as the applied sound pressure frequency characteristics) when the complex acoustic impedance of the acoustic metamaterial installed on the installation surface, i.e., the sound absorption coefficient and reflection phase angle, are set to arbitrary values.

[0077] More specifically, in this example, the complex acoustic impedance of the contact surface (acoustic metamaterial) is modeled using a series equivalent circuit. Therefore, the model parameters representing the complex acoustic impedance are set to arbitrary values, and frequency response analysis is performed to determine the applicable sound pressure frequency characteristics corresponding to the model parameters.

[0078] The parameter identification unit 83 changes the model parameters (complex acoustic impedance) of the acoustic metamaterial and performs frequency response analysis, and optimizes the system using the squared error between the applied sound pressure frequency characteristics and the target sound pressure frequency characteristics determined in step S14 as the objective function. In other words, optimization is performed using the model parameters as design variables.

[0079] The parameter identification unit 83 performs such optimization to identify model parameters that can obtain a target sound pressure frequency characteristic, or more specifically, a sound pressure frequency characteristic as close as possible to the target sound pressure frequency characteristic, as the sound pressure frequency characteristic at the evaluation point. In other words, the model parameters of each installation surface (acoustic metamaterial) that fit to the target sound pressure frequency characteristic, which is the target characteristic at the evaluation point, are identified by optimization calculation (fitting process).

[0080] In step S17, model parameters are identified for each installation surface, that is, for each acoustic metamaterial installed on each installation surface.

[0081] In step S18, the theoretical model generation unit 84 constructs (generates) a theoretical model that obtains model parameters for a series equivalent RLC circuit corresponding to the complex acoustic impedance of the acoustic metamaterial from the shape of the acoustic metamaterial, i.e., shape parameters that indicate the shape of the acoustic metamaterial.

[0082] In step S19, the shape identification unit 85 performs optimization calculations based on the theoretical model obtained in step S18 and identifies the shape (shape parameters) of the acoustic metamaterial that realizes the model parameters identified in step S17. In step S19, the shape is identified for each acoustic metamaterial.

[0083] Using a theoretical model, model parameters corresponding to the shape parameters of the acoustic metamaterial can be calculated based on those shape parameters. Furthermore, the model parameters identified in step S17 (hereinafter also referred to as target model parameters) are parameters that represent the complex acoustic impedance of the acoustic metamaterial that is ultimately to be obtained.

[0084] The shape identification unit 85 changes the shape parameters of the acoustic metamaterial and, based on a theoretical model, calculates the model parameters corresponding to each shape parameter. This identifies the shape parameters that allow for obtaining the target model parameters, or more specifically, the model parameters that are as close as possible to the target model parameters. In other words, the shape identification unit 85 uses the difference between the model parameters calculated based on the theoretical model and the target model parameters as the objective function, and performs an optimization calculation with the shape parameters as design variables to identify the shape parameters of the acoustic metamaterial that correspond to the target model parameters.

[0085] The shape parameters obtained through the process in step S19 are parameters that indicate the shape of the acoustic metamaterial that can obtain the target acoustic characteristics, i.e., the target sound pressure frequency characteristics, at the evaluation point in the target space. Once the shape parameters are identified, the design process is completed.

[0086] As described above, the information processing device 61 uses a 3D acoustic analysis model and a theoretical model to identify the shape of the acoustic metamaterial through simulation calculations (optimization). In other words, the information processing device 61 designs the acoustic metamaterial.

[0087] In particular, the information processing device 61 can achieve more flexible sound field control by considering not only the sound absorption coefficient of the acoustic metamaterial but also the reflection phase angle.

[0088] In other words, the information processing device 61, by designing the acoustic metamaterial including not only the sound absorption coefficient but also the reflection phase angle, can achieve a greater degree of freedom in controlling the sound pressure frequency characteristics (sound field control) than by designing solely to maximize the sound absorption coefficient.

[0089] Specifically, for example, when designing an acoustic metamaterial by maximizing its sound absorption coefficient, it is possible to attenuate standing modes generated in the target space. However, if complete sound absorption is not achieved, some standing modes will inevitably occur. In such cases, if the position of the evaluation point in the target space coincides with the position of a node in the sound pressure (standing mode) at a given frequency, a dip will occur in the sound pressure frequency characteristics at the evaluation point.

[0090] On the other hand, the information processing device 61 is designed taking into account not only the sound absorption coefficient but also the reflection phase angle. In this case, by changing (altering) the reflection phase angle, it is possible to change the shape of the standing modes generated in the target space.

[0091] Therefore, by design, for example, an acoustic metamaterial can be obtained such that the position of a desired evaluation point in the target space does not coincide with the position of a standing mode (sound pressure) node. In other words, the position of the standing mode nodes in the target space can be shifted so that there are no nodes at the evaluation point.

[0092] Furthermore, the same principle applies to the antinodes of standing modes (sound pressure) as it does to the nodes of standing modes. In addition, in principle, it is possible to design acoustic metamaterials such that the nodes and antinodes of standing modes are located at any evaluation point within the target space.

[0093] As described above, the information processing device 61 can identify model parameters corresponding to appropriate complex acoustic impedances (sound absorption coefficient and reflection phase angle), and then identify shape parameters according to the identification results. This enables more flexible sound field control, such as designating any position in the target space as a node or antinode of a standing mode. In other words, it can effectively control the sound pressure frequency characteristics at any evaluation point.

[0094] Furthermore, acoustic metamaterials that utilize resonant systems such as Helmholtz resonators are known as relatively small sound absorbers. Therefore, by using acoustic metamaterials as sound absorbers installed in a target space, it becomes possible to control the sound field, i.e., control the sound pressure frequency characteristics, down to low frequencies with relatively small sound absorbers.

[0095] As described above, this technology can be used in a variety of cases, such as creating a sound field suitable for playing music through speakers in a target space, or as a countermeasure against the phenomenon in which noise flowing from the external space into the target space is amplified by standing modes.

[0096] In the design process, it is not necessary for each step to be performed in the order explained with reference to Figure 3; two or more processes may be executed in parallel, or the order of some processes may be changed.

[0097] Specifically, as shown in Figure 4, for example, the processes in step S11 and step S12 only need to be completed before the process in step S13 is performed. That is, the processes in step S11 and step S12 may be executed in parallel, or the process in step S12 may be executed before the process in step S11.

[0098] Alternatively, the 3D acoustic analysis model may be generated in advance or acquired from an external source and stored in the control unit 74 or recording unit 73, such that the processing in step S11 is performed before the start of the design process.

[0099] Note that the processes in steps S11 to S19 shown in Figure 4 are the same as the processes in steps S11 to S19 shown in Figure 3.

[0100] Each of the processes in steps S13 to S16 only needs to be completed before the process in step S17 is performed. Therefore, for example, the processes in steps S15 and S16 may be performed before the processes in steps S13 and S14.

[0101] Furthermore, the processes in steps S17 and S18 only need to be completed before the process in step S19 is performed. For example, the process in step S17 may be performed after the process in step S18, or the processes in steps S17 and S18 may be performed in parallel.

[0102] Furthermore, the theoretical model may be generated in advance or acquired from an external source and stored in the control unit 74 or recording unit 73, such that the processing in step S18 is performed before the start of the design process.

[0103] <Explanation of Manufacturing Process> Once the shape parameters of each acoustic metamaterial are obtained through the design process by the information processing device 61, a manufacturing process is then carried out to manufacture the acoustic metamaterial based on the shape parameters. Note that some or all of the design process described with reference to Figure 3 may also be performed as part of the manufacturing process.

[0104] The manufacturing process is carried out by a manufacturing apparatus consisting of one or more devices, such as a processing device that generates each part of the resonator by molding, a joining device that arranges and joins multiple resonators or cells, and a computer device that controls the operation of these processing and joining devices.

[0105] The manufacturing process using the manufacturing equipment will be explained below with reference to the flowchart in Figure 5.

[0106] In step S61, the manufacturing apparatus obtains the shape parameters of the acoustic metamaterial from the information processing device 61.

[0107] In step S62, the manufacturing apparatus generates resonators that constitute the cells of the acoustic metamaterial based on the shape parameters acquired in step S61. That is, necks and cavities with the shapes indicated by the shape parameters are formed by processing, and resonators consisting of these necks and cavities are generated.

[0108] In step S63, the manufacturing apparatus, using shape parameters as necessary, arranges the multiple resonators obtained in step S62 to form a cell, and then performs necessary processing such as joining the multiple cells to generate an acoustic metamaterial. Once the acoustic metamaterial is generated, the manufacturing process is completed.

[0109] As described above, the manufacturing apparatus generates acoustic metamaterials based on shape parameters. By placing these resulting acoustic metamaterials in the target space, more flexible sound field control can be achieved.

[0110] <Application Example 1> The acoustic metamaterial of this technology can be used in various cases, such as adjusting the sound field to maximize the effect of noise cancellation (NC) technology. The following describes an example of the application of this technology, that is, a specific example of the application of the acoustic metamaterial obtained using this technology.

[0111] As the first example, we will explain an application of actuators to NC technology.

[0112] In this example, indirectly controlling the vibration modes of the wall surface through sound field control using acoustic metamaterials is expected to contribute to improving the efficiency of vibration control by actuators.

[0113] For example, in NC technology that uses actuators to suppress vibrations in window glass, it is necessary to use a large number of actuators to accommodate the distribution of vibration modes. In this case, the cost increases because many actuators need to be installed.

[0114] Therefore, as shown in Figure 6, for example, by installing acoustic metamaterials within the target space, the number of actuators can be reduced, thereby lowering costs.

[0115] In the example shown in Figure 6, a glass pane 121, such as a window pane, is provided on a part of the surface forming the target space 111. The target space 111 can be any type of space, such as a closed space.

[0116] Furthermore, actuators 122-1 and 122-2 for NC targeting the target space 111 are installed on the glass 121. These actuators 122-1 and 122-2 are driven by drive control units 123-1 and 123-2.

[0117] Hereafter, when there is no need to distinguish between actuator 122-1 and actuator 122-2, they will simply be referred to as actuator 122. Similarly, hereafter, when there is no need to distinguish between drive control unit 123-1 and drive control unit 123-2, they will simply be referred to as drive control unit 123.

[0118] The drive control unit 123 operates (drives) the actuator 122 according to the control unit 124, thereby suppressing vibrations of the glass 121.

[0119] Furthermore, acoustic metamaterials 125-1 and 125-2, designed by the design process in Figure 3 and manufactured by the manufacturing process in Figure 5, are installed on the surface forming the target space 111. Hereinafter, when there is no need to distinguish between acoustic metamaterials 125-1 and 125-2, they will simply be referred to as acoustic metamaterial 125.

[0120] Although an example is shown here in which two acoustic metamaterials 125 are installed, the number and location of the acoustic metamaterials 125 can be any number or location.

[0121] In this example, a noise-canceling system consisting of an actuator 122, a drive control unit 123, a control unit 124, and an acoustic metamaterial 125 reduces the noise generated in the target space 111.

[0122] Since the glass 121 vibrates in strong coupling with the sound field of the adjacent space, it is presumed that the vibration mode of the glass surface (glass 121) can be indirectly controlled by controlling the sound field using the acoustic metamaterial 125.

[0123] For example, if the nodes of a standing wave (standing mode) occurring indoors, i.e., within the target space 111, are facing the glass 121, then the sound field on both sides of the node will have an inverted phase, and the glass 121 (glass surface) facing that sound field will also have a divided mode. In this case, actuators 122 to suppress the vibration of the glass 121 need to be placed in each divided region. That is, a large number of actuators 122 need to be installed.

[0124] By installing the sound-absorbing acoustic metamaterial 125, the sound field within the target space 111 can be controlled, and if the position of the standing mode nodes can be shifted to a position away from the glass 121 (glass surface), the vibration of the glass 121 can be excited in a form close to the first mode.

[0125] Therefore, by designing an acoustic metamaterial 125 with a shape such that the positions of the standing mode nodes are different from those of the glass 121, and installing such an acoustic metamaterial 125 on a surface such as the ceiling of the target space 111, the number (number of installations) of actuators 122 that suppress the vibration of the glass 121 can be reduced. This method is particularly effective at frequencies below the eigenvalues ​​of the glass 121 that become divided modes.

[0126] <Application Example 2> As a second example, we will explain an application to NC technology using a speaker.

[0127] In this example, noise cancellation is achieved in the target space, or more specifically, in the area around the installation location of the error microphone within the target space, by outputting sound from a speaker installed within the target space. Figure 7 shows a specific example of the application of speaker-based noise cancellation technology.

[0128] In the example shown in Figure 7, the noise-canceling system 161 includes an error microphone 171, a sensor unit 172, a control unit 173, a speaker 174, and an acoustic metamaterial 175. In particular, the error microphone 171, the speaker 174, and the acoustic metamaterial 175 are arranged within the target space 176 that is to be noise-canceled.

[0129] In this example, the target space 176 is the space inside the vehicle, i.e., the passenger compartment. While the target space 176 is assumed to be a closed space here, it is not limited to a closed space; it can be any type of space.

[0130] The error microphone 171 is a microphone, sometimes called an error microphone, that is placed at a predetermined position within the target space 176. It picks up ambient sounds and supplies the resulting sound-collected signals to the control unit 173.

[0131] The sensor unit 172 consists of an acceleration sensor positioned near a noise source, such as near the chassis, in a vehicle having a target space 176 which is the passenger compartment. In this case, the noise (road noise) generated in the target space 176 when vibrations in the vicinity of the sensor unit 172 are transmitted to the target space 176 is the target of noise cancellation.

[0132] The sensor unit 172 detects ambient vibrations as noise and supplies the resulting sensor signal to the control unit 173. The sensor signal may be, for example, a signal indicating the acceleration characteristics at the installation location of the sensor unit 172.

[0133] The control unit 173 generates a cancellation signal to cancel noise observed at the position where the error microphone 171 is located, based on the sound pickup signal supplied from the error microphone 171 and the sensor signal supplied from the sensor unit 172.

[0134] For example, the control unit 173 generates and maintains a noise-canceling filter (NC filter) based on the sound transmission characteristics from the speaker 174 to the error microphone 171, which have been obtained by prior measurement, and the vibration (noise) transmission characteristics from the placement position of the sensor unit 172 to the placement position of the error microphone 171. This NC filter is a filter that cancels out the characteristics obtained by convolving the above-mentioned noise transmission characteristics with the noise characteristics (acceleration characteristics) observed by the sensor unit 172.

[0135] The control unit 173 generates a cancellation signal by performing filtering on the sensor signal supplied from the sensor unit 172 based on the NC filter it holds, and supplies the obtained cancellation signal to the speaker 174.

[0136] More specifically, the control unit 173 updates the previously held NC filter based on the sequentially supplied sound-gathering signals. For example, the control unit 173 updates the NC filter based on the rate of change of sound indicated by the sequentially supplied sound-gathering signals. The transmission characteristics of vibration (noise) from the position of the sensor unit 172 to the position of the error microphone 171 may also be used to update the NC filter.

[0137] The control unit 173 performs filtering on the sensor signal at each timing based on the latest NC filter (updated NC filter).

[0138] The speaker 174 outputs sound based on the cancellation signal supplied from the control unit 173, thereby achieving noise cancellation within the target space 176, particularly in the area near the error microphone 171.

[0139] For example, the NC filter is a filter that adds a characteristic to reduce the noise observed at the position of the error microphone 171. Therefore, if sound is output based on the cancellation signal obtained by filtering with the NC filter, the noise (load noise) observed at the position of the error microphone 171 will be canceled out by the sound based on the cancellation signal.

[0140] The acoustic metamaterial 175 is a sound absorber designed by the design process shown in Figure 3, with the position of the error microphone 171 as the evaluation point, and manufactured by the manufacturing process shown in Figure 5. In the design of the acoustic metamaterial 175, the positions of the error microphone 171 and the speaker 174 correspond to the positions of the evaluation point and the sound source in the design process described with reference to Figure 3.

[0141] In the example shown in Figure 7, the acoustic metamaterial 175 is installed on the ceiling of the target space 176, which is the vehicle compartment. The installation surface and number of acoustic metamaterials 175 installed in the target space 176 can be any number or surface.

[0142] In the example shown in Figure 7, noise cancellation can be performed with higher precision by installing the acoustic metamaterial 175 on the surface (ceiling) that forms the target space 176.

[0143] Specifically, for example, when performing noise cancellation using speaker 174, the sound field can be adjusted (controlled) by installing acoustic metamaterial 175 so that dips or other issues do not occur in the sound transmission characteristics from speaker 174 to error microphone 171.

[0144] In noise cancellation (NC), an NC filter is generated that targets a response in which the inverse characteristics of the sound transmission characteristics from the NC speaker 174 to the error microphone 171 are convolved with the noise characteristics observed by the error microphone 171 installed in the target space 176 that is the target of NC.

[0145] In other words, as shown in Figure 8, for example, an NC filter is generated that corresponds to the transmission characteristics from speaker 174 to error microphone 171. Note that in Figure 8, the same reference numerals are used for parts corresponding to those in Figure 7, and their explanations are omitted as appropriate.

[0146] For example, as shown on the left side of the figure, when the acoustic metamaterial 175 is not installed in the target space 176, the transmission characteristics from the speaker 174 to the error microphone 171 are as shown by arrow Q11.

[0147] In the section indicated by arrow Q11, the horizontal axis represents frequency, and the vertical axis represents the gain at each frequency, indicating the transfer characteristics. Curve L11 shows the transfer characteristics from speaker 174 to error microphone 171.

[0148] In this example, it can be seen that a dip (notch) that is convex downwards in the figure occurs in a certain frequency portion of the transfer characteristic shown by curve L11. Such a dip is caused, for example, by the interference between the primary sound propagating from speaker 174 to error microphone 171 and the reflected sound. In other words, the dip in the transfer characteristic is caused by the shape of the target space 176 and the complex acoustic impedance of the surfaces forming the target space 176.

[0149] Thus, when the transmission characteristics include dips (notches) caused by the interference between the primary sound and the reflected sound, the phase characteristics of the NC filter will include a steep response, which is known to reduce the accuracy of the NC.

[0150] Therefore, as shown on the right side of the figure, by installing an acoustic metamaterial 175 in the target space 176, it is conceivable to adjust the phase of the sound reflection surface, that is, the surface forming the target space 176, so that a dip does not occur in the transmission characteristics in the frequency band targeted by the NC. By performing such phase adjustment, the characteristics of the NC can be improved, that is, a more accurate NC can be realized.

[0151] In this case, the acoustic metamaterial 175 is designed and manufactured so that, for example, the transfer characteristics shown by arrow Q12 are obtained. In the section shown by arrow Q12, the horizontal axis represents frequency, and the vertical axis represents the gain at each frequency that shows the transfer characteristics. Curve L12 shows the transfer characteristics from speaker 174 to error microphone 171 when the acoustic metamaterial 175 is installed in the target space 176.

[0152] For example, when designing the acoustic metamaterial 175, the position of the speaker 174 is set as the sound source position to generate a 3D acoustic analysis model, and the position of the error microphone 171 is set as the evaluation point position. Then, the sound pressure frequency characteristics corresponding to the transfer characteristics shown in curve L12 are set as the target sound pressure frequency characteristics, and the design process described with reference to Figure 3 is performed to identify the shape parameters of the acoustic metamaterial 175.

[0153] When the acoustic metamaterial 175 obtained in this way is placed in the target space 176, the acoustic metamaterial 175 controls the sound field of the target space 176, that is, the sound pressure frequency characteristics at the position of the error microphone 171. As a result, the transfer characteristics shown in curve L12 are obtained, and the dips that occur in the transfer characteristics are eliminated, so an NC filter that can reduce noise with higher precision is obtained.

[0154] In the examples shown in Figures 7 and 8 above, the transmission characteristics from speaker 174 to error microphone 171 in the NC feedback loop include the characteristics of the sound field of the target space 176. By installing the acoustic metamaterial 175, the sound field of the target space 176, i.e., the sound pressure frequency characteristics in the error microphone 171, can be adjusted to the desired characteristics, thereby eliminating peculiar characteristics such as sharp dips from the feedback loop. In other words, it is possible to prevent dips from occurring in the sound pressure frequency characteristics of the sound picked up by the error microphone 171 at each timing. This makes it possible to improve the accuracy of feedback control in the adaptive process of performing NC while updating the NC filter. In other words, it is possible to achieve higher accuracy NC.

[0155] <Application Example 3> As a third example, we will explain another application example of NC technology using a speaker.

[0156] This example involves installing acoustic metamaterials (sound absorbers) designed using the design process shown in Figure 3 and manufactured using the manufacturing process shown in Figure 5, across the entire floor or ceiling of the room in question.

[0157] By installing acoustic metamaterial across the entire floor or ceiling of a room, the antinodes and nodes of standing modes can be shifted to avoid a wide range of areas at the height of a typical person's head. In other words, an appropriate sound field can be achieved for a wider area that includes the region where a typical person's head is located. In this case, the target space is not limited to a closed space, but can be any type of space.

[0158] As a concrete example, consider an environment like a movie theater, where multiple seating areas are arranged in a space with different levels for each area, and sound is emitted from speakers towards the seating areas.

[0159] In target spaces such as movie theaters, interference between sound from speakers and sound emitted from speakers and reflected from the floor can cause dips in the sound pressure frequency characteristics at the audience seating positions. In this case, it is expected that dips will occur at similar frequencies at all seats.

[0160] Therefore, it is conceivable to install acoustic metamaterials on the floor surface of the target space and control the reflection phase angle of the floor surface. By doing so, the spatial location where a dip occurs at a specific frequency in the sound pressure frequency characteristics can be moved to a position above the head position of the people sitting in the seats, or to the chest position of the people sitting in the seats.

[0161] In the above explanation, we have primarily described sound-absorbing materials as acoustic metamaterials. However, this technology is not limited to these; it can be applied to any sound-absorbing material that utilizes a resonator (resonance system) or a resonating chamber (resonance system).

[0162] For example, acoustic metamaterials used as sound absorbers are not limited to those that utilize Helmholtz resonance; similar effects can be obtained with acoustic metamaterials that use resonance systems such as membrane vibration or air column resonance.

[0163] Furthermore, the above describes an example of modeling the complex acoustic impedance of an acoustic metamaterial using a series equivalent circuit of RLC in order to identify the shape parameters of the sound absorber (acoustic metamaterial). However, the method is not limited to this; any method of identifying the shape parameters is acceptable as long as it ultimately yields shape parameters that take into account the complex acoustic impedance, especially the reflection phase angle.

[0164] For example, instead of using model parameters derived from a series equivalent circuit of an RLC, the shape parameters of the acoustic metamaterial may be directly identified in the optimization calculation of a 3D acoustic simulation using the shape parameters of the acoustic metamaterial as design variables.

[0165] In such cases, for example, the acoustic analysis model generation unit 81 generates a 3D acoustic analysis model consisting of information indicating the three-dimensional shape and size of the target space, shape parameters of the acoustic metamaterial installed on the installation surface, and complex acoustic impedances of surfaces other than the installation surface of the target space (surfaces where the acoustic metamaterial is not installed). The sound pressure frequency characteristics of any position (point) can also be obtained by frequency response analysis based on this 3D acoustic analysis model.

[0166] In the shape identification unit 85, an optimization calculation is performed using the squared error between the applicable sound pressure frequency characteristics obtained by frequency response analysis based on a 3D acoustic analysis model with predetermined shape parameters and the target sound pressure frequency characteristics as the objective function, and the shape parameters as design variables. Through this optimization calculation, shape parameters are identified such that the sound pressure frequency characteristics at the evaluation point become the target sound pressure frequency characteristics.

[0167] Alternatively, the complex acoustic impedance of the acoustic metamaterial may not be modeled, and the 3D acoustic analysis model generated in step S11 of Figure 3 may be used as is to identify the complex acoustic impedance (sound absorption coefficient and reflection phase angle).

[0168] In such cases, in the design process shown in Figure 3, the process in step S16 is not performed. Instead, in step S17, the parameter identification unit 83 performs optimization using the squared error between the applied sound pressure frequency characteristics and the target sound pressure frequency characteristics as the objective function, and the complex acoustic impedance itself as the design variable. Then, the shape identification unit 85 identifies the shape parameters of the acoustic metamaterial based on the complex acoustic impedance identified by the parameter identification unit 83.

[0169] <Description of a computer to which this technology is applied> The series of processes described above can be executed by hardware or by software. When the series of processes are executed by software, the programs that make up the software are installed on the computer. Here, the term "computer" includes computers built into dedicated hardware, as well as general-purpose personal computers, for example, that can perform various functions by installing various programs.

[0170] Figure 9 is a block diagram showing an example of the hardware configuration of a computer that executes the series of processes described above using a program.

[0171] In a computer, the processing circuit 901, ROM (Read Only Memory) 902, and RAM (Random Access Memory) 903 are interconnected by a bus 904.

[0172] An input / output interface 905 is further connected to the bus 904. An input / output interface 905 is connected to an input unit 906, an output unit 907, a recording unit 908, a communication unit 909, and a drive 910.

[0173] The input unit 906 may include physical or virtual means of operation that the user operates to input information, such as a keyboard, mouse, or touch panel, as well as means of inputting information by the user through voice, eye gaze, etc. Furthermore, the input unit 906 may include sensors for inputting various physical quantities to the computer.

[0174] For example, the input unit 906 may include sensors that acquire physical quantities such as light (including infrared light other than visible light) and sound, such as cameras and microphones. Alternatively, the input unit 906 may include sensors that acquire other physical quantities such as temperature, moisture content, acceleration, and distance.

[0175] The output unit 907 may include means for presenting information to the user by stimulating the user's senses, such as a display, speaker, or haptic device. The recording unit 908 consists of a hard disk, non-volatile or volatile memory, etc., and records various types of information (including programs).

[0176] The communication unit 909 is a network interface, etc., and performs wired or wireless communication with the outside. The drive 910 drives removable media 911 such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory.

[0177] The processing circuit 901 includes a processor that executes programs such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor). The processing circuit 901 (its processor) loads the program recorded in the recording unit 908 into the RAM 903 via the input / output interface 905 and the bus 904, and executes it, thereby performing the series of processes described above.

[0178] The processing circuit 901 can output the processing results of a series of processes from the output unit 907, for example, via the bus 904 and the input / output interface 905, as needed. The processing circuit 901 can also record the processing results in the recording unit 908 or transmit them from the communication unit 909.

[0179] The program executed by the computer (processing circuit 901) can be provided by recording it on a removable medium 911, such as a package medium. The program can also be provided via wired or wireless transmission media, such as a local area network, the internet, or digital satellite broadcasting.

[0180] In a computer, a program can be installed in the recording unit 908 via the input / output interface 905 by inserting the removable media 911 into the drive 910. Alternatively, a program can be received by the communication unit 909 from another device, such as a server, via a wired or wireless transmission medium, and installed in the recording unit 908. Furthermore, programs can be pre-installed in the ROM 902 or the recording unit 908.

[0181] The programs executed by the computer may be programs that are processed chronologically in the order described herein, or they may be programs that are processed in parallel or at necessary times, such as when a call is made.

[0182] The processes that a computer performs according to a program do not necessarily have to follow the order described in the flowchart. In other words, the processes that a computer performs according to a program include processes that are executed in parallel or individually (e.g., parallel processing and object-based processing).

[0183] The program may be processed by a single computer (processor), or it may be processed in a distributed manner by multiple computers. Furthermore, the program may be transferred to a remote computer and executed there.

[0184] When the computer executes the program and the above-described series of processes are performed, the input unit 906 functions as the input unit 71 in Figure 2 and the error microphone 171 and sensor unit 172 in Figure 7, and the output unit 907 functions as the display unit 72 in Figure 2 and the speaker 174 in Figure 7. Furthermore, the processing circuit 901 functions as the acoustic analysis model generation unit 81 to the shape identification unit 85 in Figure 2 when the program is executed. In addition, the processing circuit 901 functions as the control unit 173 in Figure 7.

[0185] In this specification, a system means one component or a collection of multiple components (devices, modules (parts), etc.). Therefore, one or more components of a computer, for example, only the processor, or a combination of the processor and memory (for example, only the processing circuit 901, or a combination of the processing circuit 901 to the bus 904, etc.), constitute a system. Regarding a collection of multiple components, it is not necessary whether all components reside in the same enclosure. Therefore, multiple devices housed in separate enclosures and connected via a network, or a single device containing multiple modules within a single enclosure, are all systems. Furthermore, for example, the entire computer, or a combination of a computer and other devices such as a server (not shown), also constitute a system.

[0186] The components (blocks) of the apparatus illustrated in this specification are functional conceptual blocks, and the actual apparatus does not need to have the illustrated configuration. That is, the apparatus can have any configuration in which the functions of the illustrated components are divided into any units and / or integrated, for example, a configuration having one block in which the functions of all components are integrated.

[0187] Furthermore, the embodiments of this technology are not limited to those described above, and various modifications are possible without departing from the spirit of this technology.

[0188] For example, this technology can be configured as cloud computing, where a single function is shared and processed collaboratively by multiple devices via a network.

[0189] Furthermore, each step described in the flowchart above can be performed by a single device, or it can be divided and performed by multiple devices.

[0190] Furthermore, if a single step includes multiple processes, those processes can be executed by a single device or shared among multiple devices.

[0191] Furthermore, this technology can also be configured as follows:

[0192] (1) An information processing method comprising: (1) an information processing device identifying parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator, which is installed on a surface forming the target space, based on a target sound pressure frequency characteristic at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristic at an arbitrary point in the target space; and identifying the shape of the sound absorber based on the parameters. (2) The information processing method according to (1), wherein the acoustic analysis model comprises at least information relating to the shape of the target space and information relating to the complex acoustic impedance of the surface forming the target space. (3) The information processing method according to (1) or (2), wherein the sound absorber is an acoustic metamaterial. (4) The information processing method according to any one of (1) to (3), wherein the parameters are sound absorption coefficient and reflection phase angle. (5) The information processing method according to any one of (1) to (3), wherein the parameters are resistance, inductance, and capacitance when the complex acoustic impedance is modeled in a series equivalent circuit. (6) The information processing method according to (5), wherein the shape of the sound absorber is identified based on a theoretical model for calculating the parameters from the shape of the sound absorber and the parameters identified based on the target sound pressure frequency characteristics and the acoustic analysis model. (7) The information processing method according to any one of (1) to (6), further comprising determining the target sound pressure frequency characteristics. (8) The information processing method according to (7), further comprising displaying the sound pressure frequency characteristics of the evaluation point when the sound absorber is not installed in the target space, and determining the target sound pressure frequency characteristics in response to user input. (9) The information processing method according to any one of (1) to (8), further comprising generating the acoustic analysis model based on the shape of the target space and the complex acoustic impedance of each surface forming the target space.(10) The information processing method according to (3), wherein the shape of the sound absorber is at least one of the following: the arrangement of a plurality of cells constituting the acoustic metamaterial, the arrangement of a plurality of resonators or resonators constituting the cells, the combination of resonators or resonators of different types constituting the cells, the length of the neck of the resonator, the cross-sectional area of ​​the neck, and the dimensions of the cavity of the resonator. (11) The information processing method according to any one of (1) to (10), wherein the shape of each of the plurality of sound absorbers installed in the target space is identified. (12) The information processing method according to any one of (1) to (11), wherein the target space is a closed space. (13) An information processing method according to any one of (1) to (12), wherein the parameters of the sound absorber are identified by performing optimization with the squared error between the target sound pressure frequency characteristics and the sound pressure frequency characteristics of the evaluation point obtained based on the acoustic analysis model when the sound absorber with predetermined parameters is installed on a predetermined surface of the target space, the objective function of optimization. (14) An information processing device comprising: a parameter identification unit that identifies parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator installed on a surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics of an arbitrary point in the target space; and a shape identification unit that identifies the shape of the sound absorber based on the parameters. (15) A program that causes a computer to perform a process that includes identifying parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator, which is installed on the surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics at any point in the target space, and identifying the shape of the sound absorber based on the parameters.(16) A noise-canceling system comprising: a microphone placed in a target space to pick up ambient sounds; a sensor to detect noise; a speaker that outputs a sound to cancel the noise observed at the position of the microphone based on a cancellation signal generated based on the sound pickup signal obtained by the microphone and the sensor signal obtained by the sensor; and a sound-absorbing body using a resonator or resonator installed on the surface forming the target space, wherein the sound-absorbing body has a shape identified based on parameters relating to the complex acoustic impedance of the sound-absorbing body, which are parameters identified based on the target sound pressure frequency characteristics at the position of the microphone and an acoustic analysis model for obtaining the sound pressure frequency characteristics at any point in the target space. (17) A method for manufacturing a sound absorber using a resonator or resonator, wherein the sound absorber having the shape is produced based on a shape parameter indicating the shape of the sound absorber, which is identified based on a parameter relating to the complex acoustic impedance of the sound absorber installed on a surface forming the target space, and which is a parameter identified based on a target sound pressure frequency characteristic at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristic at any point in the target space, and which is installed on a surface forming the target space. (18) An information processing device that includes identifying a shape parameter indicating the shape of a sound absorber using a resonator or resonator installed on a surface forming the target space, based on a target sound pressure frequency characteristic at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristic at any point in the target space, wherein the acoustic analysis model comprises at least information relating to the shape of the target space, the shape parameter of the sound absorber installed on a surface forming the target space, and the complex acoustic impedance of a surface forming the target space on which the sound absorber is not installed.

[0193] 11 Target space, 21-1, 21-2, 21 Acoustic metamaterial, 61 Information processing device, 71 Input unit, 72 Display unit, 74 Control unit, 81 Acoustic analysis model generation unit, 82 Analysis processing unit, 83 Parameter identification unit, 84 Theoretical model generation unit, 85 Shape identification unit, 161 Noise canceling system, 171 Error microphone, 173 Control unit, 174 Speaker, 175 Acoustic metamaterial

Claims

1. An information processing method comprising: an information processing device identifying parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator, which is installed on a surface forming the target space, based on a target sound pressure frequency characteristic at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristic at an arbitrary point in the target space; and identifying the shape of the sound absorber based on the parameters.

2. The information processing method according to claim 1, wherein the acoustic analysis model comprises at least information relating to the shape of the target space and information relating to the complex acoustic impedance of the surfaces forming the target space.

3. The information processing method according to claim 1, wherein the sound-absorbing material is an acoustic metamaterial.

4. The information processing method according to claim 1, wherein the parameters are sound absorption coefficient and reflection phase angle.

5. The information processing method according to claim 1, wherein the parameters are the resistance, inductance, and capacitance when the complex acoustic impedance is modeled in a series equivalent circuit.

6. The information processing method according to claim 5, which identifies the shape of a sound absorber based on a theoretical model for calculating the parameters from the shape of the sound absorber, and the parameters identified based on the target sound pressure frequency characteristics and the acoustic analysis model.

7. The information processing method according to claim 1, further comprising determining the target sound pressure frequency characteristics.

8. The information processing method according to claim 7, further comprising displaying the sound pressure frequency characteristics of the evaluation point when the sound absorber is not installed in the target space, and determining the target sound pressure frequency characteristics in response to user input.

9. The information processing method according to claim 1, further comprising generating the acoustic analysis model based on the shape of the target space and the complex acoustic impedance of each surface forming the target space.

10. The information processing method according to claim 3, wherein the shape of the sound absorber is at least one of the following: the arrangement of a plurality of cells constituting the acoustic metamaterial, the arrangement of a plurality of resonators or resonators constituting the cells, the combination of resonators or resonators of different types constituting the cells, the length of the neck of the resonator, the cross-sectional area of ​​the neck, and the dimensions of the cavity of the resonator.

11. The information processing method according to claim 1, wherein the shape of each of the multiple sound-absorbing bodies installed in the target space is identified.

12. The information processing method according to claim 1, wherein the target space is a closed space.

13. The information processing method according to claim 1, wherein the parameters of the sound absorber are identified by performing optimization with the squared error between the target sound pressure frequency characteristics and the sound pressure frequency characteristics of the evaluation point obtained based on the acoustic analysis model, when the sound absorber having predetermined parameters is installed on a predetermined surface of the target space, and the objective function is the squared error between the target sound pressure frequency characteristics and the sound pressure frequency characteristics of the evaluation point obtained based on the acoustic analysis model.

14. An information processing device comprising: a parameter identification unit that identifies parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator installed on the surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics at an arbitrary point in the target space; and a shape identification unit that identifies the shape of the sound absorber based on the parameters.

15. A program that causes a computer to perform a process including identifying parameters relating to the complex acoustic impedance of a sound absorber using a resonator or resonator, which is installed on the surface forming the target space, based on the target sound pressure frequency characteristics at an evaluation point in the target space and an acoustic analysis model for obtaining the sound pressure frequency characteristics at any point in the target space, and identifying the shape of the sound absorber based on the parameters.

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