JP2010031582A - Sound absorbing structure, sound absorbing structure group, and acoustic room - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate and/or membrane type sound absorbing structure enhancing the strength of a bottom part of a case in particular. <P>SOLUTION: Ribs 25 are formed at a bottom plate 21 of the case 20 by combining a plurality of plate bodies 26 in grated shape. The ribs 25 provide the bottom plate 21 with strength, and spaces partitioned by plate bodies 26 of the ribs 25 serve as cells 41 for dividing an air layer 40. In comparison with a sound absorbing structure with no rib 25, this sound absorbing structure obtains effects of (1) lowering a sound absorbing frequency f0 to a sound absorbing frequency f0', (2) enlarging a sound absorbing frequency band Δf to a sound absorbing frequency band Δf' and (3) raising acoustic absorptivity α0 to acoustic absorptivity α0'. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sound absorbing structure that absorbs sound, a sound absorbing structure group, and an acoustic chamber.

The sound absorbing structure includes a housing having a bottom and an opening, and a plate-like or membrane-like vibrating body provided in the opening and defining an air layer in the housing (plate / membrane). There is a vibration type sound absorbing structure (Patent Document 1). In this type of sound absorbing structure, a spring mass system is formed by the mass component of the vibrating body and the spring component of the air layer.
Here, the density of air is ρ ₀ [kg / m ³ ], the speed of sound is c ₀ [m / s], the density of the vibrating body is ρ [kg / m ³ ], the thickness of the vibrating body is t [m], Assuming that the thickness of the air layer is L [m], the resonance frequency f [Hz] of the spring mass system is expressed by Equation 1.

In addition, when the vibration body has elasticity in the sound absorbing structure, the bending property of the elastic vibration is added.
The shape of the vibrator is rectangular, the length of one side is a [m], the length of the other side is b [m], the Young's modulus of the vibrator is E [N / m ² ], and the Poisson's ratio of the vibrator is σ [ −], P and q are positive integers, the resonance frequency of the plate / membrane vibration type sound absorbing structure is obtained as shown in the following formula 2. In the field of architectural acoustics, the obtained resonance frequency is used for acoustic design (for example, see Non-Patent Document 2).

上記数式２において、共振周波数ｆは、バネマス系に係る項（ρ₀ｃ₀ ²／ρｔＬ）と屈曲系に係る項（バネマス系の項の後に直列に加えられている項）とを加算した値となっている。この数式２に示すように、吸音構造体においては、振動体のバネマス系と、弾性振動による屈曲系とが、吸音条件を決める重要な要素となっている。

In Equation 2, the resonance frequency f is a value obtained by adding a term related to the spring mass system (ρ ₀ c ₀ ² / ρtL) and a term related to the bending system (term added in series after the term of the spring mass system). It has become. As shown in Formula 2, in the sound absorbing structure, the spring mass system of the vibrating body and the bending system due to elastic vibration are important factors that determine the sound absorbing conditions.

JP 2006-11412 A Sho Kimura “Architectural Acoustics and Noise Prevention Project” Shokokusha Co., Ltd., February 20, 1981, p.150

  As described above, the sound absorption characteristic (resonance frequency f) of the sound absorbing structure depends on the spring mass system and elastic vibration of the vibrating body. For this reason, it is desirable that the member (housing) other than the vibrating body has a strength that does not cause elastic deformation or the like. In particular, if the bottom plate parallel to the vibrating body in the housing is elastically vibrated, this vibration is transmitted to the vibrating body through the air layer and affects the elastic deformation of the vibrating body. Therefore, securing the strength of the bottom plate is an important issue in maintaining the sound absorbing characteristics of the sound absorbing structure.

  Therefore, the present invention has been made under the background described above, and in the sound absorption structure of the plate / membrane vibration type, the sound absorption structure, the sound absorption structure group, and the acoustic chamber in which the strength of the bottom portion of the casing is increased. The purpose is to provide.

  The structure of the sound-absorbing structure employed by the present invention to solve the above-described problem is a casing having a bottom portion and an opening, and a plate-like shape provided in the opening and defining an air layer in the casing. And a rib is provided on the bottom of the casing.

  The said structure WHEREIN: It is desirable that the said rib consists of a several plate body extended toward the said opening part from the said bottom part.

  The said structure WHEREIN: It is desirable for the said rib to form a plate body in a grid | lattice form.

  In the above configuration, the rib is preferably formed by forming a plate in a honeycomb shape.

  In the above configuration, the rib is preferably formed by concentrically arranging a plurality of cylindrical bodies having different diameters.

  In the above-described configuration, it is desirable that the individual spaces partitioned by the ribs have different volumes depending on the positions of the opposed vibrating bodies.

  In the above configuration, it is preferable that the space is formed so that a volume of a space located at a central portion of the vibrating body is larger than a volume of another space.

  In the above configuration, it is desirable that the vibrating body is formed so that the concentrated mass is different at a site of the vibrating body.

  The structure of the sound absorbing structure group employed by the present invention to solve the above-described problems is characterized by combining a plurality of the above sound absorbing structures.

  In order to solve the above-described problems, the structure of the acoustic chamber employed by the present invention is characterized by having the above-described sound absorbing structure or the above-described sound absorbing structure group.

  According to the present invention, in the sound absorbing structure (plate / membrane vibration type), by forming a rib on the bottom, the strength of the bottom is increased without changing the sound absorbing condition of the sound absorbing structure, and the housing itself It is possible to reduce the weight.

<Configuration of sound absorbing structure>
FIG. 1 is an exploded perspective view of a sound absorbing structure 10 according to an embodiment of the present invention. In the drawings, the actual dimensions of the sound absorbing structure 10 are different from each other for easy understanding of the configuration of the present embodiment.
As shown in the figure, the sound absorbing structure 10 includes a housing 20 that forms the base of the sound absorbing structure 10, a vibrating body 30 that covers the opening 23 of the housing 20, and the vibration of the housing 20. And an air layer 40 defined in the housing 20 by the body 30.

  The casing 20 is formed of a synthetic resin (for example, ABS resin) in a rectangular and shallow bottomed cylindrical shape, and includes a bottom plate 21, a side wall 22, and an opening 23. The bottom plate 21 is disposed on a surface facing the opening 23, and the side wall 22 is disposed around the opening 23. The vibrating body 30 is formed in a square plate shape from an elastic polymer compound (for example, an olefin copolymer containing an inorganic filler), and the periphery thereof is bonded and fixed to the opening 23 of the housing 20. Inside the sound absorbing structure 10 (behind the vibrating body 30), the vibrating body 30 is fixed to the opening 23 of the housing 20, whereby a sealed air layer 40 is defined.

  In the present embodiment, the material of the vibrating body 30 is a synthetic resin. However, the material of the vibrating body 30 is not limited to a synthetic resin, and other materials such as paper, metal, and fiberboard may be used as long as they generate elastic vibration. It may be a material. The shape of the vibrating body 30 may be a film instead of a plate. In short, the vibrating body 30 is a shape / member that deforms when a force is applied and vibrates by generating a restoring force by elasticity. I just need it.

  Here, the plate shape is a shape having a relatively thin thickness and a two-dimensional extension with respect to a rectangular parallelepiped (solid), and the film shape (film shape, sheet shape) is more than the plate shape. It is relatively thin and generates a restoring force by tension.

Further, the vibrating body 30 has relatively low rigidity with respect to the casing 20 other than the vibrating body 30 (low Young's modulus, thin thickness, small cross-sectional second moment), or mechanical impedance (8 × (bending rigidity × surface density) ^1/2 ) is formed with a relatively low shape / member. That is, the vibrating body 30 exhibits the sound absorbing action of the sound absorbing structure 10 by the vibrating body 30 by facilitating elastic vibration with respect to the housing 20.

The above is the basic structure of the sound absorbing structure 10, but in the sound absorbing structure 10 according to the present embodiment, as shown in FIGS. 2 and 3, lattice-like ribs 25 are formed on the bottom plate 21 of the housing 20. Has been.
The ribs 25 are arranged by combining a plurality of plate bodies 26 erected from the bottom plate 21 toward the opening 23 in a lattice shape. The rib 25 gives the bottom plate 21 strength, and the space partitioned by the plate body 26 of the rib 25 becomes a cell 41 that divides the air layer 40. A gap 42 is formed between the rib 25 and the vibrating body 30 to prevent the vibrating body 30 from striking against the rib 25 when the vibrating body 30 vibrates. Each cell 41 is communicated via the gap 42. The

<Operation of sound absorbing structure>
In the sound absorbing structure 10 configured as described above, the vibrating body 30 is caused by the difference between the sound pressure applied from the outside of the vibrating body 30 and the sound pressure on the air layer 40 side (that is, the sound pressure difference before and after the vibrating body 30). Elastically vibrates. Thereby, the energy of the sound wave reaching the sound absorbing structure 10 is consumed by the vibration of the vibrating body 30 and the sound is absorbed. At this time, the vibrating body 30 absorbs a sound having a frequency centered on the resonance frequency f set as shown in Formula 2.

<Effect of sound absorbing structure in embodiment>
The effect of the sound absorbing structure in this embodiment will be described based on the characteristic diagram of FIG.
FIG. 4 is a characteristic diagram showing a characteristic line A (solid line) of the sound absorbing structure in which the rib 25 is not formed and a characteristic line B (two-dot chain line) of the sound absorbing structure in which the rib 25 is formed. Indicates the frequency, and the vertical axis indicates the sound absorption coefficient.
When the characteristic lines A and B are compared, (1) the frequency f0 indicating the peak of the sound absorption rate decreases to the same frequency f0 ′, and (2) the sound absorption frequency band (for example, a frequency band that is half the peak value of the sound absorption rate). Δf spreads over the same frequency band Δf ′, and (3) the effect that the peak value α0 of the sound absorption coefficient increases to the same peak value α0 ′ is obtained.

Hereinafter, the reason for the above effect will be described.
(1) Decrease in sound absorption frequency In the sound absorption structure 10 according to the present embodiment, a lattice-like rib 25 is formed on the bottom body 21, and the air layer 40 is divided into a plurality of cells 41 by the rib 25. The rib 25 has a shape in which rectangular thin tubes opened toward the vibrating body 30 by the plate body 26 are arranged on the bottom plate 21. For this reason, the air generated by the elastic vibration of the vibrating body 30 flows into each cell 41. Although the thickness of the casing 20 does not seem to change, the thickness of the air layer 40 in the direction perpendicular to the vibrating body is substantially increased (increased), and the sound absorbing structure 10 having the ribs 25 is obtained. Will decrease the sound absorption frequency f0.

(2) Expansion of sound absorption frequency band Each cell 41 exhibits a sound absorption characteristic by tube sound absorption that generates sound between the wall surface and air to generate friction. As a result, the sound absorbing structure 10 can also have a sound absorbing characteristic due to sound absorption by the plate body 26 corresponding to the tube wall surface in addition to the sound absorbing characteristic due to the elastic vibration of the vibrating body 30, and the sound absorption frequency bandwidth Δf. To spread.

(3) Increase in sound absorption coefficient α0 Since each cell 41 rectifies the air flow caused by vibration generated from the vibrating body 30 in a direction substantially orthogonal to the vibrating body 30, the operation of the air layer 40 as an air spring is limited. The peak of the sound absorption coefficient α0 can be increased. That is, the air flow in the air layer 40 compressed / expanded by the vibration of the vibrating body 30 also flows in the direction parallel to the vibrating body 30 when each cell 41 is not present. The flow is limited to a direction substantially orthogonal to the vibrating body 30. For this reason, the acoustic impedance Z of the air layer 40 can be fixed to a constant value that depends on the thickness L of the back air layer, and the peak of the sound absorption coefficient α0 at the resonance frequency is prevented from being lowered.

  On the other hand, since the sound absorbing structure 10 has the lattice-like ribs 25 formed from the plate bodies 26 erected from the bottom plate 21, the strength (bending rigidity) of the bottom plate 21 compared to the case where the ribs 25 are not formed. Can be increased. As a result, compared with the case where the rib 25 is not formed, the thickness of the bottom plate 21 can be reduced, and the weight of the sound absorbing structure 10 can be reduced.

<Modification>
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows.
<Modification 1>
In the above-described embodiment, the case where the ribs 25 are formed in a lattice shape by the plate bodies 26 is illustrated, but the present invention is not limited to this, and various rib shapes can be used.
FIG. 5 shows a cross-sectional view of a sound absorbing structure of a plate body 26A in which ribs 25A are formed obliquely from the bottom plate 21 in a slit shape. Cells 41A that divide the air layer 40 into slits are formed between the plate bodies 26A. 6 is a longitudinal sectional view as seen from the direction of arrows VI-VI in FIG. The rib 25 </ b> A is formed by a plate body 26 </ b> A that stands upright from the bottom plate 21. Thereby, the length of a slit is ensured long compared with embodiment.

  FIG. 7 shows a cross-sectional view of a sound absorbing structure of a plate body 26B in which ribs 25B are formed in a honeycomb shape from the bottom plate 21. FIG. Cells 41B that divide the air layer 40 into hexagonal shapes are formed between the plate bodies 26B. The honeycomb-like ribs 25 </ b> B have a height direction strength higher than that of the lattice-like ribs 25 and can enhance the rectifying action.

FIG. 8 shows a cross-sectional view of a sound absorbing structure in which a rib 25C in which a plurality of cylindrical bodies 26C, 26C,... Having different diameters are arranged concentrically is formed. A cell 41C that divides the air layer 40 into an annular shape is formed between the cylinders 26C.
Further, the cylindrical body constituting the concentric rib 25C may have a cylindrical body 26C2 shown in FIG. 9B, even if the cylindrical body extends in the vertical direction like the cylindrical body 26C1 shown in FIG. Even in the case of a truncated cone shape (conical shape with a flat top), the height of the cylinder arranged from the outside to the inside as in the cylinder 26C3 shown in FIG. It may be a cylindrical body formed sequentially lower.
As shown in FIG. 9C, the reason why the height of the cylindrical body is lowered as it goes toward the center of the vibrating body 30 is that the portion whose amplitude increases when the vibrating body 30 vibrates hits the cylindrical body. This is to prevent this.

FIG. 10 shows a sound absorbing structure in which ribs 25D are formed so that the interval between the plate bodies 26D arranged in a lattice shape is such that the position facing the center of the vibrating body 30 is large and spreads outward. A cross-sectional view is shown. A cell 41D that divides the air layer 40 is formed between the plate bodies 26D, and the volume of the cell 41D that faces the central portion of the vibrating body 30 is large and decreases as it spreads outward.
Thus, by varying the volume of the cell 41D according to the position of the vibrating body 30, the constant of the air spring is increased where the amplitude of the vibrating body 30 is large, and the constant of the air spring is decreased where the amplitude is small. The elastic vibration of the vibrating body 30 can be efficiently absorbed by the air layer 40.

  9C shows the case where the height of the truncated cone-shaped cylindrical body 26C3 decreases toward the center of the vibrating body 30, the lattice-shaped plate body 26 shown in FIG. In FIG. 6, the slit plate 26 </ b> A shown in FIG. 6 is formed at the center of the vibrating body 30 even if the opposing plate 26 is formed so that the height thereof decreases toward the center of the vibrating body 30. Even if the opposing plate body 26A is formed to have a lower height as it goes, in the honeycomb-like plate body 26B shown in FIG. Even if the height of the plate 26D shown in FIG. 11 is changed, the height of the cylinder 26C1 extending in the vertical direction as shown in FIG. Follow the direction toward the center of the vibrating body 30 It may be formed so as to reduce the height of the plate member 26D to the opposite.

<Modification 2>
In the sound absorbing structure configured as described above, the relationship between the resonance frequency of the spring mass system and the resonance frequency of the bending system due to the elastic vibration due to the elasticity of the plate is uniquely determined by Equation 2, but actually In fact, the structure of a sound-absorbing structure that exhibits high sound-absorbing power in the low sound range has not been established.

Therefore, the inventors conducted intensive experiments, and as a result, when the value of the fundamental vibration frequency of the bending system is fa and the value of the resonance frequency of the spring mass system is fb, the above parameters are satisfied so as to satisfy the relationship of Equation 3 below. Set. As a result, the fundamental vibration of the bending system is coupled with the spring component of the air layer behind, and a vibration having a large amplitude is excited in the band between the resonance frequency of the spring mass system and the fundamental frequency of the bending system (the bending system). The fact that the resonance frequency fa <the sound absorption peak frequency f <the spring mass system fundamental frequency fb) and the sound absorption rate is high was verified.

このように、上記した数式３，４の条件を満足するように各種パラメータを設定することにより、吸音のピークとなる周波数を低くした吸音構造体が構成できる。 Furthermore, when the following Expression 4 is set, the frequency of the sound absorption peak is sufficiently smaller than the resonance frequency of the spring mass system. In this case, it was also verified that the fundamental frequency of the bending system is sufficiently smaller than the resonance frequency of the spring mass system due to the mode of low-order elastic vibration, and is suitable as a sound absorbing structure that absorbs sound having a frequency of 300 [Hz] or less.

As described above, by setting various parameters so as to satisfy the conditions of the above-described Expressions 3 and 4, it is possible to configure a sound absorbing structure in which the frequency at which the sound absorption is peaked is lowered.

<Modification 3>
Furthermore, the configuration of the sound absorbing structure 10 includes a rectangular casing 20, a vibrating body 30 that closes the opening 23 of the casing 20, and an air layer 40 defined in the casing 20. However, the shape of the housing according to the present invention is not limited to a rectangular shape, and may be a circular shape or a polygonal shape.
Further, a concentrated mass for changing the vibration condition with respect to the vibrating body 30 may be provided in the central portion of the vibrating body 30.

  As described above, the sound absorbing structure 10 has a sound absorbing mechanism formed of a spring mass system and a bending system. Here, the inventors conducted an experiment of the sound absorption coefficient at the resonance frequency when the surface density of the vibrating body 30 was changed.

  FIG. 12 shows that a vibrating body 30 (size: 100 mm × 100 mm, thickness: 0.85 mm) is fixed to a casing 20 having a vertical and horizontal size of 100 mm × 100 mm and a thickness of 10 mm. It is the figure which showed the simulation result of the normal incidence sound absorption coefficient of the sound-absorbing structure 10 at the time of changing the surface density of a part (a magnitude | size is 20 mm x 20 mm, thickness 0.85mm). In addition, the simulation method is based on JIS A 1405-2 (measurement of sound absorption coefficient and impedance by an acoustic tube—Part 2: transfer function method), and the sound field of the acoustic room in which the sound absorbing structure 10 is arranged is determined by a finite element method. The sound absorption characteristics were calculated from the transfer function.

Specifically, the surface density of the central part is (1) 399.5 [g / m ² ], (2) 799 [g / m ² ], (3) 1199 [g / m ² ], (4) 1598 [g / m ² ], (5) 2297 [g / m ² ], the surface density of the peripheral member is 799 [g / m ² ], and the average density of the vibrating body 30 is (1) 783 [g / m ² ]. m ² ], (2) 799 [g / m ² ], (3) 815 [g / m ² ], (4) 831 [g / m ² ], (5) 863 [g / m ² ] This is a simulation result.
Looking at the simulation results, the sound absorption rate is high between 300 and 500 [Hz] and in the vicinity of 700 [Hz].

  The high sound absorption rate near 700 [Hz] is due to resonance of the spring mass system formed by the mass of the vibrating body 30 and the spring component of the air layer 40. In the sound absorbing structure 10, the sound is absorbed with the sound absorption coefficient at the resonance frequency of the spring mass system as a peak, and even if the surface density of the central portion is increased, the mass of the entire vibrating body 30 does not change greatly. It can be seen that the resonance frequency does not change significantly.

  Further, the sound absorption coefficient between 300 and 500 [Hz] is high due to the resonance of the bending system formed by the bending vibration of the vibrating body 30. In the sound absorbing structure 10, the sound absorption rate at the resonance frequency of the bending system appears as a peak on the low frequency range side, and only the resonance frequency of the bending system decreases as the surface density at the center increases. I understand.

  In general, the resonance frequency of the bending system is determined by an equation of motion governing the elastic vibration of the vibrating body 30 and is inversely proportional to the density (surface density) of the vibrating body 30. The resonance frequency is greatly influenced by the density of the antinodes of natural vibration (when the amplitude is a maximum value). For this reason, in the simulation described above, the region that becomes the antinode of the 1 × 1 eigenmode is formed at different surface densities in the central portion, so that the resonance frequency of the bending system is changed.

  Thus, the simulation results show that when the surface density of the central part is made larger than the surface density of the peripheral part, the peak of the sound absorption coefficient on the low frequency side of the frequency that becomes the peak of sound absorption moves further to the low frequency side. Represents. Therefore, it is shown that by changing the surface density of the central portion, a part of the frequency at which the sound absorption is peaked can be moved (shifted) further to the low sound region side or the high sound region side.

  In the sound absorbing structure 10 described above, since the frequency of the peak of the sound to be absorbed can be changed (shifted) simply by changing the surface density of the central portion, the vibration body 30 is made of the same material as the entire sound absorbing structure 10. Compared with the case where the sound absorption sound is changed by increasing the mass of the entire sound absorbing structure 10 and changing the sound absorbing sound, the sound to be absorbed can be lowered without greatly changing the mass of the entire sound absorbing structure 10.

<Modification 4>
Moreover, the sound absorption coefficient peak value may be increased by filling the air layer 40 of the sound absorbing structure 10 with a porous sound absorbing material (for example, cotton-like fibers such as foamed resin, felt, polyester wool). .

<Modification 5>
Furthermore, by adhering a friction material (for example, a member having resistance to air vibration caused by sound waves, such as a thin fabric) to the surface of the plate body 26, the sound absorbing force of the sound absorbing structure 10 is further increased. Is possible.

<Modification 6>
Further, in the present invention, when the sound absorbing structure group is formed, not only the sound absorbing structure group is formed by combining a plurality of sound absorbing structures of any one of the above-described embodiments or modifications, but for example, a sound absorbing characteristic Sound absorbing structures having different sound absorbing characteristics may be combined to form a sound absorbing structure group, such as combining sound absorbing structures having different sound absorption characteristics, or combining sound absorbing structures having three or more different sound absorbing characteristics.

  Further, the sound absorbing structure according to the present invention and the sound absorbing structure group obtained by combining the sound absorbing structures can be disposed in various acoustic chambers that control acoustic characteristics. Here, the various acoustic rooms include soundproof rooms, halls, theaters, listening rooms for audio equipment, living rooms such as conference rooms, spaces for various transport equipment such as vehicles, and housings for speakers and musical instruments.

It is a disassembled perspective view of the sound absorption structure by embodiment. It is the cross-sectional view seen from the arrow II-II direction of FIG. It is the longitudinal cross-sectional view seen from the arrow III-III direction of FIG. It is a characteristic diagram which shows the characteristic by the sound-absorbing structure by embodiment. It is a cross-sectional view of a sound absorbing structure according to modification (1). It is the longitudinal cross-sectional view seen from the arrow VI-VI direction of FIG. It is a cross-sectional view which shows the other structure of the sound-absorbing structure by a modification (1). It is a cross-sectional view which shows the other structure of the sound-absorbing structure by a modification (1). It is a longitudinal cross-sectional view corresponding to the sound absorption structure shown in FIG. It is a cross-sectional view which shows another structure of the sound-absorbing structure by a modification (1). It is the longitudinal cross-sectional view seen from the arrow XI-XI direction of FIG. It is a characteristic diagram which shows the characteristic by a modification (3).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sound absorption structure, 20 ... Housing, 21 ... Bottom plate, 22 ... Side wall, 23 ... Opening, 25, 25A, 25B, 25C, 25D ... Rib, 26, 26A, 26B, 26D ... plate body, 26C ... cylindrical body, 30 ... vibrating body, 40 ... air layer, 41, 41A, 41B, 41C, 41D ... cell

Claims (10)

A housing having a bottom and an opening;
A plate-like or membrane-like vibrating body provided in the opening and defining an air layer in the housing;
A sound absorbing structure, wherein a rib is provided at a bottom of the casing. The sound absorbing structure according to claim 1,
The rib is composed of a plurality of plates extending from the bottom toward the opening. The sound absorbing structure according to claim 1 or 2,
The rib is formed by forming a plate in a lattice shape. The sound absorbing structure according to claim 1 or 2,
The rib is formed by forming a plate body in a honeycomb shape. The sound absorbing structure according to claim 1 or 2,
The rib is formed by concentrically arranging a plurality of cylindrical bodies having different diameter dimensions. In the sound-absorbing structure according to any one of claims 1 to 5,
The volume of each space divided by the rib differs depending on the position of the opposing vibrating body. The sound absorbing structure according to claim 6, wherein
The sound absorbing structure, wherein the space is formed such that a volume of a space located at a central portion of the vibrating body is larger than a volume of another space. The sound-absorbing structure according to any one of claims 1 to 7,
The sound absorbing structure according to claim 1, wherein the vibrating body is formed so as to have different concentrated masses at a portion of the vibrating body. A sound-absorbing structure group comprising a plurality of sound-absorbing structures according to any one of claims 1 to 8. An acoustic chamber comprising the sound absorbing structure according to any one of claims 1 to 8, or the sound absorbing structure group according to claim 9.

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