JP2010097147A - Sound absorbing structure, sound absorbing structure group and acoustic room - Google Patents

Sound absorbing structure, sound absorbing structure group and acoustic room Download PDF

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JP2010097147A
JP2010097147A JP2008270325A JP2008270325A JP2010097147A JP 2010097147 A JP2010097147 A JP 2010097147A JP 2008270325 A JP2008270325 A JP 2008270325A JP 2008270325 A JP2008270325 A JP 2008270325A JP 2010097147 A JP2010097147 A JP 2010097147A
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sound absorbing
absorbing structure
region
sound
closing member
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JP2010097147A5 (en
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Yasuhito Tanase
廉人 棚瀬
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Yamaha Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To improve sound absorbing efficiency with a simple structure, in a case where a Helmholtz resonator and a plate-film vibration sound absorbing structure are combined. <P>SOLUTION: The sound absorbing structure 10 includes a case 11 and a closing member 12. The case 11 includes a hollow region and its aperture section is closed by a closing member 12. The case 11 includes a partition wall for partitioning the hollow section, and in the figure, the hollow section is divided into a first region of a circle shape, and a second section other than the first region. The closing member 12 is a vibrating plate shape or film shape member, and a hole section is provided at a position facing the second region. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、吸音する技術に関する。   The present invention relates to a technique for absorbing sound.

板振動又は膜振動をする吸音構造が知られている。かかる吸音構造のことを、以下では「板・膜振動吸音構造」という。また、吸音効率の向上を目的に、板・膜振動吸音構造とヘルムホルツ共鳴器（レゾネータ）とを組み合わせる技術が知られている（例えば、特許文献１参照）。
特開平１１−３３８４７６号公報（図１、図４等） Sound absorbing structures that perform plate vibration or membrane vibration are known. Such a sound absorbing structure is hereinafter referred to as a “plate / membrane vibration absorbing structure”. In addition, for the purpose of improving sound absorption efficiency, a technique for combining a plate / membrane vibration absorption structure and a Helmholtz resonator (resonator) is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 11-338476 (FIG. 1, FIG. 4 etc.)

特許文献１に記載された技術は、ヘルムホルツ共鳴器の構成を変更すると板・膜振動吸音構造の吸音特性が変化してしまうため、両者を組み合わせた全体としての吸音特性の設計が複雑となる。また、特許文献１の図４に記載された技術は、ヘルムホルツ共鳴器として機能させるための開口部を板・膜振動吸音構造の振動部分に設けたものであるため、その開口部により振動部分の内外の音圧差が低減され、板・膜振動吸音構造による吸音の効率が低下するものである。
そこで、本発明は、ヘルムホルツ共鳴器と板・膜振動吸音構造とを組み合わせて設ける場合において、吸音効率の向上を簡便な構成で実現することを目的とする。 In the technique described in Patent Document 1, if the configuration of the Helmholtz resonator is changed, the sound absorption characteristic of the plate / membrane vibration absorption structure is changed, so that the design of the sound absorption characteristic as a whole combining both is complicated. In the technique described in FIG. 4 of Patent Document 1, an opening for functioning as a Helmholtz resonator is provided in the vibration part of the plate / membrane vibration absorption structure. The sound pressure difference between the inside and outside is reduced, and the efficiency of sound absorption by the plate / membrane vibration absorption structure is reduced.
Accordingly, an object of the present invention is to realize an improvement in sound absorption efficiency with a simple configuration when a Helmholtz resonator and a plate / membrane vibration absorption structure are provided in combination.

本発明に係る吸音構造は、開口した中空領域を第１領域と第２領域とに隔てる隔壁を有する筐体と、板状又は膜状であり、前記筐体に支持されて前記中空領域の開口部を塞ぐ閉塞部材とを備え、前記閉塞部材が、前記第２領域に面する位置に孔部を有する構成を特徴とする。なお、かかる構成において、筐体内の中空領域は、第１領域又は第２領域以外の領域を含むことを妨げないが、第１領域及び第２領域のみで構成されていると、より望ましい。
本発明に係る吸音構造は、前記閉塞部材の前記第１領域に面する面積が前記第２領域に面する面積より大である構成であってもよい。
本発明に係る吸音構造は、前記第２領域の容積が前記第１領域の容積より小である構成であってもよい。
本発明に係る吸音構造は、前記第２領域から外部に向かって開口する筒状部材を前記孔部に備える構成であってもよい。
本発明に係る吸音構造は、前記第２領域及び前記筒状部材を複数備え、複数の前記筒状部材は、その長さ及び断面積の少なくともいずれかが互いに同一でない構成であってもよい。
本発明に係る吸音構造は、前記隔壁が、前記第１領域を複数形成するとともに、前記第２領域を複数の前記第１領域の間隙に形成する構成であってもよい。
本発明に係る吸音構造群は、前記吸音構造のいずれかを組み合わせて備えることを特徴とする。なお、かかる構成において、吸音構造の組み合わせは、同種の吸音構造を組み合わせるものであってもよいし、異種の吸音構造を組み合わせるものであってもよい。
本発明に係る吸音構造群は、複数の前記吸音構造の前記第２領域の容積及び前記孔部の面積の少なくともいずれかが互いに同一でない構成であってもよい。
本発明に係る吸音構造群は、複数の前記吸音構造が一の板状又は膜状の部材により前記閉塞部材を構成するものであってもよい。
本発明に係る音響室は、上述した吸音構造又は吸音構造群を備えることを特徴とする。 The sound absorbing structure according to the present invention includes a housing having a partition wall that separates an open hollow region into a first region and a second region, and a plate shape or a film shape, and is supported by the housing to open the hollow region. A closing member that closes the portion, and the closing member has a hole at a position facing the second region. In this configuration, the hollow region in the housing does not prevent the region other than the first region or the second region from being included, but it is more preferable that the hollow region is configured only by the first region and the second region.
The sound absorbing structure according to the present invention may be configured such that an area facing the first region of the blocking member is larger than an area facing the second region.
The sound absorbing structure according to the present invention may be configured such that the volume of the second region is smaller than the volume of the first region.
The sound absorbing structure according to the present invention may have a configuration in which the hole portion includes a cylindrical member that opens from the second region toward the outside.
The sound absorbing structure according to the present invention may include a plurality of the second region and the cylindrical member, and the plurality of cylindrical members may be configured such that at least one of the length and the cross-sectional area thereof is not the same.
The sound absorbing structure according to the present invention may be configured such that the partition wall forms a plurality of the first regions and the second region is formed in a gap between the plurality of first regions.
The sound absorbing structure group according to the present invention includes any one of the sound absorbing structures. In this configuration, the combination of the sound absorbing structures may be a combination of the same kind of sound absorbing structures or a combination of different kinds of sound absorbing structures.
The sound absorbing structure group according to the present invention may be configured such that at least one of the volume of the second region and the area of the hole portion of the plurality of sound absorbing structures is not the same.
The sound absorbing structure group according to the present invention may be configured such that a plurality of the sound absorbing structures constitutes the closing member by a single plate-like or film-like member.
The acoustic chamber according to the present invention includes the above-described sound absorbing structure or sound absorbing structure group.

本発明によれば、ヘルムホルツ共鳴器と板・膜振動吸音構造とを組み合わせて設ける場合において、吸音効率の向上を簡便な構成で実現させることが可能となる。   According to the present invention, when a Helmholtz resonator and a plate / membrane vibration absorption structure are provided in combination, it is possible to improve the sound absorption efficiency with a simple configuration.

［実施形態］
図１は、本発明の一実施形態である吸音構造の構成を示す図である。この吸音構造１０は、直方体状の形状を有し、筐体１１と閉塞部材１２とを備える。筐体１１は、吸音構造１０の側面及び底面を構成するとともに、破線で示す隔壁を内部に有する。閉塞部材１２は、吸音構造１０の上面を構成し、所定の位置に孔部を有する。なお、ここでいう「上面」は、面の方向を便宜的に表したものであって、吸音構造１０が配置されるときに上方向を向くことを表したものではない。吸音構造１０は、その配置に際しては、必要に応じてどのような向きで配置されてもよい。 [Embodiment]
FIG. 1 is a diagram showing a configuration of a sound absorbing structure according to an embodiment of the present invention. The sound absorbing structure 10 has a rectangular parallelepiped shape and includes a housing 11 and a closing member 12. The casing 11 constitutes the side surface and the bottom surface of the sound absorbing structure 10 and has a partition wall indicated by a broken line inside. The closing member 12 constitutes the upper surface of the sound absorbing structure 10 and has a hole at a predetermined position. The “upper surface” here represents the direction of the surface for the sake of convenience, and does not represent the upward direction when the sound absorbing structure 10 is arranged. The sound absorbing structure 10 may be arranged in any orientation as necessary.

筐体１１は、振動体として機能する閉塞部材１２を支持する部材である。筐体１１は、例えば、ＡＢＳ樹脂等の合成樹脂により形成されているが、閉塞部材１２を支持可能な強度を有するものであれば、金属など他の材料であってもよい。筐体１１は、側面を構成する部分と、底面を構成する部分と、隔壁を構成する部分とに分類される。以下においては、これらの各部を、それぞれ「側面部」、「底面部」、「隔壁部」という。筐体１１は、これらが一体成形されたものであってもよいし、独立した各部を接着等により固定したものであってもよい。   The housing 11 is a member that supports the closing member 12 that functions as a vibrating body. The housing 11 is made of, for example, a synthetic resin such as ABS resin, but may be made of other materials such as metal as long as it has a strength capable of supporting the closing member 12. The casing 11 is classified into a part constituting a side surface, a part constituting a bottom surface, and a part constituting a partition wall. Hereinafter, these parts are referred to as “side part”, “bottom part”, and “partition part”, respectively. The housing 11 may be one in which these are integrally molded, or may be one in which independent parts are fixed by bonding or the like.

図２は、筐体１１を図１中のＡ−Ａ線で切断した場合の断面図である。同図に示すように、筐体１１は、隔壁部１１１、側面部１１２及び底面部１１３を有する。隔壁部１１１は、中空である円筒状の部材を複数連結したような形状を有する。隔壁部１１１において、各々の円筒は、その円の中心と隣り合う円筒の中心とを結んだとき、結んだ線分が側面と平行（又は垂直）になるように並んでいる。また、側面部１１２及び底面部１１３は、板状である。本実施形態においては、底面部１１３が正方形であり、側面部１１２の各面が長方形であるとする。   2 is a cross-sectional view of the housing 11 taken along line AA in FIG. As shown in the figure, the housing 11 has a partition wall 111, a side surface 112, and a bottom surface 113. The partition wall 111 has a shape in which a plurality of hollow cylindrical members are connected. In the partition wall 111, each cylinder is arranged so that the connected line segment is parallel (or perpendicular) to the side surface when the center of the circle is connected to the center of the adjacent cylinder. Further, the side surface portion 112 and the bottom surface portion 113 are plate-shaped. In the present embodiment, it is assumed that the bottom surface portion 113 is square and each surface of the side surface portion 112 is rectangular.

隔壁部１１１は、閉塞部材１２、側面部１１２及び底面部１１３により囲まれる中空領域を隔てることにより、これを複数の中空領域に分割する。各々の中空領域は、上面側と底面側において開口しており、それぞれの開口部が底面部１１３又は閉塞部材１２により塞がれている。隔壁部１１１が形成する中空領域は、中空領域ｈ1と中空領域ｈ2の２種類に分類される。中空領域ｈ1は、上述した円筒の内部に相当する円柱状の領域であり、中空領域ｈ2は、複数の円筒により囲まれた略四角柱状の領域である。
なお、筐体１１は、中空領域ｈ1及びｈ2のほかに、隔壁部１１１と側面部１１２により形成される中空領域ｈ3を形成する。中空領域ｈ3は、上述した円筒と側面部１１２により囲まれた略三角柱状の領域である。中空領域ｈ3は、中空領域ｈ2を半分又は１／４に分割した形状を有する。 The partition wall 111 divides the hollow area surrounded by the closing member 12, the side surface part 112, and the bottom surface part 113 into a plurality of hollow areas. Each hollow region is open on the upper surface side and the bottom surface side, and each opening portion is closed by the bottom surface portion 113 or the closing member 12. The hollow region formed by the partition wall 111 is classified into two types, a hollow region h 1 and a hollow region h 2 . The hollow region h 1 is a columnar region corresponding to the inside of the cylinder described above, and the hollow region h 2 is a substantially quadrangular columnar region surrounded by a plurality of cylinders.
The housing 11 forms a hollow region h 3 formed by the partition wall portion 111 and the side surface portion 112 in addition to the hollow regions h 1 and h 2 . Hollow region h 3 is a substantially triangular prism-shaped area surrounded by the cylinder and the side surface portion 112 as described above. The hollow region h 3 has a shape obtained by dividing the hollow region h 2 into half or ¼.

中空領域ｈ1及びｈ2のそれぞれの底面積は、隔壁部１１１の厚みをないものとみなし、上述した円柱の半径をｒ、円周率をπとした場合、次のＳ1（中空領域ｈ1の底面積）及びＳ2（中空領域ｈ2の底面積）で表される。
Ｓ1＝πｒ２
Ｓ2＝４×（ｒ２−πｒ２／４）＝（４−π）ｒ２
すなわち、中空領域ｈ1の底面積Ｓ1は、中空領域ｈ2の底面積Ｓ2より大である。また、本実施形態においては、隔壁部１１１及び側面部１１２の高さ（上面から底面までの距離）が一定であり、底面積と上面の面積が同一であるから、中空領域ｈ1及びｈ2の容積比は、その底面積の比に一致する。 The respective bottom areas of the hollow regions h 1 and h 2 are regarded as having no thickness of the partition wall 111, and when the radius of the above-described cylinder is r and the circumferential ratio is π, the following S 1 (hollow region h 1 ) and S 2 (the bottom area of the hollow region h 2 ).
S 1 = πr 2
S 2 = 4 × (r 2 -πr 2/4) = (4-π) r 2
That is, the bottom surface area S 1 of the hollow area h 1 is greater than the bottom surface area S 2 of the hollow region h 2. In the present embodiment, the height (distance from the top surface to the bottom surface) of the partition wall portion 111 and the side surface portion 112 is constant, and the bottom area and the top surface area are the same, so that the hollow regions h 1 and h 2 are the same. The volume ratio corresponds to the ratio of its bottom area.

閉塞部材１２は、中空領域ｈ1、ｈ2及びｈ3の上面側の開口部を塞ぐ板状又は膜状の部材である。閉塞部材１２は、板状又は膜状の部材であるが、その厚さは特に問わない。閉塞部材１２は、例えば、合成樹脂により形成されているが、筐体１１に支持されて振動する程度の弾性を有するものであれば、紙、金属、繊維など他の材料であってもよい。閉塞部材１２は、接着剤や釘などにより筐体１１に取り付けられている。 Closure member 12 is a plate-shaped or film-shaped member to close the opening of the upper surface side of the hollow area h 1, h 2 and h 3. The blocking member 12 is a plate-like or film-like member, but the thickness is not particularly limited. The closing member 12 is made of, for example, a synthetic resin, but may be made of other materials such as paper, metal, fiber, etc. as long as the closing member 12 is elastic enough to be supported by the housing 11 and vibrate. The closing member 12 is attached to the housing 11 with an adhesive or a nail.

図３は、筐体１１及び閉塞部材１２を図１中のＢ−Ｂ線で切断した場合の断面図である。同図に示すように、閉塞部材１２は、中空領域ｈ2及びｈ3に面する位置、すなわち中空領域ｈ2及びｈ3の上面側の開口部に相当する位置に孔部１２ａが設けられている。なお、孔部１２ａは、本実施形態においては円孔であるが、その形状は円形に限らず、また、サイズ（面積）も必要に応じて決めてよい。 3 is a cross-sectional view of the housing 11 and the closing member 12 taken along the line BB in FIG. As shown in the figure, the closing member 12 is located facing the hollow region h 2 and h 3, that is, the hole 12a is provided at a position corresponding to the opening of the upper surface of the hollow region h 2 and h 3 Yes. In addition, although the hole 12a is a circular hole in this embodiment, the shape is not limited to a circle, and the size (area) may be determined as necessary.

吸音構造１０の構成は、以上のとおりである。吸音構造１０は、この構成のもと、その内部、すなわち中空領域に気体が充填される。中空領域に充填される気体は、典型的には空気であり、本実施形態においても空気であるとするが、その他の気体であることを妨げない。この気体は、閉塞部材１２に対向する気体層（空気層）を形成する。   The structure of the sound absorbing structure 10 is as described above. With this configuration, the sound absorbing structure 10 is filled with gas inside, that is, in a hollow region. The gas filled in the hollow region is typically air, and it is assumed that it is also air in this embodiment, but it does not prevent other gases. This gas forms a gas layer (air layer) facing the closing member 12.

吸音構造１０は、中空領域ｈ1に対応する部分が板・膜振動吸音構造として機能する。すなわち、中空領域ｈ1の気体層は、いわゆる気体バネ（空気バネ）として機能する。具体的には、吸音構造１０にある音波が入射した場合に、閉塞部材１２のうちの中空領域ｈ1に対向する部分が振動体として機能して振動するとともに、この振動により気体層にも音波が入射して、気体層の音響エネルギーが増加する。この音響エネルギーは、閉塞部材１２の振動と、中空領域ｈ1の気体層の気体バネとしての作用と、閉塞部材１２と気体層などの内部抵抗による振動を減衰させる作用とにより減衰し、やがて消散する。すなわち、吸音構造１０は、閉塞部材１２の中空領域ｈ1に面する部分を質量成分（マス）とし、中空領域ｈ1の気体層をバネ成分としたバネマス系を形成する。 In the sound absorbing structure 10, a portion corresponding to the hollow region h 1 functions as a plate / membrane vibration sound absorbing structure. That is, the gas layer in the hollow region h 1 functions as a so-called gas spring (air spring). Specifically, when a sound wave in the sound absorbing structure 10 is incident, a portion of the closing member 12 facing the hollow region h 1 functions as a vibrating body and vibrates, and the vibration causes sound waves to the gas layer. Is incident and the acoustic energy of the gas layer increases. This acoustic energy is attenuated by the vibration of the closing member 12, the action of the gas layer in the hollow region h 1 as a gas spring, and the action of attenuating the vibration due to the internal resistance of the closing member 12 and the gas layer, and eventually dissipates. To do. That is, the sound absorbing structure 10 forms a spring mass system in which the portion facing the hollow region h 1 of the closing member 12 is a mass component (mass) and the gas layer of the hollow region h 1 is a spring component.

本実施形態の吸音構造１０の各部は、以下の条件により設定される。
一般に、板状又は膜状の振動体と気体層とにより音を吸収する板・膜振動吸音構造において、吸音する周波数は、振動体の質量成分と気体層のバネ成分とによるバネマス系の共振周波数によって設定される。ここで、気体層の気体の密度をρ0（ｋｇ／ｍ3）、音速をｃ0（ｍ／ｓ）、振動体の密度をρ（ｋｇ／ｍ3）、振動体の厚さをｔ（ｍ）、気体層の厚さをＬ（ｍ）とすると、バネマス系の共振周波数は以下の式（１）で表される。

Figure 2010097147
Each part of the sound absorbing structure 10 of this embodiment is set according to the following conditions.
In general, in a plate / membrane vibration absorbing structure that absorbs sound by a plate-like or membrane-like vibrating body and a gas layer, the sound absorbing frequency is the resonance frequency of the spring mass system due to the mass component of the vibrating body and the spring component of the gas layer. Set by Here, the density of the gas in the gas layer is ρ 0 (kg / m 3 ), the speed of sound is c 0 (m / s), the density of the vibrator is ρ (kg / m 3 ), and the thickness of the vibrator is t ( m) When the thickness of the gas layer is L (m), the resonance frequency of the spring mass system is expressed by the following equation (1).
Figure 2010097147

また、板・膜振動型吸音構造において、振動体が弾性を有して弾性振動をする場合には、弾性振動による屈曲系の性質が加わる。建築音響の分野においては、長方形である振動体の対向する二辺の長さをａ（ｍ）、当該二辺と直交する二辺の長さをｂ（ｍ）、振動体のヤング率をＥ（Ｐａ）、振動体のポアソン比をσ、モード次数をｐ及びｑ（正の整数）とすると、以下の式（２）で板・膜振動型吸音構造の共振周波数を求め、求めた共振周波数を音響設計に利用することが行われている（周辺支持の場合）。

Figure 2010097147
Further, in the plate / membrane vibration type sound absorbing structure, when the vibrating body has elasticity and elastically vibrates, a bending system property due to elastic vibration is added. In the field of architectural acoustics, the length of two opposing sides of a rectangular vibrating body is a (m), the length of two sides orthogonal to the two sides is b (m), and the Young's modulus of the vibrating body is E (Pa), where the Poisson's ratio of the vibrating body is σ and the mode orders are p and q (positive integers), the resonance frequency of the plate / membrane vibration type sound absorbing structure is obtained by the following equation (2), and the obtained resonance frequency Is used for acoustic design (in the case of peripheral support).
Figure 2010097147

本実施形態においては、１６０〜３１５Ｈｚバンド（１/３オクターブ中心周波数）を吸音するように、例えば、式（２）に基づいて以下のようにパラメータが設定される。
気体の密度ρ0 ：１．２２５（ｋｇ／ｍ3）
音速ｃ0 ：３４０（ｍ／ｓ）
振動体の密度ρ ：９４０（ｋｇ／ｍ3）
振動体の厚さｔ ：０．００１７（ｍ）
気体層の厚さＬ ：０．０３（ｍ）
筐体の長さａ ：０．１（ｍ）
筐体の長さｂ ：０．１（ｍ）
振動体のヤング率Ｅ：１．０（ＧＰａ）
ポアソン比σ ：０．４
モード次数 ：ｐ＝ｑ＝１ In the present embodiment, for example, parameters are set as follows based on Expression (2) so as to absorb the 160 to 315 Hz band (1/3 octave center frequency).
Gas density ρ 0 : 1.225 (kg / m 3 )
Speed of sound c 0 : 340 (m / s)
Density of vibrating body ρ: 940 (kg / m 3 )
Thickness t of vibration body: 0.0017 (m)
Gas layer thickness L: 0.03 (m)
Case length a: 0.1 (m)
Case length b: 0.1 (m)
Young's modulus E of vibrator: 1.0 (GPa)
Poisson's ratio σ: 0.4
Mode order: p = q = 1

一方、式（２）においては、バネマス系の項（右辺第１項、すなわち式（１）の右辺）と屈曲系の項（右辺第２項）とが加算される。このため、式（２）により得られる共振周波数は、バネマス系の共振周波数より高いものとなり、吸音のピーク周波数を低く設定することが難しい場合がある。このような吸音構造においては、バネマス系による共振周波数と、板又は膜の弾性による弾性振動による屈曲系の共振周波数との関連性は十分に解明されておらず、低音域で高い吸音効果を奏する吸音構造が確立されていないのが実情である。   On the other hand, in the expression (2), the term of the spring mass system (the first term on the right side, that is, the right side of the expression (1)) and the term of the bending system (the second term on the right side) are added. For this reason, the resonance frequency obtained by Equation (2) is higher than the resonance frequency of the spring mass system, and it may be difficult to set the peak frequency of sound absorption low. In such a sound absorbing structure, the relationship between the resonance frequency due to the spring mass system and the resonance frequency of the bending system due to the elastic vibration due to the elasticity of the plate or film has not been sufficiently elucidated, and has a high sound absorption effect in the low frequency range. The fact is that no sound absorption structure has been established.

本発明の発明者らは、屈曲系の基本振動周波数の値をｆａ（式（２）の右辺第２項）、バネマス系の共振周波数の値をｆｂ（式（２）の右辺第１項）とした場合に、以下の式（３）の関係を満足するように上記パラメータを設定すれば、高い吸音効果が得られるという知見を得た。これにより、屈曲系の基本振動が背後の気体層のバネ成分と連成して、バネマス系の共振周波数と屈曲系の基本周波数との間の帯域に振幅の大きな振動が励振され（屈曲系共振周波数ｆａ＜ピーク周波数ｆ＜バネマス系基本周波数ｆｂ）、吸音率が高くなる。

Figure 2010097147
The inventors of the present invention set the value of the fundamental vibration frequency of the bending system to fa (the second term on the right side of Equation (2)), and the value of the resonance frequency of the spring mass system to fb (the first term on the right side of Equation (2)). In this case, it was found that if the above parameters are set so as to satisfy the relationship of the following expression (3), a high sound absorption effect can be obtained. As a result, the fundamental vibration of the bending system is coupled with the spring component of the gas 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 (flexural system resonance). The frequency fa <peak frequency f <spring mass system fundamental frequency fb), and the sound absorption rate increases.
Figure 2010097147

さらに、上記パラメータを以下の式（４）に設定する場合、ピーク周波数がバネマス系の共振周波数より十分に小さくなる。この場合、低次の弾性振動のモードにより屈曲系の基本周波数がバネマス系の共振周波数より十分に小さく、３００（Ｈｚ）以下の周波数の音を吸音する吸音構造として適しているという知見が得られた。

Figure 2010097147
このように、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、ピーク周波数を低くした吸音構造を構成することができる。 Furthermore, when the parameter is set in the following equation (4), the peak frequency is sufficiently smaller than the resonance frequency of the spring mass system. In this case, it is found 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. It was.
Figure 2010097147
 Thus, by setting various parameters so as to satisfy the conditions of the expressions (3) and (4), it is possible to configure a sound absorbing structure with a reduced peak frequency.

また、吸音構造１０は、中空領域ｈ2及びｈ3に対応する部分がヘルムホルツ共鳴器として機能する。これらの部分がヘルムホルツ共鳴器として機能するのは、孔部１２ａが設けられているためである。すなわち、これらの部分は、孔部１２ａの内部にある気体を質量成分とし、中空領域ｈ2又はｈ3の気体層をバネ成分としたバネマス系を形成する。なお、複数の孔部１２ａの大きさ（孔径又は面積）は、それぞれ同一でなくてもよい。 In the sound absorbing structure 10, the portions corresponding to the hollow regions h 2 and h 3 function as Helmholtz resonators. These portions function as Helmholtz resonators because the holes 12a are provided. That is, these portions form a spring mass system in which the gas inside the hole 12a is a mass component and the gas layer in the hollow region h 2 or h 3 is a spring component. In addition, the magnitude | size (hole diameter or area) of the some hole part 12a does not need to be the same, respectively.

このように、本実施形態の吸音構造１０は、板・膜振動吸音構造として機能するための中空領域とヘルムホルツ共鳴器として機能するための中空領域とを独立に設けているため、かかる中空領域の一部又は全部が共有される構成に比べ、一方が他方に与える影響を抑制することが可能となる。すなわち、この吸音構造１０によれば、板・膜振動吸音構造に係る吸音特性（吸音率の周波数特性）とヘルムホルツ共鳴器に係る吸音特性とをより自由に設計することが可能となる。   As described above, the sound absorbing structure 10 of the present embodiment is provided with a hollow region for functioning as a plate / membrane vibration sound absorbing structure and a hollow region for functioning as a Helmholtz resonator independently. Compared to a configuration in which a part or all of them are shared, the influence of one on the other can be suppressed. That is, according to the sound absorbing structure 10, it is possible to more freely design the sound absorption characteristics (frequency characteristics of the sound absorption coefficient) related to the plate / membrane vibration absorption structure and the sound absorption characteristics related to the Helmholtz resonator.

また、本実施形態の吸音構造１０は、中空領域のうちの上面の面積が大きいものを板・膜振動吸音構造として機能させ、中空領域のうちの上面の面積が小さいものをヘルムホルツ共鳴器として機能させる構成を採用することにより、中空領域のすべてを板・膜振動吸音構造として機能させる構成に比べ、吸音効率の改善を期待することができる。なぜならば、板・膜振動吸音構造においては、振動部分（すなわち閉塞部材１２）の面積が小さいと、そのぶん振動が生じにくくなり、吸音効率が低下する傾向がある一方で、ヘルムホルツ共鳴器においては、質量成分を構成するのが孔部１２ａの内部にある気体であるため、上面の面積自体は吸音にほとんど影響を与えないからである。   Further, the sound absorbing structure 10 of the present embodiment functions a plate / membrane vibration absorbing structure having a large upper surface area in the hollow region, and functions as a Helmholtz resonator having a small upper surface area in the hollow region. By adopting the configuration, it is possible to expect an improvement in sound absorption efficiency as compared with a configuration in which all of the hollow region functions as a plate / membrane vibration absorption structure. This is because, in the plate / membrane vibration absorption structure, if the area of the vibration part (that is, the closing member 12) is small, the vibration hardly occurs and the sound absorption efficiency tends to decrease. This is because the mass component constitutes the gas inside the hole 12a, so that the area of the upper surface itself hardly affects the sound absorption.

さらに、本実施形態において、中空領域ｈ2は、中空領域ｈ1を円柱状に設けるに際して生じた、いわば間隙の部分である。つまり、本実施形態の吸音構造１０は、板・膜振動吸音構造を複数設けるに際して生じた間隙部分をヘルムホルツ共鳴器として有効に利用するものであるともいえる。板・膜振動吸音構造を複数設ける場合において、間隙部分に閉塞部材１２を設けなければ、その間隙部分は吸音体として機能せず、また、間隙部分の上面に孔部１２ａを設けなければ、その上面の面積が小さくなるほど吸音効率が低下する。すなわち、本実施形態の吸音構造１０は、間隙部分の上面に孔を空けるという簡単な加工を施すだけで、板・膜振動吸音構造を複数設けるに際して生じた微小な間隙部分をより有効に活用させることができるものである。 Further, in the present embodiment, the hollow region h 2 is a so-called gap portion generated when the hollow region h 1 is provided in a cylindrical shape. That is, it can be said that the sound absorbing structure 10 of the present embodiment effectively uses a gap portion generated when a plurality of plate / membrane vibration absorbing structures are provided as a Helmholtz resonator. In the case of providing a plurality of plate / membrane vibration absorbing structures, if the closing member 12 is not provided in the gap portion, the gap portion does not function as a sound absorber, and if the hole 12a is not provided on the upper surface of the gap portion, As the area of the upper surface decreases, the sound absorption efficiency decreases. In other words, the sound absorbing structure 10 of the present embodiment makes more effective use of the minute gap portions generated when a plurality of plate / membrane vibration absorbing structures are provided by simply performing a process of forming a hole in the upper surface of the gap portion. It is something that can be done.

［変形例］
本発明は、上述した実施形態と異なる形態での実施が可能である。以下に示す変形例は、本発明に適用可能な変形の一例である。なお、これらの変形例は、必要に応じて、各々を適宜に組み合わせて実施されてもよい。また、以下の説明においては、既に説明した構成と共通する構成に対して同一の符号を付し、その説明を適宜省略する。 [Modification]
The present invention can be implemented in a form different from the above-described embodiment. The following modifications are examples of modifications applicable to the present invention. In addition, these modifications may be implemented by appropriately combining each as required. Moreover, in the following description, the same code | symbol is attached | subjected with respect to the structure which is already demonstrated, and the description is abbreviate | omitted suitably.

（１）変形例１
上述した実施形態において、中空領域ｈ1は、本発明の「第１領域」の一例であり、中空領域ｈ2及びｈ3は、本発明の「第２領域」の一例である。しかしながら、本発明に係る吸音構造は、中空領域ｈ3に相当する領域を設けないでもよい。また、上述した吸音構造１０の構成において、閉塞部材１２の中空領域ｈ2に面する位置に孔部を設けずに、中空領域ｈ3に面する位置のみに孔部を設けるようにしてもよい。この構成の場合には、中空領域ｈ1及びｈ2が本発明の「第１領域」の一例となり、中空領域ｈ3が本発明の「第２領域」の一例となる。 (1) Modification 1
In the embodiment described above, the hollow region h 1 is an example of the “first region” in the present invention, and the hollow regions h 2 and h 3 are examples of the “second region” in the present invention. However, the sound absorbing structure according to the present invention may not provide a region corresponding to the hollow region h 3 . In the structure of the sound absorbing structure 10 described above, the hole may be provided only at the position facing the hollow region h 3 without providing the hole at the position facing the hollow region h 2 of the closing member 12. . In the case of this configuration, the hollow regions h 1 and h 2 are examples of the “first region” of the present invention, and the hollow region h 3 is an example of the “second region” of the present invention.

（２）変形例２
本発明に係る吸音構造は、上述した吸音構造１０に代えて、その側面部１１２を省略し、隔壁部１１１を外部に露出させた構成としてもよい。また、中空領域ｈ1及びｈ2は、図１に示した数に限らず、より多く（又は少なく）してもよい。
また、吸音構造１０を所定の面（壁面など）に取り付ける場合であれば、その取り付ける面を底面部１１３の代用としてもよい。すなわち、本発明に係る吸音構造は、隔壁部１１１や側面部１１２の底面側が取り付けるべき面に沿った形状にされていれば、筐体１１から底面部１１３を除いた構成にしてもよい。この場合、隔壁部１１１及び側面部１１２は、上面側の開口部を閉塞部材１２によって塞がれ、底面側の開口部を所定の面によって塞がれる。 (2) Modification 2
The sound absorbing structure according to the present invention may be configured such that the side surface portion 112 is omitted and the partition wall portion 111 is exposed to the outside instead of the sound absorbing structure 10 described above. Further, the number of the hollow regions h 1 and h 2 is not limited to the number shown in FIG. 1, and may be larger (or smaller).
Further, if the sound absorbing structure 10 is attached to a predetermined surface (wall surface or the like), the attachment surface may be used as a substitute for the bottom surface portion 113. That is, the sound absorbing structure according to the present invention may be configured by removing the bottom surface portion 113 from the housing 11 as long as the bottom surface side of the partition wall portion 111 and the side surface portion 112 is shaped along the surface to be attached. In this case, as for the partition part 111 and the side part 112, the opening part on the upper surface side is closed by the closing member 12, and the opening part on the bottom surface side is closed by a predetermined surface.

（３）変形例３
本発明において、吸音構造及び中空領域の形状は、任意であり、取り付ける面の形状や所望する吸音特性に応じて決めてよい。また、第１領域及び第２領域の形状や配置についても、上述した実施形態のものに限らない。 (3) Modification 3
In the present invention, the shape of the sound absorbing structure and the hollow region is arbitrary, and may be determined according to the shape of the surface to be attached and the desired sound absorbing characteristics. Further, the shape and arrangement of the first region and the second region are not limited to those of the above-described embodiment.

図４は、取り付ける面が平面でない場合の吸音構造を孔部がある位置において切断した場合を例示する断面図である。同図に示すように、吸音構造２０は、筐体２１と、閉塞部材２２とを備える。なお、吸音構造２０は、孔部２２ａを除き、図４の紙面に垂直な方向について同一の形状を有しているものとする。かかる構成において、筐体２１は、第１領域ａ1と第２領域ａ2とを形成し、閉塞部材２２は、第２領域ａ2に面する部分に孔部２２ａを有する。これにより、吸音構造２０は、第１領域ａ1に相当する部分を板・膜振動吸音構造として機能させ、第２領域ａ2に相当する部分をヘルムホルツ共鳴器として機能させることができる。 FIG. 4 is a cross-sectional view illustrating a case where the sound absorbing structure when the mounting surface is not a plane is cut at a position where a hole is present. As shown in the figure, the sound absorbing structure 20 includes a housing 21 and a closing member 22. The sound absorbing structure 20 has the same shape in the direction perpendicular to the paper surface of FIG. 4 except for the hole 22a. In such a configuration, the casing 21 forms a first area a 1 and a second area a 2, and the closing member 22 has a hole 22 a in a portion facing the second area a 2 . Thus, the sound absorbing structure 20 can cause the portion corresponding to the first region a 1 to function as a plate / membrane vibration absorbing structure, and allow the portion corresponding to the second region a 2 to function as a Helmholtz resonator.

図５は、吸音特性が異なる複数のヘルムホルツ共鳴器を構成する場合の吸音構造を孔部がある位置において切断した場合を例示する断面図である。同図に示すように、吸音構造３０は、筐体３１と、閉塞部材３２とを備える。なお、吸音構造３０は、孔部３２ａを除き、図５の紙面に垂直な方向について同一の形状を有しているものとする。かかる構成において、筐体３１は、容積が等しい複数の第１領域ａ1を形成するとともに、容積（高さ）が相異なる複数の第２領域ａ2を形成する。また、閉塞部材３２は、第２領域ａ2に面する部分に孔部３２ａを有する。 FIG. 5 is a cross-sectional view illustrating a case where the sound absorption structure in the case where a plurality of Helmholtz resonators having different sound absorption characteristics is formed is cut at a position where there is a hole. As shown in the figure, the sound absorbing structure 30 includes a housing 31 and a closing member 32. The sound absorbing structure 30 has the same shape in the direction perpendicular to the paper surface of FIG. 5 except for the hole 32a. In such a configuration, the casing 31 forms a plurality of first regions a 1 having the same volume, and forms a plurality of second regions a 2 having different volumes (heights). Also, the closing member 32 has a hole 32a in a portion facing the second region a 2.

なお、ヘルムホルツ共鳴器の吸音特性を異ならせることは、孔部３２ａの形状（すなわち面積）を異ならせることによって行われてもよい。また、第１領域ａ1の高さやこれに面する閉塞部材３２の面積を異ならせることにより、板・膜振動吸音構造の吸音特性を互いに異ならせてもよい。このように、ヘルムホルツ共鳴器及び板・膜振動吸音構造の形状などを多様に異ならせることで、吸音率のピークが異なる多数の吸音体を組み合わせ、より広い周波数帯域について良好な吸音特性を得ることが可能になる。 The sound absorption characteristics of the Helmholtz resonator may be changed by changing the shape (that is, the area) of the hole 32a. Further, the sound absorption characteristics of the plate / membrane vibration absorption structure may be made different from each other by changing the height of the first region a 1 and the area of the blocking member 32 facing the first region a 1 . In this way, by combining various shapes of the Helmholtz resonator and the sound absorption structure of the plate / membrane vibration absorption structure, it is possible to combine a number of sound absorbers with different peaks in the sound absorption coefficient and obtain good sound absorption characteristics over a wider frequency band. Is possible.

（４）変形例４
図５に示す構成において、吸音構造３０のヘルムホルツ共鳴器の底面を構成する部分を筐体３１とは別の部材により構成し、これを移動可能に構成してもよい。
図６は、吸音構造３０の変形例を例示する図である。同図において、吸音構造３０ａは、筐体３１１と、複数の可動機構３１２と、閉塞部材３２とを備える。可動機構３１２は、図中の矢印に示す方向に移動可能であり、第２領域ａ2の高さ及び容積を変化させることが可能である。このようにすれば、ヘルムホルツ共鳴器の吸音特性を必要に応じて変化させることが可能となる。
なお、同様の機構は、板・膜振動吸音構造の底面に設けられてもよい。 (4) Modification 4
In the configuration shown in FIG. 5, the portion constituting the bottom surface of the Helmholtz resonator of the sound absorbing structure 30 may be configured by a member different from the casing 31 and may be configured to be movable.
FIG. 6 is a diagram illustrating a modified example of the sound absorbing structure 30. In the figure, the sound absorbing structure 30 a includes a housing 311, a plurality of movable mechanisms 312, and a closing member 32. The movable mechanism 312 can move in the direction indicated by the arrow in the figure, and can change the height and volume of the second region a 2 . If it does in this way, it will become possible to change the sound absorption characteristic of a Helmholtz resonator as needed.
A similar mechanism may be provided on the bottom surface of the plate / membrane vibration absorbing structure.

（５）変形例５
ヘルムホルツ共鳴器の吸音特性を異ならせることは、その孔部に頚部（ネック部）を設けることで行われてもよい。
図７は、吸音構造１０の孔部１２ａに頚部を設けた構成を示す図である。同図において、筒状部材１３は、中空領域ｈ2から外部に向かって開口した円筒形の中空の部材であり、孔部１２ａに取り付けられてヘルムホルツ共鳴器の頚部として機能する。筒状部材１３の長さを必要に応じて定めれば、ヘルムホルツ共鳴器における吸音特性を適宜に変更することが可能となる。 (5) Modification 5
Differentiating the sound absorption characteristics of the Helmholtz resonator may be performed by providing a neck (neck) in the hole.
FIG. 7 is a view showing a configuration in which a neck portion is provided in the hole portion 12 a of the sound absorbing structure 10. In the figure, a cylindrical member 13 is a cylindrical hollow member opened from the hollow region h 2 to the outside, and is attached to the hole 12a and functions as a neck of the Helmholtz resonator. If the length of the cylindrical member 13 is determined as necessary, the sound absorption characteristics of the Helmholtz resonator can be appropriately changed.

（６）変形例６
本発明において、閉塞部材のうちの振動体として機能する部分（以下、単に「振動体」ともいう。）は、その全体が一様な構成であってもよいし、その一部が他の部分と異なる質量を有する構成であってもよい。この構成において、当該一部は、他の部分と異なる密度を有するものであってもよいし、他の部分と同じ密度だが厚さが異なるものであってもよい。さらには、当該一部は、質量を付与するために他の部材を接着等により取り付けた構成であってもよい。なお、当該一部は、振動体の中央にあると望ましい。 (6) Modification 6
In the present invention, the part of the closing member that functions as a vibrating body (hereinafter also simply referred to as “vibrating body”) may have a uniform configuration as a whole, or a part thereof may be another part. The structure which has a different mass from may be sufficient. In this configuration, the part may have a density different from the other parts, or may have the same density as the other parts but a different thickness. Further, the part may have a configuration in which another member is attached by adhesion or the like in order to impart mass. Note that the part is preferably in the center of the vibrating body.

図８は、底面が１００ｍｍ×１００ｍｍの正方形で厚さが１０ｍｍの空気層を形成する筐体１１に、１００ｍｍ×１００ｍｍの正方形で厚さが０．８５ｍｍの閉塞部材１２を固着し、閉塞部材１２の中央部（大きさ２０ｍｍ×２０ｍｍ、厚さ０．８５ｍｍ）の面密度を変化させた際の吸音構造１０の吸音率のシミュレーション結果を示す図である。なお、シミュレーションは、ＪＩＳ Ａ１４０５−２（音響管による吸音率及びインピーダンスの測定−第２部：伝達関数法）に従って吸音構造１０を配置した音響室の音場を有限要素法により求め、その伝達関数より吸音特性を算出するものである。なお、本シミュレーションにおいては、振動体の質量成分による作用に注目し、隔壁部１１１及び孔部１２ａの作用を除外することを目的に、第２開口部１１２を設けない構成を用いた。つまり、本構成においては、閉塞部材１２の全体が振動体として機能する。   In FIG. 8, a closing member 12 having a square of 100 mm × 100 mm and a thickness of 0.85 mm is fixed to a housing 11 forming a 10 mm thick air layer having a square bottom of 100 mm × 100 mm. It is a figure which shows the simulation result of the sound absorption rate of the sound absorption structure 10 at the time of changing the surface density of the center part (size 20mm * 20mm, thickness 0.85mm) of this. In the simulation, the sound field of the acoustic chamber in which the sound absorbing structure 10 is arranged is obtained by a finite element method according to JIS A1405-2 (measurement of sound absorption coefficient and impedance by an acoustic tube—part 2: transfer function method), and the transfer function is obtained. The sound absorption characteristic is calculated. In this simulation, attention is paid to the action due to the mass component of the vibrating body, and a configuration in which the second opening 112 is not provided is used to exclude the action of the partition wall 111 and the hole 12a. That is, in this configuration, the entire closing member 12 functions as a vibrating body.

図８に示すシミュレーションに用いた閉塞部材１２の構成は、以下のとおりである。なお、面密度及び平均密度の単位は、いずれも「ｇ／ｍ2」である。また、閉塞部材１２のうち中央部を除いた部分の面密度は、いずれも７９９（ｇ／ｍ2）である。
（１）中央部の面密度：３９９．５、振動体の平均密度：７８３
（２）中央部の面密度：７９９、振動体の平均密度：７９９
（３）中央部の面密度：１１９９、振動体の平均密度：８１５
（４）中央部の面密度：１５９８、振動体の平均密度：８３１
（５）中央部の面密度：２２９７、振動体の平均密度：８６３ The configuration of the closing member 12 used in the simulation shown in FIG. 8 is as follows. The unit of the surface density and the average density is “g / m 2 ”. The surface density of the portion excluding the central portion of the closure member 12 are both 799 (g / m 2).
(1) Center area density: 399.5, average density of vibrator: 783
(2) Area density at center: 799, average density of vibrator: 799
(3) Center area density: 1199, average density of vibrator: 815
(4) Area density at center: 1598, average density of vibrators: 831
(5) Area density at center: 2297, average density of vibrator: 863

図８に示すように、吸音率は、３００〜５００Ｈｚの間と、７００Ｈｚ付近において高くなっている。７００Ｈｚ付近の吸音率のピークは、閉塞部材１２の質量成分と空気層のバネ成分によって形成されるバネマス系の共振によるものである。本シミュレーションの吸音構造においては、バネマス系の共振周波数での吸音率をピークとして音が吸音されており、中央部の面密度を大きくしても、閉塞部材１２全体としての質量は大きく変わらないので、バネマス系の共振周波数も大きくは変わらない。   As shown in FIG. 8, the sound absorption coefficient is high between 300 to 500 Hz and in the vicinity of 700 Hz. The peak of the sound absorption coefficient near 700 Hz is due to resonance of the spring mass system formed by the mass component of the closing member 12 and the spring component of the air layer. In the sound absorbing structure of this simulation, 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 closing member 12 does not change greatly. The resonance frequency of the spring mass system does not change greatly.

一方、３００〜５００Ｈｚの間での吸音率のピークは、閉塞部材１２の屈曲振動によって形成される屈曲系の共振によるものである。本シミュレーションの吸音構造においては、屈曲系の共振周波数での吸音率が低音域側のピークとして表れており、中央部の面密度を異ならせると、屈曲系の共振周波数がバネマス系の共振周波数よりも大きく変化する。また、屈曲系の共振周波数は、図示のとおり、中央部の面密度が大きくなるほど低くなる。   On the other hand, the peak of the sound absorption coefficient between 300 and 500 Hz is due to the resonance of the bending system formed by the bending vibration of the closing member 12. In the sound absorption structure of this simulation, the sound absorption coefficient at the resonance frequency of the bending system appears as a peak on the low frequency side, and if the surface density of the central part is different, the resonance frequency of the bending system is higher than the resonance frequency of the spring mass system. Also changes significantly. Further, as shown in the figure, the resonance frequency of the bending system decreases as the surface density at the center increases.

一般に、屈曲系の共振周波数は、閉塞部材１２の弾性振動を支配する運動方程式で決定され、閉塞部材１２の密度（及び面密度）に反比例する。また、屈曲系の共振周波数は、固有振動の腹（振幅が極大値となる場合）の密度の影響を強く受ける。本シミュレーションにおいては、１×１の固有モードの腹となる領域（すなわち中央部）を異なる面密度で形成したことにより、屈曲系の共振周波数が変化したのである。   In general, the resonance frequency of the bending system is determined by an equation of motion that governs the elastic vibration of the closing member 12 and is inversely proportional to the density (and surface density) of the closing member 12. In addition, the resonance frequency of the bending system is strongly influenced by the density of the antinodes of natural vibration (when the amplitude is a maximum value). In this simulation, the resonance frequency of the bending system is changed by forming the antinodes of the 1 × 1 natural mode (that is, the central portion) with different surface densities.

図８に示すシミュレーション結果は、閉塞部材１２の中央部の面密度をその他の部分の面密度より大きくすると、吸音のピークとなる周波数のうち、低音域側の吸音率のピークがさらに低音域側へ移動することを表している。したがって、中央部の面密度を変更すれば、吸音のピークとなる周波数の一部をさらに低音域側又は高音域側に移動（シフト）させることが可能である。   The simulation result shown in FIG. 8 shows that when the surface density of the central portion of the blocking member 12 is made larger than the surface density of the other portions, the sound absorption coefficient peak on the low sound side is further lower than the sound absorption peak frequency. It represents moving to. Therefore, if the surface density of the central part is changed, it is possible to move (shift) a part of the frequency at which the sound absorption peak occurs further to the low sound range side or the high sound range side.

以上のことから、本発明に係る吸音構造においては、中央部の面密度を変えることによって、吸音のピーク周波数を変える（シフトさせる）ことができるといえる。すなわち、本発明に係る吸音構造によれば、振動体の中央部の質量を異ならせるだけで、吸音構造全体としての質量を大きく変えることなく、より低い周波数の音を吸音することができるようになる。これにより、本発明に係る吸音構造は、吸音対象の音の周波数が変化する場合においても、振動体の中央部の質量を変化させるだけで、音の変化に対応することが可能となる。   From the above, in the sound absorbing structure according to the present invention, it can be said that the peak frequency of sound absorption can be changed (shifted) by changing the surface density of the central portion. That is, according to the sound absorbing structure according to the present invention, it is possible to absorb a sound having a lower frequency without greatly changing the mass of the entire sound absorbing structure only by changing the mass of the central portion of the vibrating body. Become. As a result, the sound absorbing structure according to the present invention can cope with a change in sound only by changing the mass of the central part of the vibrating body even when the frequency of the sound to be absorbed changes.

（７）変形例７
本発明において、閉塞部材は、一部又は全部の第２領域に面する位置に孔部を設けない構成としてもよい。あるいは、閉塞部材は、一部又は全部の第１領域に面する位置にも孔部を設けるようにしてもよい。 (7) Modification 7
In the present invention, the closing member may have a configuration in which no hole is provided at a position facing a part or all of the second region. Or you may make it provide a hole also in the position where a closure member faces the 1st field of a part or all.

（８）変形例８
本発明は、吸音構造を群として複数設けたものであってもよい。
図９は、本発明に係る吸音構造群を例示する図である。この吸音構造群４０は、上述した実施形態の吸音構造１０を連結し、一体にした構成である。筐体４１は、２つの筐体１１を連結し、側面の一つを互いに共通にしたような構成である。すなわち、筐体４１は、共通の側面に相当する隔壁をその内部（破線の位置）に有する。閉塞部材４２は、筐体４１の上面の開口部を塞ぐものであるが、一方の吸音構造と他方の吸音構造とについて一の共通の部材であってもよいし、図中の破線の位置で分割され、材質や厚さが互いに異なるように構成されてもよい。 (8) Modification 8
In the present invention, a plurality of sound absorbing structures may be provided as a group.
FIG. 9 is a diagram illustrating a sound absorbing structure group according to the present invention. The sound absorbing structure group 40 is configured by connecting and integrating the sound absorbing structures 10 of the above-described embodiments. The housing 41 is configured such that the two housings 11 are connected and one of the side surfaces is made common. That is, the housing | casing 41 has the partition equivalent to a common side surface in the inside (position of a broken line). The closing member 42 closes the opening on the upper surface of the housing 41, but may be a common member for one sound absorbing structure and the other sound absorbing structure, or at the position of the broken line in the figure. It may be divided so that the material and thickness are different from each other.

なお、本発明に係る吸音構造群において、複数の吸音構造は、いずれも同種（同じ構成）であってもよいが、異種の吸音構造の組み合わせであってもよい。すなわち、本発明に係る吸音構造群が第１の吸音構造と第２の吸音構造とを備える場合において、第１の吸音構造と第２の吸音構造とは、中空領域、第１領域及び第２領域の少なくともいずれかが互いに同一でない構成（形状や容積）であってもよいし、孔部が互いに同一でない構成（形状や面積）であってもよい。本発明に係る吸音構造群において、異種の吸音構造を組み合わせた場合には、より多くの音域を吸音対象とすることが可能となる。   In the sound absorbing structure group according to the present invention, the plurality of sound absorbing structures may all be the same type (same configuration), or may be a combination of different types of sound absorbing structures. That is, when the sound absorbing structure group according to the present invention includes the first sound absorbing structure and the second sound absorbing structure, the first sound absorbing structure and the second sound absorbing structure include the hollow region, the first region, and the second region. A configuration (shape or volume) in which at least one of the regions is not the same may be used, or a configuration (shape or area) in which the holes are not the same. In the sound absorbing structure group according to the present invention, when different kinds of sound absorbing structures are combined, a larger number of sound ranges can be targeted for sound absorption.

（９）変形例９
本発明は、上述した吸音構造又は吸音構造群を備える音響室としても実施可能である。かかる音響室は、例えば、スピーカや防音室などの、楽音の聴取の用に供される物品や構造物である。また、船舶、飛行機、車両等の乗り物の壁面や、浴室や浴槽などの壁面に本発明を適用し、音響室を構成するようにしてもよい。本発明は、特定の周波数の音が騒音として生じるような場所に適用するに好適なものであるため、かかる物品や構造物に用いると、騒音の抑制に一定の効果を奏する。 (9) Modification 9
The present invention can also be implemented as an acoustic chamber provided with the above-described sound absorbing structure or sound absorbing structure group. Such an acoustic room is an article or a structure provided for listening to musical sounds, such as a speaker or a soundproof room. Further, the present invention may be applied to a wall surface of a vehicle such as a ship, an airplane, or a vehicle, or a wall surface such as a bathroom or a bathtub to constitute an acoustic room. Since the present invention is suitable for application to a place where sound of a specific frequency is generated as noise, when used in such an article or structure, there is a certain effect in suppressing noise.

吸音構造の構造を示す図Diagram showing the structure of sound absorption structure 筐体の構造を示す断面図Sectional view showing the structure of the housing 筐体及び閉塞部材の構造を示す断面図Sectional drawing which shows structure of housing | casing and closure member 吸音構造の構造を示す断面図Sectional view showing structure of sound absorbing structure 吸音構造の構造を示す断面図Sectional view showing structure of sound absorbing structure 吸音構造の構造を示す断面図Sectional view showing structure of sound absorbing structure 筒状部材の構造を示す図The figure which shows the structure of a cylindrical member 吸音率のシミュレーション結果を示す図The figure which shows the simulation result of the sound absorption rate 吸音構造群の外観を示す図The figure which shows the appearance of the sound absorption structure group

符号の説明Explanation of symbols

１０、２０、３０…吸音構造、４０…吸音構造群、１１、２１、３１、４１…筐体、１１１…隔壁部、１１２…側面部、１１３…底面部、１２、２２、３２、４２…閉塞部材、１３…筒状部材 DESCRIPTION OF SYMBOLS 10, 20, 30 ... Sound absorption structure, 40 ... Sound absorption structure group, 11, 21, 31, 41 ... Case, 111 ... Partition part, 112 ... Side part, 113 ... Bottom part, 12, 22, 32, 42 ... Blocking Member, 13 ... tubular member

Claims (10)

開口した中空領域を第１領域と第２領域とに隔てる隔壁を有する筐体と、
板状又は膜状であり、前記筐体に支持されて前記中空領域の開口部を塞ぐ閉塞部材とを備え、
前記閉塞部材が、前記第２領域に面する位置に孔部を有する
ことを特徴とする吸音構造。 A housing having a partition that separates the open hollow region into a first region and a second region;
It is plate-shaped or film-shaped, and includes a closing member that is supported by the housing and closes the opening of the hollow region,
The sound absorbing structure, wherein the blocking member has a hole at a position facing the second region. 前記閉塞部材の前記第１領域に面する面積が前記第２領域に面する面積より大であることを特徴とする請求項１に記載の吸音構造。   The sound absorbing structure according to claim 1, wherein an area facing the first region of the closing member is larger than an area facing the second region. 前記第２領域の容積が前記第１領域の容積より小であることを特徴とする請求項１に記載の吸音構造。   The sound absorbing structure according to claim 1, wherein the volume of the second region is smaller than the volume of the first region. 前記第２領域から外部に向かって開口する筒状部材を前記孔部に備えることを特徴とする請求項１に記載の吸音構造。   The sound absorbing structure according to claim 1, wherein the hole includes a cylindrical member that opens from the second region toward the outside. 前記第２領域及び前記筒状部材を複数備え、
複数の前記筒状部材は、その長さ及び断面積の少なくともいずれかが互いに同一でない
ことを特徴とする請求項４に記載の吸音構造。 A plurality of the second region and the cylindrical member;
The sound absorbing structure according to claim 4, wherein at least one of the length and the cross-sectional area of the plurality of cylindrical members is not the same. 前記隔壁が、前記第１領域を複数形成するとともに、前記第２領域を複数の前記第１領域の間隙に形成することを特徴とする請求項１に記載の吸音構造。   2. The sound absorbing structure according to claim 1, wherein the partition wall forms a plurality of the first regions, and forms the second region in gaps between the plurality of first regions. 請求項１ないし４のいずれかに記載の吸音構造を複数組み合わせて備えることを特徴とする吸音構造群。   A sound absorbing structure group comprising a plurality of sound absorbing structures according to claim 1 in combination. 複数の前記吸音構造の前記第１領域又は第２領域の容積及び前記孔部の面積の少なくともいずれかが互いに同一でないことを特徴とする請求項７に記載の吸音構造群。   The sound absorbing structure group according to claim 7, wherein at least one of a volume of the first region or the second region and an area of the hole portion of the plurality of sound absorbing structures is not the same. 複数の前記吸音構造が一の板状又は膜状の部材により前記閉塞部材を構成することを特徴とする請求項７に記載の吸音構造群。   The sound absorbing structure group according to claim 7, wherein the plurality of sound absorbing structures constitute the closing member by a single plate-like or film-like member. 請求項１ないし６のいずれかに記載の吸音構造又は請求項７ないし９のいずれかに記載の吸音構造群を備えることを特徴とする音響室。   An acoustic room comprising the sound absorbing structure according to any one of claims 1 to 6 or the sound absorbing structure group according to any one of claims 7 to 9.
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