Sound radiation control structure and design support method thereof

Abstract

To easily and efficiently reduce sound radiation from a sound radiation control structure and to improve a design freedom degree of the sound radiation control structure.SOLUTION: The present invention relates to a sound radiation control structure, and the sound radiation control structure includes first cells 11 and 21 and second cells 12 and 22, which have a specified natural vibration or acoustic mode. Resonance frequencies f11 and f12 of the specified natural vibration mode in the first and second cells or resonant frequencies f21 and f22 of the specified natural acoustic mode differ from each other, the first and second cells are arranged so as to be adjacent to each other, and radiation elements 11a and 21a of the first cell and radiation elements 12a and 22a of the second cell are arranged at intervals so as to excite air in a radiation space R independently and in anti-phase with each other to create interference between resonance or resonant frequencies of the first and second cells to reduce sound radiation. The present invention also relates to a design support method of the sound radiation control structure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sound radiation control structure configured to be able to radiate sound based on an input sound and to be able to control the radiated sound. The present invention relates to a design support method used for designing a sound radiation control structure capable of radiating sound based on an input sound and to be able to control the radiated sound. [Background technology]

[0002] When sound is input to a structure, the sound is radiated from the structure based on the input sound (input sound). When the sound radiated from the structure in this way (radiated sound) becomes loud, it may be recognized as an unpleasant noise. For this reason, in the field of acoustics, various technologies (radiated sound reduction technologies) have been proposed to reduce such radiated sound.

[0003] A first example of a technology for reducing radiated sound is a soundproof panel that has a plurality of divided regions that generate a plurality of primary vibration modes at the same resonance frequency, and is configured so that the primary vibration modes generated in adjacent regions among the plurality of regions are in opposite phase to each other. This soundproof panel is divided into a plurality of regions by a reinforcing material attached to the surface thereof so as to generate a plurality of primary vibration modes. (See, for example, Patent Document 1, particularly paragraphs

[0041] to

[0043] of Patent Document 1.)

[0004] A second example of a technology for reducing radiated sound is an acoustic structure that includes a reflector having a plurality of sound-transmitting regions that transmit sound waves, and a reflecting region adjacent to the sound-transmitting region that radiates a reflected wave in response to the incident sound wave, and a sound wave radiating means that radiates to the external space via the sound-transmitting region a sound wave such that, when the reflecting region radiates a reflected wave into the external space in response to a sound wave incident on the reflector from the external space, the phase in the sound-transmitting region is different from the phase of the reflected wave in the reflecting region, and the real part of the value obtained by dividing the specific acoustic impedance in the sound-transmitting region by the characteristic impedance of the medium of the sound-transmitting region is approximately 0 (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-076523 A [Patent Document 2] JP 2014-240975 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when multiple regions are divided by a reinforcing material attached to the surface of the soundproof panel as in the soundproof panel in the first example of the radiated sound reduction technology, it is extremely difficult to intentionally make the primary vibration modes occurring in adjacent regions out of the multiple regions opposite in phase to each other. In other words, the reality is that we have no choice but to hope that the primary vibration modes occurring in adjacent regions will happen to be opposite in phase to each other by chance. Therefore, in the first example of the radiated sound reduction technology, it is extremely difficult to manufacture a soundproof panel that effectively reduces radiated sound. And the structure of the soundproof panel for generating multiple primary vibration modes so that adjacent primary vibration modes are opposite in phase to each other is limited, and the degree of freedom in design is low.

[0007] Furthermore, it is difficult to radiate sound waves, which are determined so that the phase in the sound-transmitting region is different from the phase in the reflection region of the reflected wave and the real part of the value obtained by dividing the specific acoustic impedance in the sound-transmitting region by the characteristic impedance of the medium in the sound-transmitting region is approximately 0, to the external space through the sound-transmitting region, as in the acoustic structure in the second example of the radiated sound reduction technology. Therefore, it is also difficult to manufacture an acoustic structure that effectively reduces radiated sound. Furthermore, the structure of the acoustic structure for generating such sound waves is limited, and the degree of freedom in design is low.

[0008] In view of the above circumstances, it is desirable to provide a sound radiating control structure that can easily and efficiently reduce sound radiation and improve design freedom. It is also desirable to provide a design support method for a sound radiating control structure that can easily manufacture the sound radiating control structure with a high degree of design freedom and efficiently reduce sound radiated from the manufactured sound radiating control structure. [Means for solving the problem]

[0009] In order to solve the above problem, one embodiment of a sound radiating control structure is a sound radiating control structure configured to radiate sound toward a predetermined radiation space based on an input sound and to control the radiated sound, the sound radiating control structure comprising a first cell and a second cell having a specific natural mode which is a specific natural vibration mode or a specific natural acoustic mode, the resonant frequencies of the specific natural vibration mode or the specific frequency which is the resonant frequency of the specific natural acoustic mode in the first and second cells are different from each other, the first and second cells each have a radiating element facing the radiation space, the first and second cells are installed adjacent to each other, and the radiating elements of the first and second cells are arranged at intervals so as to excite the air in the radiation space independently of each other and in opposite phase to each other, so as to generate an interference effect between the specific frequencies of the first and second cells to reduce the radiated sound.

[0010] According to such a sound radiating control structure, the constraints of arranging the first and second cells adjacent to each other with a gap between them so that the radiation elements of the first and second cells can excite the air in the radiation space independently of each other, and the constraints of arranging the first and second cells adjacent to each other with a gap between them, are less restrictive than those of conventional structures, and therefore the design freedom of the sound radiating control structure can be improved.

[0011] In addition, in the first and second cells having a structure based on the above constraints, the interference between these specific frequencies can easily and efficiently reduce the radiated sound from the radiated sound control structure. Therefore, the radiated sound can be easily and efficiently reduced and the design freedom can be improved.

[0012] In one embodiment of the sound radiating control structure, the maximum separation distance between the radiating elements of the first and second cells is equal to or less than a wavelength calculated based on one of the specific frequencies of the first and second cells.

[0013] According to such a sound radiating control structure, under the condition of the maximum separation distance, interference between the specific frequencies can be efficiently generated, and the sound radiated can be efficiently reduced.

[0014] In one embodiment of a radiated sound control structure, assuming the existence of a first virtual structure having a number of the first cells and b number of the second cells, in which the radiated sound control structure is modified to have b number of the first cells instead of b number of the second cells, and a second virtual structure in which the radiated sound control structure is modified to have a number of the second cells instead of a number of the first cells, where a and b are each an integer greater than or equal to 1, the first and second cells are configured such that, at a predetermined intermediate frequency between these specific frequencies, a value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space excited by the first virtual structure by a is substantially equal to a value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space excited by the second virtual structure by b, in order to generate the interference effect so as to most reduce the radiated sound at the predetermined intermediate frequency between these specific frequencies.

[0015] According to such a sound radiating control structure, it is possible to efficiently reduce the sound radiated at intermediate frequencies between the specific frequencies. In particular, when it is desired to reduce the sound radiated at a desired frequency, it is sufficient to make the desired frequency approximately coincident with the intermediate frequency. Therefore, it is possible to easily and efficiently reduce the sound radiated.

[0016] In one embodiment of the sound radiating control structure, the first and second cells have the same order of a specific eigenmode.

[0017] According to such a sound radiating control structure, when the order of a specific eigenmode of the first and second cells is the same, particularly when the order of the specific eigenmode of the first and second cells is first order, interference occurs efficiently between these specific frequencies, making it possible to efficiently reduce sound radiated from the sound radiating control structure.

[0018] In one embodiment of the sound radiating control structure, the specific natural mode is the specific natural vibration mode, the specific frequency is the resonant frequency of the specific natural vibration mode, the first cell and the second cell are first vibrating bodies and second vibrating bodies, respectively, having a radiation surface portion facing the radiation space, and the radiation element is the radiation surface portion.

[0019] According to such a sound radiating control structure, the first and second vibrators are configured to generate specific natural vibration modes at different resonant frequencies, and the first and second vibrators are arranged adjacent to each other with a gap between them so that the radiation surfaces of the first and second vibrators can excite the air in the radiation space independently of each other. This restriction places a smaller restriction on the structure than the conventional structure, and therefore the design freedom of the sound radiating control structure can be improved.

[0020] Furthermore, in the first and second vibrators having a structure based on the above constraints, the interference action at these resonant frequencies makes it possible to easily and efficiently reduce the radiated sound from the sound radiating control structure. Therefore, it is possible to easily and efficiently reduce the radiated sound and improve the design freedom.

[0021] In one embodiment of the sound radiation control structure, the specific natural mode is the specific natural acoustic mode, the specific frequency is the resonant frequency of the specific natural acoustic mode, the first cell and the second cell are first resonators and second resonators, respectively, having an opening that opens toward the radiation space, and the radiation element is the opening.

[0022] According to such a sound radiating control structure, the constraints of configuring the first and second resonators to generate specific natural acoustic modes at different resonant frequencies and arranging the first and second resonators adjacent to each other with a gap between the openings of the first and second resonators so that the openings can excite the air in the radiation space independently of each other, are less restrictive in structure compared to conventional structures, and therefore the design freedom of the sound radiating control structure can be improved.

[0023] Furthermore, in the first and second resonators having a structure based on the above constraints, the interference action at these resonant frequencies makes it possible to easily and efficiently reduce the radiated sound from the sound radiating control structure. Therefore, the radiated sound can be easily and efficiently reduced and the degree of freedom in design can be improved.

[0024] A design support method for a radiated sound control structure according to one embodiment is a design support method for a radiated sound control structure used to design a radiated sound control structure that is capable of radiating radiated sound toward a predetermined radiation space based on an input sound and is capable of controlling the radiated sound, the design support method including a design support step of provisionally determining a configuration of a first cell and a second cell having a specific natural mode which is a specific natural vibration mode or a specific natural acoustic mode, and determining an arrangement of the first and second cells adjacent to each other, wherein each of the first and second cells has a radiating element facing the radiation space, the resonant frequency of the specific natural vibration mode or the specific frequency which is the resonant frequency of the specific natural acoustic mode in the first and second cells is different from each other, and the radiating elements of the first and second cells are arranged at an interval, and the design support step includes adjusting the provisionally determined configurations of the first and second cells so that the radiating elements of the first and second cells are capable of exciting the air in the radiation space independently of each other and in opposite phase to each other, so as to generate an interference effect between the specific frequencies of the first and second cells so as to reduce the radiated sound.

[0025] According to such a design support method for a sound radiating control structure, the constraints of configuring the first and second cells to generate specific eigenmodes at different specific frequencies and arranging the first and second cells adjacent to each other with a gap between them so that the radiation elements of the first and second cells can excite the air in the radiation space independently of each other are less restrictive than conventional structures, and therefore the sound radiating control structure can be designed with a high degree of freedom.

[0026] Furthermore, in the first and second cells having a structure based on the above constraints, the interference between these specific frequencies can easily and efficiently reduce the sound radiated from the sound radiating control structure. Therefore, the sound radiating control structure can be manufactured easily and with a high degree of design freedom, and the sound radiated from the manufactured sound radiating control structure can be efficiently reduced.

[0027] In one embodiment of a design support method for a radiated sound control structure, in the design support step, when a and b are each an integer greater than or equal to 1, assuming the existence of a first virtual structure in which the radiated sound control structure has a number of the first cells and b number of the second cells, and in which the radiated sound control structure is modified to have b number of the first cells instead of b number of the second cells, and a second virtual structure in which the radiated sound control structure is modified to have a number of the second cells instead of a number of the first cells, at least one of the shape, size, density, elastic modulus, and material of each of the provisionally determined first and second cells is adjusted so that a value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space excited by the first virtual structure by a is substantially equal to a value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space excited by the second virtual structure by b at the intermediate frequency, in order to generate the interference effect so as to most reduce the radiated sound at a predetermined intermediate frequency between specific frequencies of the first and second cells.

[0028] According to such a design support method for a radiated sound control structure, it is possible to efficiently reduce radiated sound at intermediate frequencies between the specific frequencies. In particular, when it is desired to reduce radiated sound at a desired frequency, it is sufficient to roughly match this desired frequency with the intermediate frequency. Therefore, it is possible to easily and efficiently reduce radiated sound. Effect of the Invention

[0029] According to the sound radiating control structure of one embodiment, it is possible to easily and efficiently reduce sound radiated therefrom and to improve design freedom. According to the design support method for a sound radiating control structure of one embodiment, it is possible to easily manufacture a sound radiating control structure with a high degree of design freedom and to efficiently reduce sound radiated from the manufactured sound radiating control structure. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a plan view illustrating a schematic view of a radiated sound control structure according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line W1-W1 in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line W2-W2 in FIG. [Figure 4] FIG. 4 is a graph showing the relationship between the frequency in the sound radiating control structure, the first virtual structure, and the second virtual structure relating to the first embodiment and Example 1, respectively, and the value obtained by multiplying the weighted value of the average vibration volume velocity in the air in the radiation space excited by these, and the transmission loss. [Diagram 5] FIG. 5 is a plan view illustrating a schematic view of a radiated sound control structure according to the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along line W3-W3 in FIG. [Figure 7] 7 is a cross-sectional view taken along line W4-W4 in FIG. [Figure 8] FIG. 8 is a graph showing the relationship between the frequency in the radiated sound control structure, the first virtual structure, and the second virtual structure relating to the second embodiment and Example 2, respectively, and the value obtained by multiplying the weighted value by the magnitude of the average vibration volume velocity in the air in the radiation space excited by these, and the transmission loss. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The sound radiating control structures according to the first and second embodiments and the design support methods thereof are described below. The sound radiating control structures according to the respective embodiments are configured to be capable of radiating sound toward a predetermined radiation space based on an input sound, and to be capable of controlling the radiated sound.

[0032] Furthermore, the radiated sound control structure of each embodiment comprises a first cell and a second cell having a specific natural mode, and the specific frequencies which are the resonant frequencies of the specific natural vibration modes or the resonant frequencies of the specific natural acoustic modes in the first and second cells are different from each other, and each of the first and second cells has a radiating element facing the radiation space, the first and second cells are arranged adjacent to each other, and the radiating elements of the first and second cells are arranged at intervals so as to be able to excite the air in the radiation space independently of each other and in opposite phase to each other, so as to generate an interference effect between the specific frequencies of the first and second cells to reduce the radiated sound.

[0033] In the sound radiating control structure of the first embodiment, the specific natural mode is a specific natural vibration mode, the specific frequency is a resonant frequency of the specific natural vibration mode, the first cell and the second cell are a first vibrating body and a second vibrating body, respectively, having a radiation surface portion facing the radiation space, and the radiation element is the radiation surface portion.

[0034] In the sound radiation control structure of the second embodiment, the specific natural mode is a specific natural acoustic mode, the specific frequency is a resonant frequency of the specific natural acoustic mode, the first cell and the second cell are first resonators and second resonators, respectively, having openings opening toward the radiation space, and the radiation element is the opening.

[0035] "First embodiment" A sound radiating control structure and a design support method thereof according to a first embodiment will be described.

[0036] "Outline of sound radiation control structure" 1 to 4, the radiated sound control structure according to this embodiment is generally configured as follows: The radiated sound control structure is configured to be able to radiate radiated sound toward a predetermined radiation space R based on an input sound, and to be able to control the radiated sound.

[0037] In FIG. 4, the horizontal axis f indicates frequency (Hz), and the vertical axis V on the left side of the page indicates the value obtained by multiplying the magnitude of the average vibration volume velocity by a weight (m 3 4, the vertical axis C1 indicates the frequency and the transmission loss in the radiation control structure, the dashed line D1 indicates the frequency and the value obtained by multiplying the magnitude of the average vibration volume velocity by a weight in a first hypothetical structure described later, and the dashed line E1 indicates the frequency and the value obtained by multiplying the magnitude of the average vibration volume velocity by a weight in a second hypothetical structure described later.

[0038] As shown in Figures 1 to 3, the sound radiating control structure has a first vibrating body 11 and a second vibrating body 12. In Figures 1 to 3, the second vibrating body 12 is shown using cross-hatching. With reference to Figures 1 to 4, each of the first and second vibrating bodies 11 and 12 has a specific natural vibration mode. The resonant frequency f of the specific natural vibration mode in the first and second vibrating bodies 11 and 12 is 11 ,f 12 The first and second vibrating bodies 11 and 12 have radiation surface portions 11a and 12a facing the radiation space R, respectively.

[0039] The first and second vibrating bodies 11 and 12 are arranged adjacent to each other. The radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 are arranged to have a resonance frequency f 11 ,f 12 They are spaced apart so as to be able to excite the air in the radiation space R independently of each other and in opposite phase to each other, so as to produce an interference effect between them to reduce radiated sound.

[0040] Further, the sound radiating control structure according to this embodiment can be roughly constructed as follows. With reference to Figs. 1 and 4, the maximum separation distance h1 between the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 is set to a value smaller than the resonant frequency f 11 ,f 12The wavelength λ is calculated based on either 11 ,λ 12 It can be as follows:

[0041] The sound radiating control structure has a1 first vibrating bodies 11 and b1 second vibrating bodies 12, where a1 and b1 are each an integer equal to or greater than 1. Note that, in Figs. 1 to 3, as an example, a sound radiating control structure having 13 first vibrating bodies 11 and 12 second vibrating bodies 12 is shown. In this case, a1 is 13 and b1 is 12. However, the numbers of the first and second vibrating bodies are not limited to this.

[0042] Here, it is assumed that there exists a first imaginary structure in which the sound radiating control structure is modified so that b1 first vibrators 11 are installed instead of b1 second vibrators 12, and a second imaginary structure in which the sound radiating control structure is modified so that a1 second vibrators 12 are installed instead of a1 first vibrators 11. In this case, the first and second vibrators 11 and 12 have their resonant frequencies f 11 ,f 12 A given intermediate frequency f 11-12 In order to generate interference that minimizes the radiated sound at intermediate frequency f 11-12 The value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a1 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b1.

[0043] Furthermore, the orders of the specific natural vibration modes of the first and second vibrating bodies 11 and 12 may be the same. For example, such an order may be the first order. However, the orders of the specific natural vibration modes of the first and second vibrating bodies may be different.

[0044] "Details of sound radiation control structure" 1 to 4, the sound radiating control structure according to this embodiment can be configured in detail as follows. As shown in Figs. 1 to 3, the sound radiating control structure can have a plurality of first vibrating bodies 11 and a plurality of second vibrating bodies 12, in which case, each of a1 and b1 above is an integer of 2 or more. The number of first vibrating bodies 11 (= a1) and the number of second vibrating bodies 12 (= b1) can be the same or different. At least one of a1 and b1 can be set to 1.

[0045] As shown in FIG. 1, the multiple first vibrating bodies 11 and the multiple second vibrating bodies 12 are arranged such that the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 are alternately arranged in a plan view. As an example, the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 can be alternately arranged along an imaginary plane. The imaginary plane is a flat surface. However, the imaginary plane can be a curved surface. The imaginary plane can also be formed to include at least one flat surface and at least one curved surface.

[0046] Furthermore, the radiation surface portions 11a, 12a of the multiple first vibrating bodies 11 and the multiple second vibrating bodies 12 can be arranged in a matrix in a plan view. However, the radiation surface portions of the multiple first vibrating bodies and the multiple second vibrating bodies can also be arranged in a state other than a matrix in a plan view.

[0047] As shown in Figures 2 and 3, the first and second vibrating bodies 11 and 12 have back surfaces 11b and 12b facing the opposite side to the radiation surface portions 11a and 12a. As shown in Figure 1, the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 are arranged at a distance from each other in a plan view. The lower limit value of the maximum separation distance h1 between the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 is set so that the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 can excite the air in the radiation space R independently of each other.

[0048] 1 to 4, the resonance frequency f 11 ,f12 The difference in the resonant frequency f of the first and second vibrating bodies 11, 12 can be achieved by differences in the shapes, dimensions, size, density, weight, elastic modulus, material, etc. of the first and second vibrating bodies 11, 12. For example, as shown in Figs. 1 to 3, the first and second vibrating bodies 11, 12 can each be formed in a plate shape. In this case, the resonant frequency f of the first and second vibrating bodies 11, 12 can be achieved by differences in the shapes, dimensions, size, density, weight, elastic modulus, material, etc. of the first and second vibrating bodies 11, 12. 11 ,f 12 The difference is the thickness t of the first and second vibrating bodies 11 and 12. 11 ,t 12 This can be achieved by varying

[0049] As shown in Figures 1 to 3, each of the first and second vibrating bodies 11, 12 can be formed in a flat plate shape. However, at least one of the first and second vibrating bodies can be formed in a shape other than a plate shape. At least one of the first and second vibrating bodies can be formed in a membrane shape. At least one of the first and second vibrating bodies can be formed in a plate shape including a curved portion.

[0050] 1, each of the first and second vibrating bodies 11 and 12 is formed in a substantially rectangular shape in a plan view. Also, each of the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 is formed in a substantially rectangular shape in a plan view. Furthermore, each of the first and second vibrating bodies 11 and 12, particularly the radiation surface portions 11a and 12a thereof, can be formed in a substantially rectangular shape, particularly a substantially square shape, in a plan view.

[0051] However, at least one of the first and second vibrating bodies may be formed into a shape other than a substantially rectangular shape in a plan view. Furthermore, at least one of the radiation surface portions of the first and second vibrating bodies may also be formed into a shape other than a substantially rectangular shape in a plan view.

[0052] 1, the first and second vibrating bodies 11, 12 are formed to have substantially the same shape and size in a plan view. The radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 are also formed to have substantially the same shape and size in a plan view.

[0053] However, the first and second vibrating bodies can be formed to have different shapes and sizes in a plan view. The radiation surface portions of the first and second vibrating bodies can also be formed to have different shapes and sizes in a plan view.

[0054] 2 and 3, the sound radiation control structure has a support 13 configured to support the first and second vibrating bodies 11, 12. Specifically, the support 13 supports the outer peripheral edge portions 11c, 12c of the first and second vibrating bodies 11, 12 from the rear surface portions 11b, 12b of the first and second vibrating bodies 11, 12. The support 13 is located on the rear surface portions 11b, 12b side of the first and second vibrating bodies 11, 12.

[0055] The support 13 has a support portion 13a configured to support the first and second vibrating bodies 11 and 12. Furthermore, the support portion 13a is configured to support a plurality of the first vibrating bodies 11 and a plurality of the second vibrating bodies 12. The support portion 13a is a rigid body. However, the support portion may also be configured as an elastic body.

[0056] The support portion 13a is formed along the outer peripheral edges 11c, 12c of the first and second vibrating bodies 11, 12. Furthermore, the support portion 13a is formed along the outer peripheral edges 11c, 12c of the plurality of first vibrating bodies 11 and the plurality of second vibrating bodies 12. The outer peripheral edges 11c, 12c of the plurality of first vibrating bodies 11 and the plurality of second vibrating bodies 12 are in contact with and fixed to a surface portion 13b of the support portion 13a.

[0057] Furthermore, the support 13 has an outer peripheral frame portion 13c arranged to surround all of the first and second vibrating bodies 11 and 12 in a plan view. The outer peripheral frame portion 13c is a rigid body. The outer peripheral frame portion 13c has a surface portion 13d facing the radiation space R. This surface portion 13d is arranged along the above-mentioned imaginary plane together with the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12.

[0058] Furthermore, the outer peripheral frame portion 13c is arranged, in a plan view, to be spaced apart from the adjacent outer peripheral edge portions 11c, 12c of the first and second vibrating bodies 11, 12. However, the support body may be configured not to have an outer peripheral frame portion.

[0059] The resonance frequency f of the first and second vibrating bodies 11 and 12 is 11 ,f 12 The lower limit of the interval between the first and second vibrating bodies 11 and 12 (hereinafter referred to as the "resonant frequency interval") can be set to about 5 Hz, taking into consideration the effect on the vibration frequency characteristics of attenuation in the material of the first and second vibrating bodies 11 and 12. The sound radiating control structure has two types of vibrating bodies, like the first and second vibrating bodies 11 and 12 described above. However, the sound radiating control structure can also have three or more types of vibrating bodies. In this case, the relationship between the different types of vibrating bodies is the same as the relationship between the first and second vibrating bodies 11 and 12 described above.

[0060] "Design support method for sound radiation control structures" The design support method for a radiated sound control structure according to this embodiment is generally carried out as follows. The design support method for a radiated sound control structure is used to design a radiated sound control structure according to this embodiment so that a radiated sound can be radiated toward a predetermined radiation space R based on an input sound and the radiated sound can be controlled.

[0061] The design support method for a sound radiating control structure includes a design support step of provisionally determining the configuration of a first vibrating body 11 and a second vibrating body 12 having a specific natural vibration mode, and determining an arrangement in which the first and second vibrating bodies 11 and 12 are adjacent to each other. In this design support step, the first and second vibrating bodies 11 and 12 each have a radiating element 11a, 12a facing a radiation space R, and a resonant frequency f of a specific natural vibration mode in the first and second vibrating bodies 11 and 12 is determined. 11 ,f 12 are different from each other.

[0062] In the design support process, the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 are arranged with a gap therebetween. The resonance frequencies f 11 ,f 12 In order to generate an interference effect between the first and second vibrating bodies 11 and 12 so as to reduce the radiated sound, the provisionally determined configurations of the first and second vibrating bodies 11 and 12 are adjusted so that the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 can excite the air in the radiation space R independently of each other and in opposite phase to each other.

[0063] Furthermore, the design support method for the sound radiating control structure according to this embodiment can be implemented generally as follows: In the design support process, when a1 and b1 are each an integer equal to or greater than 1, the sound radiating control structure has a1 first vibrating bodies 11 and b1 second vibrating bodies 12.

[0064] Furthermore, assuming the existence of a first hypothetical structure in which the sound radiation control structure is modified so that b1 first vibrators 11 are installed instead of b1 second vibrators 12, and a second hypothetical structure in which the sound radiation control structure is modified so that a1 second vibrators 12 are installed instead of a1 first vibrators 11, the resonance frequency f 11 ,f 12 A given intermediate frequency f 11-12 The intermediate frequency f 11-12At least one of the shape, dimensions, density, elastic modulus and material of each of the provisionally determined first and second vibrating bodies 11, 12 is adjusted so that the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a1 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b1.

[0065] The design support method of the sound radiating control structure according to this embodiment can be carried out in detail as follows. In the design support process, the maximum separation distance h1 between the first and second vibrating bodies 11 and 12 is set to a value equal to the resonant frequency f of a specific natural vibration mode of the first and second vibrating bodies 11 and 12. 11 ,f 12 The wavelength λ is calculated based on either 11 ,λ 12 The first and second vibrating bodies 11, 12 can be installed as follows.

[0066] In addition, in the design support process, at least one of the shape, size, density, elastic modulus, and material of each of the first and second vibrating bodies 11, 12 can be adjusted so that the orders of the specific natural vibration modes of the first and second vibrating bodies 11, 12 are the same. For example, such an order can be the first order. However, the orders of the specific natural vibration modes of the first and second vibrating bodies can also be different.

[0067] "Mechanism for controlling radiated sound" The mechanism of radiated sound control according to this embodiment will be described below. Here, the mechanism of radiated sound control will be described from the viewpoint that the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 excite the air in the radiation space R. Furthermore, in the following description, the radiation surface portions 11a, 12a of the flat plate-shaped first and second vibrating bodies 11, 12 are arranged alternately along an imaginary plane.

[0068] Considering the vibration of an infinite flat plate, when the radiation surfaces 11a, 12a are the vibration surfaces, the imaginary plane is the plane on the x and y coordinates, and the radiation space R is the space on the positive side of the z coordinate, the surface vibration velocity u (m / s) in the surface normal direction of the radiation surfaces 11a, 12a is given by the following (Equation 1): In (Equation 1), U is the vibration velocity complex amplitude (m / s), and Φ is the phase term of the surface vibration velocity.

[0069]

number

[0070] If the radiation space R is a free space with no other sound sources, the sound pressure p (Pa) in the radiation space R is expressed by the following (Equation 2) based on the wave equation and boundary conditions. In (Equation 2), k is the norm (rad / m) of the radiated sound wave number vector, i is the imaginary unit, and k 0z is the z-component of the vibration surface wave vector (rad / m), and z0 is the characteristic impedance of air (Pa s / m).

[0071]

number

[0072] In addition, the z-direction component k of the vibration surface wave number vector 0z (rad / m) is as shown in the following (Equation 3). Note that k 0x and k 0y are the x-component (rad / m) and y-component (rad / m) of the vibration surface wave number vector, respectively.

[0073]

number

[0074] Next, taking into account the evanescent wave and radiation power, k in the above (Equation 2) zbecomes a pure imaginary number when the norm k0 of the two-dimensional wave vector of the vibration surface is greater than the norm k of the wave vector of the radiated sound. In this case, the radiated sound pressure decays exponentially with respect to the z component. As a result, the phase of p becomes as shown in the following (Equation 4).

[0075]

number

[0076] According to the above formula (4), the radiated sound pressure is perpendicular to the vibration velocity. Therefore, the z-component Iz of the time-averaged active intensity, which is the in-phase component of the product of sound pressure and particle velocity, is approximately 0 (zero) as shown in the following formula (5), and there is essentially no radiation of net sound power to distant locations. In formula (5), the symbol indicated by "*" represents a complex conjugate.

[0077]

number

[0078] Here, looking at the conditions for the generation of evanescent waves from a different perspective, the following condition (Equation 6) can be derived: In Equation 6, λ is the wavelength (m) of the radiated sound, and λ0 is the wavelength (m) on the vibration surface.

[0079]

number

[0080] According to the above formula (6), when the anti-phase vibration region is located at a distance shorter than half the wavelength λ of the radiated sound, the net radiation of sound power to a distant location is not reliably generated as described above. In this case, if the interaction between the anti-phase vibration regions causes circulation in the particle motion, it is known that the radiation efficiency of each region becomes approximately 0 (zero). This phenomenon is called hydrodynamic short circuit. Furthermore, as the distance to the anti-phase vibration region increases beyond half the wavelength λ of the radiated sound, the effect of reducing the radiation of sound power decreases. And when the distance to the anti-phase vibration region increases beyond the wavelength λ of the radiated sound, the effect of reducing the radiation of sound power is almost not obtained.

[0081] Based on this mechanism, the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 can be fabricated as surfaces that vibrate but do not substantially radiate sound. According to the above mechanism, the maximum separation distance h1 between the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 is set to the resonant frequency f 11 ,f 12 The wavelength λ is calculated based on either 11 ,λ 12 More preferably, the maximum separation distance h1 should be set to be equal to or less than the resonant frequency f 11 ,f 12 The wavelength λ is calculated based on either 11 ,λ 12 In the sound radiating control structure according to this embodiment, the sound radiating amount can be efficiently reduced.

[0082] As described above, the radiated sound control structure and the design support method thereof according to this embodiment can provide the following actions and effects. The radiated sound control structure according to this embodiment is a structure that is configured to be able to radiate radiated sound toward a predetermined radiation space R based on an input sound and to be able to control the radiated sound, and includes a first vibrating body 11 and a second vibrating body 12 having a specific natural vibration mode, and a resonant frequency f of the specific natural vibration mode in the first and second vibrating bodies 11 and 12.11 ,f 12 are different from each other, the first and second vibrating bodies 11 and 12 each have a radiation surface portion 11a, 12a facing the radiation space R, the first and second vibrating bodies 11 and 12 are arranged adjacent to each other, and the radiation surface portions 11a, 12a of the first and second vibrating bodies 11 and 12 have a resonance frequency f 11 ,f 12 They are spaced apart so as to be able to excite the air in the radiation space R independently of each other and in opposite phase to each other, so as to produce an interference effect between them to reduce radiated sound.

[0083] According to such a sound radiation control structure, the first and second vibrators 11 and 12 are vibrated at different resonance frequencies f 11 ,f 12 The constraints of arranging the first and second vibrating bodies 11, 12 adjacent to each other with a gap between them so that the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 can excite the air in the radiation space R independently of each other, are particularly small in limiting the structure compared to conventional structures. Therefore, the degree of freedom in designing the sound radiating control structure can be improved.

[0084] In the first and second vibrating bodies 11 and 12 having a structure based on the above constraints, their resonant frequencies f 11 ,f 12 The interference between the two components makes it possible to easily and efficiently reduce the sound radiated from the sound radiating control structure. Therefore, the sound radiated from the sound radiating control structure can be easily and efficiently reduced, and the degree of freedom in design can be improved.

[0085] In the sound radiating control structure according to this embodiment, the maximum separation distance h1 between the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 is set to be smaller than the resonance frequency f 11 ,f 12 The wavelength λ is calculated based on either 11 ,λ 12According to such a sound radiation control structure, under the condition of the maximum separation distance h1, the resonant frequency f 11 ,f 12 Therefore, interference between the two can be efficiently generated, and radiated sound can be efficiently reduced.

[0086] The sound radiating control structure according to this embodiment includes a1 first vibrating bodies 11 and b1 second vibrating bodies 12, where a1 and b1 are integers equal to or greater than 1. In the case of assuming the existence of a first imaginary structure in which the sound radiating control structure is modified so that b1 first vibrating bodies 11 are installed instead of the b1 second vibrating bodies 12, and a second imaginary structure in which the sound radiating control structure is modified so that a1 second vibrating bodies 12 are installed instead of the a1 first vibrating bodies 11, the first and second vibrating bodies 11 and 12 have their resonant frequencies f 11 ,f 12 A given intermediate frequency f 11-12 In order to generate interference that minimizes the radiated sound at intermediate frequency f 11-12 The value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a1 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b1.

[0087] According to such a sound radiation control structure, the resonant frequency f 11 ,f 12 Intermediate frequency f 11-12 In particular, when it is desired to reduce the radiated sound of a desired frequency, the desired frequency is set to an intermediate frequency f 11-12 Therefore, the radiated sound can be reduced easily and efficiently.

[0088] In the sound radiating control structure according to this embodiment, the order of the specific natural vibration mode of the first and second vibrating bodies 11, 12 is the same. According to such a sound radiating control structure, when the order of the specific natural vibration mode of the first and second vibrating bodies 11, 12 is the same, particularly when the order of the specific natural vibration mode of the first and second vibrating bodies 11, 12 is the first order, the resonant frequency f 11 ,f 12 An efficient interference effect occurs between them, and the sound radiated from the sound radiating control structure can be efficiently reduced.

[0089] The design support method for a sound radiating control structure according to this embodiment is a design support method used for designing a sound radiating control structure so as to be able to radiate sound toward a predetermined radiation space R based on an input sound and to be able to control the radiated sound, and is a design support process for provisionally determining the configuration of a first vibrating body 11 and a second vibrating body 12 having a specific natural vibration mode and determining an arrangement in which the first and second vibrating bodies 11, 12 are adjacent to each other, the first and second vibrating bodies 11, 12 each having a radiation surface portion 11a, 12a facing the radiation space R, and a resonant frequency f of the specific natural vibration mode in the first and second vibrating bodies 11, 12 is determined. 11 ,f 12 The design support step includes a design support step in which the resonance frequencies f of the first and second vibrating bodies 11 and 12 are different from each other and the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 are arranged with a gap therebetween, and in the design support step, 11 ,f 12 In order to generate an interference effect between the first and second vibrating bodies 11 and 12 so as to reduce the radiated sound, the provisionally determined configurations of the first and second vibrating bodies 11 and 12 are adjusted so that the radiation surface portions 11a and 12a of the first and second vibrating bodies 11 and 12 can excite the air in the radiation space R independently of each other and in opposite phase to each other.

[0090] According to such a design support method for a sound radiating control structure, the first and second vibrating bodies 11 and 12 are vibrated at different resonant frequencies f 11 ,f 12The constraints of arranging the first and second vibrating bodies 11, 12 adjacent to each other with a gap between them so that the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 can excite the air in the radiation space R independently of each other, are particularly small in limiting the structure compared to conventional structures. Therefore, the sound radiating control structure can be manufactured with a high degree of design freedom.

[0091] In the first and second vibrating bodies 11 and 12 having a structure based on the above constraints, their resonant frequencies f 11 ,f 12 The interference between the two components makes it possible to easily and efficiently reduce the sound radiated from the sound radiating control structure. Therefore, the sound radiating control structure can be manufactured easily and with a high degree of design freedom, and the sound radiated from the manufactured sound radiating control structure can be efficiently reduced.

[0092] In the design support method of the radiated sound control structure according to this embodiment, in the design support step, when a1 and b1 are each an integer of 1 or more, the radiated sound control structure has a1 first vibrating bodies 11 and b1 second vibrating bodies 12, and it is assumed that there exist a first imaginary structure in which the radiated sound control structure is modified so that b1 first vibrating bodies 11 are installed instead of the b1 second vibrating bodies 12, and a second imaginary structure in which the radiated sound control structure is modified so that a1 second vibrating bodies 12 are installed instead of the a1 first vibrating bodies 11, the resonant frequencies f 11 ,f 12 A given intermediate frequency f 11-12 In order to generate interference that minimizes the radiated sound at intermediate frequency f 11-12 At least one of the shape, dimensions, density, elastic modulus and material of each of the provisionally determined first and second vibrating bodies 11, 12 is adjusted so that the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a1 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b1.

[0093] According to such a design support method for a sound radiation control structure, the resonant frequency f 11 ,f 12 A given intermediate frequency f 11-12 In particular, when it is desired to reduce the radiated sound of a desired frequency, the desired frequency is set to an intermediate frequency f 11-12 Therefore, the radiated sound can be reduced easily and efficiently.

[0094] "Second embodiment" A sound radiating control structure according to the second embodiment and a design support method thereof will be described.

[0095] "Outline of sound radiation control structure" 5 to 8, the radiated sound control structure according to this embodiment is generally configured as follows: The radiated sound control structure is configured to be able to radiate radiated sound toward a predetermined radiation space R based on an input sound, and to be able to control the radiated sound.

[0096] In FIG. 8, the horizontal axis f indicates frequency (Hz), and the vertical axis V on the left side of the page indicates the value obtained by multiplying the magnitude of the average vibration volume velocity by a weight (m 3 8, the vertical axis C2 indicates the frequency and the transmission loss in the radiation control structure, the dashed line D2 indicates the frequency and the value obtained by multiplying the magnitude of the average vibration volume velocity by a weight in a first hypothetical structure described later, and the dashed line E2 indicates the frequency and the value obtained by multiplying the magnitude of the average vibration volume velocity by a weight in a second hypothetical structure described later.

[0097] As shown in Figures 5 to 7, the sound radiation control structure has a first resonator 21 and a second resonator 22. With reference to Figures 5 to 8, each of the first and second resonators 21 and 22 has a specific natural acoustic mode. The resonant frequency f 21 ,f 22The first and second resonators 21 and 22 have openings 21a and 22a that open toward the radiation space R, respectively.

[0098] The first and second resonators 21 and 22 are arranged adjacent to each other. The openings 21a and 22a of the first and second resonators 21 and 22 are arranged so that the resonant frequencies f 21 ,f 22 They are spaced apart so as to be able to excite the air in the radiation space R independently of each other and in opposite phase to each other, so as to produce an interference effect between them to reduce radiated sound.

[0099] Further, the sound radiating control structure according to this embodiment can be roughly configured as follows. With reference to Figs. 5 and 8, the maximum separation distance h2 between the openings 21a, 22a of the first and second resonators 21, 22 is set to 1 / 2 times the resonant frequency f 21 ,f 22 The wavelength λ is calculated based on either 21 ,λ 22 It can be as follows:

[0100] The sound radiating control structure has a2 first resonators 21 and b2 second resonators 22, where a2 and b2 are each an integer equal to or greater than 1. Here, the existence of a first virtual structure in which the sound radiating control structure is modified so that b2 first resonators 21 are installed instead of the b2 second resonators 22, and a second virtual structure in which the sound radiating control structure is modified so that a2 second resonators 22 are installed instead of the a2 first resonators 21, is assumed.

[0101] In this case, the first and second resonators 21 and 22 have a resonant frequency f 21 ,f 22 A given intermediate frequency f 21-22 In order to generate interference that minimizes the radiated sound at intermediate frequency f 21-22The value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a2 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b2.

[0102] Also, the orders of the specific natural acoustic modes of the first and second resonators 21, 22 may be the same. For example, such an order may be the first order. However, the orders of the specific natural acoustic modes of the first and second resonators may be different.

[0103] "Details of sound radiation control structure" 5 to 8, the sound radiating control structure according to this embodiment can be configured in detail as follows. First, the first and second resonators 21, 22 can be rigid bodies. As shown in FIGS. 5 to 7, the sound radiating control structure can have a plurality of first resonators 21 and a plurality of second resonators 22, in which case, each of a2 and b2 above is an integer of 2 or more. The number of first resonators 21 (= a2) and the number of second resonators 22 (= b2) can be the same or different. At least one of a2 and b2 can be set to 1.

[0104] As shown in FIG. 5, the multiple first resonators 21 and the multiple second resonators 22 are arranged such that the openings 21a, 22a of the first and second resonators 21, 22 are alternately arranged in a plan view. As shown in FIGS. 6 and 7, as an example, the openings 21a, 22a of the first and second resonators 21, 22 can be alternately arranged along a virtual plane. The virtual plane is a flat surface. However, the virtual plane can be a curved surface. The virtual plane can also be formed to include at least one flat surface and at least one curved surface.

[0105] 5, the openings 21a, 22a of the multiple first resonators 21 and the multiple second resonators 22 can be arranged in a matrix in a plan view. However, the openings of the multiple first resonators and the multiple second resonators can also be arranged in a state other than a matrix in a plan view.

[0106] As shown in Fig. 5, the openings 21a, 22a of the first and second resonators 21, 22 are arranged with a gap between them in a plan view. The lower limit of the maximum separation distance h2 between the openings 21a, 22a of the first and second resonators 21, 22 is set so that the openings 21a, 22a of the first and second resonators 21, 22 can excite the air in the radiation space R independently of each other. In Figs. 5 to 7, each of the first and second resonators 21, 22 has one opening 21a, 22a. However, at least one of the first and second resonators may have two or more openings.

[0107] 5 to 7, the first and second resonators 21, 22 each have a surface portion 21b, 22b facing the radiation space R. Openings 21a, 22a are formed in the surface portions 21b, 22b of the first and second resonators 21, 22, respectively. As an example, the surface portions 21b, 22b of the first and second resonators 21, 22 can be arranged along an imaginary plane.

[0108] 6 and 7, the first and second resonators 21 and 22 have back surfaces 21c and 22c facing the openings 21a and 22a, respectively. The first and second resonators 21 and 22 have peripheral surfaces 21d and 22d extending between the front surfaces 21b and 22b and the back surfaces 21c and 22c, respectively.

[0109] The first and second resonators 21 and 22 each have a resonance space 21e or 22e surrounded by a front surface 21b or 22b, a rear surface 21c or 22c, and a peripheral surface 21d or 22d. In the first and second resonators 21 and 22, the resonance space 21e or 22e is connected to the radiation space R via the openings 21a or 22a.

[0110] The resonant frequency f 21 ,f 22 The differences can also be brought about by differences in the shape, various dimensions, size, etc. of the openings 21a, 22a in the first and second resonators 21, 22, differences in the shape, various dimensions, capacity, cross-sectional size, etc. of the resonance spaces 21e, 22e in the first and second resonators 21, 22, and differences in the path lengths between the openings 21a, 22a and the back portions 21c, 22c in the first and second resonators 21, 22, etc.

[0111] For example, as shown in Figures 5 to 7, the openings 21a, 22a in the first and second resonators 21, 22 may be different in size. The openings 21a, 22a may be smaller than the cross sections of the resonance spaces 21e, 22e. However, the openings may be substantially equal in size to the cross sections of the resonance spaces.

[0112] Also, the shape, volume, and cross-sectional size of the resonance spaces 21e, 22e of the first and second resonators 21, 22 can be substantially the same. However, at least one of the shape, volume, and cross-sectional size of the resonance spaces of the first and second resonators can be different.

[0113] In each of the first and second resonators 21 and 22, the resonance space 21e, 22e is formed to extend linearly between the opening 21a, 22a and the back surface 21c, 22c. However, in at least one of the first and second resonators, the resonance space may be formed to extend while curving between the opening and the back surface.

[0114] The sound radiation control structure has an outer peripheral frame 23 arranged to surround all of the first and second resonators 21, 22 in a plan view. The outer peripheral frame 23 is a rigid body. The outer peripheral frame 23 has a surface portion 23a arranged along a virtual plane together with the surface portions 21b, 22b of the first and second resonators 21, 22.

[0115] The outer peripheral edge portion 23b of the outer peripheral frame 23 is disposed with a gap between the openings 21a, 22a of the first and second resonators 21, 22 adjacent to the outer peripheral frame 23. The resonant frequencies f 21 ,f 22 The lower limit of the interval between the first and second resonators 21 and 22 (hereinafter referred to as the "resonant frequency interval") can be set to about 5 Hz, taking into consideration the effect of damping in the material of the first and second resonators 21 and 22 on the vibration frequency characteristics.

[0116] The first and second resonators 21, 22 and the outer peripheral frame 23 are integrally formed. However, at least one of the first and second resonators and the outer peripheral frame may be formed separately from the others. The sound radiating control structure may also be configured not to have an outer peripheral frame.

[0117] "Design support method for sound radiation control structures" The design support method for a radiated sound control structure according to this embodiment is generally carried out as follows. The design support method for a radiated sound control structure is used to design a radiated sound control structure according to this embodiment so that a radiated sound can be radiated toward a predetermined radiation space R based on an input sound and the radiated sound can be controlled.

[0118] The design support method for a sound radiation control structure includes a design support step of provisionally determining the configuration of a first resonator 21 and a second resonator 22 having a specific natural acoustic mode, and determining an arrangement in which the first and second resonators 21, 22 are adjacent to each other. In this design support step, the first and second resonators 21, 22 each have an opening 21a, 22a that opens toward the radiation space R, and the resonant frequency f of the specific natural acoustic mode in the first and second resonators 21, 22 is determined. 21 ,f 22 are different from each other.

[0119] In the design support process, the openings 21a, 22a of the first and second resonators 21, 22 are arranged with a gap between them. The resonant frequencies f 21 ,f 22In order to generate an interference effect between the first and second resonators 21, 22 so as to reduce the radiated sound, the provisionally determined configurations of the first and second resonators 21, 22 are adjusted so that the openings 21a, 22a of the first and second resonators 21, 22 can excite the air in the radiation space R independently of each other and in opposite phase to each other.

[0120] Furthermore, the design support method for the sound radiating control structure according to this embodiment can be implemented generally as follows: In the design support process, when a2 and b2 are each an integer equal to or greater than 1, the sound radiating control structure has a2 first resonators 21 and b2 second resonators 22.

[0121] In this design support process, it is assumed that there exist a first hypothetical structure in which the sound radiation control structure is modified so that b2 first resonators 21 are installed instead of b2 second resonators 22, and a second hypothetical structure in which the sound radiation control structure is modified so that a2 second resonators 22 are installed instead of a2 first resonators 21. In this hypothetical structure, the resonant frequencies f 21 ,f 22 A given intermediate frequency f 21-22 In order to generate interference that minimizes the radiated sound at intermediate frequency f 21-22 At least one of the shape, dimensions, density, elastic modulus and material of each of the provisionally determined first and second resonators 21, 22 is adjusted so that the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a2 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b2.

[0122] The design support method of the sound radiating control structure according to this embodiment can be carried out in detail as follows. In the design support process, the maximum separation distance h2 between the first and second resonators 21, 22 is set to a value equal to the resonant frequency f of a specific natural acoustic mode in the first and second resonators 21, 22. 21 ,f 22 The wavelength λ is calculated based on either 21 ,λ 22The first and second resonators 21, 22 can be disposed as follows.

[0123] In the design support process, at least one of the shape, size, density, elastic modulus, and material of each of the first and second resonators 21, 22 can be adjusted so that the orders of the specific natural acoustic modes of the first and second resonators 21, 22 are the same. For example, such an order can be the first order. However, the orders of the specific natural acoustic modes of the first and second resonators can be different.

[0124] "Mechanism for controlling radiated sound" The mechanism of radiated sound control according to this embodiment is similar to that according to the first embodiment in that the openings 21a, 22a of the first and second resonators 21, 22 excite the air in the radiation space R. Therefore, the mechanism of radiated sound control according to this embodiment will be omitted.

[0125] As described above, the radiated sound control structure and the design support method thereof according to this embodiment can provide the following actions and effects. The radiated sound control structure according to this embodiment is a structure that is configured to be able to radiate radiated sound toward a predetermined radiation space R based on an input sound and to be able to control the radiated sound, and includes a first resonator 21 and a second resonator 22 having a specific natural acoustic mode, and a resonant frequency f of the specific natural acoustic mode in the first and second resonators 21 and 22. 21 ,f 22 The first and second resonators 21 and 22 have openings 21a and 22a that open toward the radiation space R, the first and second resonators 21 and 22 are arranged adjacent to each other, and the openings 21a and 22a of the first and second resonators 21 and 22 are different from each other in terms of the resonant frequency f 21 ,f 22 They are spaced apart so as to be able to excite the air in the radiation space R independently of each other and in opposite phase to each other, so as to produce an interference effect between them to reduce radiated sound.

[0126] According to such a sound radiation control structure, the first and second resonators 21 and 22 are arranged to have different resonant frequencies f 21 ,f 22 The constraints of arranging the first and second resonators 21, 22 adjacent to each other with a gap between them so that the openings 21a, 22a of the first and second resonators 21, 22 can excite the air in the radiation space R independently of each other, are particularly small in limiting the structure compared to conventional structures. Therefore, the degree of freedom in designing the sound radiation control structure can be improved.

[0127] In the first and second resonators 21 and 22 having the structure based on the above constraints, the resonant frequencies f 21 ,f 22 The interference between the two components makes it possible to easily and efficiently reduce the sound radiated from the sound radiating control structure. Therefore, the sound radiated from the sound radiating control structure can be easily and efficiently reduced, and the degree of freedom in design can be improved.

[0128] In the sound radiation control structure according to this embodiment, the maximum separation distance h2 between the openings 21a, 22a of the first and second resonators 21, 22 is set to be equal to or smaller than the resonant frequency f 21 ,f 22 The wavelength λ is calculated based on either 21 ,λ 22 According to such a sound radiation control structure, under the condition of the maximum separation distance h2, the resonant frequency f 21 ,f 22 Therefore, interference between the two can be efficiently generated, and radiated sound can be efficiently reduced.

[0129] The radiated sound control structure according to this embodiment includes a2 first resonators 21 and b2 second resonators 22, where a2 and b2 are integers equal to or greater than 1. In the case of assuming the existence of a first imaginary structure in which the radiated sound control structure is modified so that b2 first resonators 21 are installed instead of the b2 second resonators 22, and a second imaginary structure in which the radiated sound control structure is modified so that a2 second resonators 22 are installed instead of the a2 first resonators 21, the first and second resonators 21, 22 have their resonant frequencies f 21 ,f 22 A given intermediate frequency f 21-22 In order to generate interference that minimizes the radiated sound at intermediate frequency f 21-22 The value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a2 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b2.

[0130] According to such a sound radiation control structure, the resonant frequency f 21 ,f 22 Intermediate frequency f 21-22 In particular, when it is desired to reduce the radiated sound of a desired frequency, the desired frequency is set to an intermediate frequency f 21-22 Therefore, the radiated sound can be reduced easily and efficiently.

[0131] In the radiated sound control structure according to this embodiment, the order of the specific natural acoustic mode of the first and second resonators 21, 22 is the same. According to such a radiated sound control structure, when the order of the specific natural acoustic mode of the first and second resonators 21, 22 is the same, particularly when the order of the specific natural acoustic mode of the first and second resonators 21, 22 is the first order, the resonant frequency f 21 ,f 22 An efficient interference effect occurs between them, and the sound radiated from the sound radiating control structure can be efficiently reduced.

[0132] The design support method for a sound radiating control structure according to this embodiment is a design support method used for designing a sound radiating control structure so as to be capable of radiating a sound radiating toward a predetermined radiation space R based on an input sound and to be capable of controlling the radiated sound, and is a design support process for provisionally determining the configuration of a first resonator 21 and a second resonator 22 having a specific natural acoustic mode and determining an arrangement in which the first and second resonators 21, 22 are adjacent to each other, the first and second resonators 21, 22 each having an opening 21a, 22a that opens toward the radiation space R, and a resonant frequency f of the specific natural acoustic mode in the first and second resonators 21, 22 is determined. 21 ,f 22 The design support step includes a design support step in which the resonant frequencies f of the first and second resonators 21 and 22 are different from each other and the openings 21a and 22a of the first and second resonators 21 and 22 are arranged at an interval. 21 ,f 22 In order to generate an interference effect between the first and second resonators 21, 22 so as to reduce the radiated sound, the provisionally determined configurations of the first and second resonators 21, 22 are adjusted so that the openings 21a, 22a of the first and second resonators 21, 22 can excite the air in the radiation space R independently of each other and in opposite phase to each other.

[0133] According to such a design support method for a sound radiating control structure, the first and second resonators 21 and 22 are arranged to have different resonant frequencies f 21 ,f 22 The constraints of arranging the first and second resonators 21, 22 adjacent to each other with a gap between them so that the openings 21a, 22a of the first and second resonators 21, 22 can excite the air in the radiation space R independently of each other, are particularly small in restricting the structure compared to conventional structures. Therefore, the sound radiation control structure can be manufactured with a high degree of design freedom.

[0134] In the first and second resonators 21 and 22 having the structure based on the above constraints, the resonant frequencies f 21 ,f 22The interference between the two components makes it possible to easily and efficiently reduce the sound radiated from the sound radiating control structure. Therefore, the sound radiating control structure can be manufactured easily and with a high degree of design freedom, and the sound radiated from the manufactured sound radiating control structure can be efficiently reduced.

[0135] In the design support method of the radiated sound control structure according to this embodiment, in the design support step, when a2 and b2 are each an integer of 1 or more, the radiated sound control structure has a2 first resonators 21 and b2 second resonators 22, and it is assumed that there exist a first virtual structure in which the radiated sound control structure is modified so that b2 first resonators 21 are installed instead of the b2 second resonators 22, and a second virtual structure in which the radiated sound control structure is modified so that a2 second resonators 22 are installed instead of the a2 first resonators 21, the resonant frequencies f 21 ,f 22 A given intermediate frequency f 21-22 In order to generate interference that minimizes the radiated sound at intermediate frequency f 11-12 At least one of the shape, dimensions, density, elastic modulus and material of each of the provisionally determined first and second resonators 21, 22 is adjusted so that the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the first virtual structure by a2 is substantially equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air of the radiation space R excited by the second virtual structure by b2.

[0136] According to such a design support method for a sound radiation control structure, the resonant frequency f 21 ,f 22 A given intermediate frequency f 21-22 In particular, when it is desired to reduce the radiated sound of a desired frequency, the desired frequency is set to an intermediate frequency f 21-22 Therefore, the radiated sound can be reduced easily and efficiently.

[0137] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and the present invention can be modified and changed based on the technical concept thereof. EXAMPLES

[0138] Examples 1 and 2 will be described.

[0139] "Example 1" Example 1 will be described. In Example 1, an analytical model of a radiated sound control structure, a first virtual structure, and a second virtual structure similar to those of the first embodiment was created in a simulation using numerical analysis. Specifically, the radiated sound control structure of Example 1 had 13 (a1=13) first vibrating bodies 11 and 12 (b1=12) second vibrating bodies 12.

[0140] In the sound radiating control structure of Example 1, 13 first vibrating bodies 11 and 12 second vibrating bodies 12 are arranged such that the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 are alternately arranged along an imaginary plane. The radiation surface portions 11a, 12a of the 13 first vibrating bodies 11 and the 12 second vibrating bodies 12 are arranged in a matrix in plan view. Each of the first and second vibrating bodies 11, 12 is formed in a square shape in plan view.

[0141] The length of each side of the first and second vibrating bodies 11 and 12 was 100 mm. 11 The thickness t of the second vibrating body 12 was 1.0 mm. 12 The maximum separation distance h1 between the radiation surface portions 11a, 12a of the first and second vibrating bodies 11, 12 was 2 mm. Each of the first and second vibrating bodies 11, 12 was made of polyamide resin.

[0142] The first virtual structure was a structure obtained by modifying the above-mentioned sound radiating control structure so that 12 first vibrating bodies 11 were installed instead of the 12 second vibrating bodies 12. The second virtual structure was a structure obtained by modifying the above-mentioned sound radiating control structure so that 13 second vibrating bodies 12 were installed instead of the 13 first vibrating bodies 11.

[0143] In the simulation by the above-mentioned numerical analysis, when an input sound is input to the radiated sound control structure, the value (m 3 / s) and the value (m 3 In the simulation using the above numerical analysis, the transmission loss (dB) of radiated sound occurring in the frequency range of 100 Hz to 1000 Hz when an input sound is input to the sound radiation control structure was calculated.

[0144] In Example 1, as shown in FIG. 4, the value (m 3 / s) and the value obtained by multiplying the magnitude of the average vibration volume velocity based on the second hypothetical structure by b1 (m 3 4, the resonance frequency f of a specific natural vibration mode in the first and second vibrating bodies 11 and 12 was calculated. 11 ,f 12 Between the intermediate frequency f 11-12 The transmission loss is maximum at intermediate frequency f 11-12 The radiated noise was reduced the most.

[0145] Furthermore, this intermediate frequency f 11-12 In the example, the value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space R excited by the first virtual structure by a1 was equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space R excited by the second virtual structure by b1. Therefore, it was confirmed that the sound radiating control structure of the example 1 can easily and efficiently reduce the sound radiating, as described above.

[0146] "Example 2" Example 2 will be described. In Example 2, an analytical model of a radiated sound control structure, a first virtual structure, and a second virtual structure similar to those of the second embodiment was created in a simulation using numerical analysis. Specifically, the radiated sound control structure of Example 2 had eight (a2=8) first resonators 21 and eight (b2=8) second resonators 22.

[0147] In the sound radiation control structure of Example 2, eight first resonators 21 and eight second resonators 22 are arranged such that the openings 21a, 22a of the first and second resonators 21, 22 are alternately arranged along a virtual plane. The openings 21a, 22a of the eight first resonators 21 and the eight second resonators 22 are arranged in a matrix in plan view.

[0148] The openings 21a, 22a of the first and second resonators 21, 22 were formed to be different in size. The first and second resonators 21, 22 were formed to be the same except for the openings 21a, 22a. The maximum separation distance h2 between the openings 21a, 22a of the first and second resonators 21, 22 was 35 mm. Each of the first and second resonators 21, 22 was made of polyamide resin.

[0149] The first virtual structure was a structure obtained by modifying the above-mentioned sound radiating control structure so that eight first resonators 21 were installed instead of the eight second resonators 22. The second virtual structure was a structure obtained by modifying the above-mentioned sound radiating control structure so that eight second resonators 22 were installed instead of the eight first resonators 21.

[0150] In the simulation by the above-mentioned numerical analysis, when an input sound is input to the radiated sound control structure, the value (m 3 / s) and the value (m 3In the simulation using the above numerical analysis, the transmission loss (dB) of radiated sound occurring in the frequency range of 100 Hz to 1000 Hz when an input sound is input to the sound radiation control structure was calculated.

[0151] In Example 1, as shown in FIG. 8, the value (m 3 / s) and the value obtained by multiplying the magnitude of the average vibration volume velocity based on the second hypothetical structure by b2 (m 3 8, the resonant frequency f of a specific natural acoustic mode in the first and second resonators 21 and 22 was calculated. 21 ,f 22 Between the intermediate frequency f 21-22 The transmission loss is maximum at intermediate frequency f 21-22 The radiated noise was reduced the most.

[0152] Furthermore, this intermediate frequency f 21-22 In the example, the value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space R excited by the first virtual structure by a2 was equal to the value obtained by multiplying the magnitude of the average vibration volume velocity in the air in the radiation space R excited by the second virtual structure by b2. Therefore, it was confirmed that the sound radiating control structure of the example 2 can easily and efficiently reduce the sound radiating, as described above. [Explanation of symbols]

[0153] 11...first vibrating body (first cell), 12...second vibrating body (second cell), 11a, 12a...radiating surface portion (radiating element) 21...first resonator (first cell), 22...second resonator (second cell), 21a, 22a...openings (radiating elements) R…Radiation space h1,h2…Maximum separation distance f 11 ,f 12 …Resonance frequency (specific frequency), f 21 ,f 22 …Resonance frequency (specific frequency), f 11-12 ,f21-22 ...Intermediate frequency, λ 11 ,λ 12 ,λ 21 ,λ 22 …wavelength

Claims

1. A sound radiation control structure configured to be able to radiate a radiated sound toward a predetermined radiation space based on an input sound and to be able to control the radiated sound, A first cell and a second cell having a specific natural mode, which is a specific natural vibration mode or a specific natural acoustic mode, The first and second cells have resonant frequencies of the specific natural vibration modes or specific natural acoustic modes that are different from each other, each of the first and second cells having a radiating element facing the radiating space; The first and second cells are disposed adjacent to each other, A radiated sound control structure in which the radiating elements of the first and second cells are spaced apart so as to be able to excite the air in the radiation space independently of each other and in anti-phase with respect to each other, so as to create an interference effect to reduce the radiated sound between specific frequencies of the first and second cells.

2. The sound radiating control structure according to claim 1 , wherein the maximum separation distance between the radiating elements of the first and second cells is equal to or less than a wavelength calculated based on one of the specific frequencies of the first and second cells.

3. The cell array includes a number of the first cells and b number of the second cells, where a and b are integers of 1 or more, 2. The sound radiating control structure according to claim 1, wherein, assuming the existence of a first virtual structure in which the sound radiating control structure is modified to have b first cells instead of b second cells, and a second virtual structure in which the sound radiating control structure is modified to have a second cell instead of a first cell, the first and second cells are configured to make the value obtained by multiplying the average vibration volume velocity in the air in the radiation space excited by the first virtual structure by a equal to the value obtained by multiplying the average vibration volume velocity in the air in the radiation space excited by the second virtual structure by b at a predetermined intermediate frequency between these specific frequencies, so as to generate the interference effect so as to most reduce the radiated sound at the predetermined intermediate frequency between these specific frequencies.

4. The sound radiating control structure according to claim 1 , wherein the first and second cells have the same order of a specific eigenmode.

5. the specific natural mode is the specific natural vibration mode, the specific frequency is a resonant frequency of the specific natural vibration mode, the first cell and the second cell are a first vibrating body and a second vibrating body having a radiation surface portion facing the radiation space, The sound radiating control structure according to claim 1 , wherein the radiating element is the radiating surface portion.

6. the specific eigenmode is the specific eigenacoustic mode, the specific frequency is a resonant frequency of the specific natural acoustic mode, The first cell and the second cell are first resonators and second resonators, respectively, having openings that open toward the radiation space, The sound radiating control structure of claim 1 , wherein the radiating element is the opening.

7. A design support method for a sound radiation control structure used to design a sound radiation control structure so as to be able to radiate a sound radiation toward a predetermined radiation space based on an input sound and to be able to control the sound radiation, comprising: a design support step of provisionally determining a configuration of a first cell and a second cell having a specific natural mode which is a specific natural vibration mode or a specific natural acoustic mode, and determining an arrangement of the first and second cells adjacent to each other, wherein each of the first and second cells has a radiation element facing the radiation space, the first and second cells have a resonant frequency of the specific natural vibration mode or a specific frequency which is a resonant frequency of the specific natural acoustic mode different from each other, and the radiation elements of the first and second cells are arranged with a gap therebetween; In the design support process, a design support method for a radiated sound control structure is provided in which the provisionally determined configurations of the first and second cells are adjusted so that the radiating elements of the first and second cells are independent of each other and can excite the air in the radiation space in opposite phases to each other, in order to generate an interference effect between specific frequencies of the first and second cells to reduce the radiated sound.

8. In the design support step, when a and b are each an integer of 1 or more, the radiated sound control structure has a number of the first cells and b number of the second cells, and it is assumed that there are a first virtual structure in which the radiated sound control structure has been modified to have b number of the first cells instead of b number of the second cells, and a second virtual structure in which the radiated sound control structure has been modified to have a number of the second cells instead of a number of the first cells, in order to generate the interference action so as to most reduce the radiated sound at a predetermined intermediate frequency between the specific frequencies of the first and second cells, the value obtained by multiplying the average vibration volume velocity in the air in the radiation space excited by the first virtual structure by a is equal to the value obtained by multiplying the average vibration volume velocity in the air in the radiation space excited by the second virtual structure by b at the intermediate frequency. The design support method for a sound radiated control structure according to claim 7, wherein at least one of the shape, size, density, elastic modulus, and material of each of the provisionally determined first and second cells is adjusted so that the value obtained by multiplying the average vibration volume velocity in the air in the radiation space excited by the second virtual structure by b is equal to the value obtained by multiplying the average vibration volume velocity in the air in the radiation space excited by the second virtual structure by b at the intermediate frequency.

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