JP2009167701A - Sound absorbing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing structure which can stabilize sound absorbing performance, and which can enhance the sound absorbing performance, especially, in low-to-mid frequency ranges. <P>SOLUTION: A sound absorbing body 10, which is provided in an installation surface F, comprises a casing 11 which is composed of a rigid body, and a membrane-like body 12 which is provided on the casing 11. The casing 11 is equipped with a peripheral wall 14 which is erected from the installation surface F, and a top wall 15 which is continuously provided on the one-end side of the peripheral wall 14 and positioned at a predetermined spacing from the installation surface F. The membrane-like body 12 is provided in a tensed state on the other-end side of the peripheral wall 14, and placed on the installation surface F in such a manner as to be capable of being vibrated by a sound incident the sound absorbing body 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sound absorbing structure, and more particularly to a sound absorbing structure that can stably exhibit sound absorbing performance.

  Conventionally, sound absorbers have been used in various indoor spaces and the like, and such sound absorbers are required to absorb sound in the middle and low frequency range of about 250 Hz in order to create a comfortable sound field. As such a sound absorber, one disclosed in Patent Document 1 is known. The sound absorbing body of the same document includes a vibration damping material made of an elastic body provided between the plate-like body and the frame, and a sound absorbing action is obtained by vibrating the plate-like body through the vibration damping material. It has become.

JP 2005-134653 A

  However, in the sound absorbing body, when placed on the floor surface and used, a load to step on or walk on the plate-like body is applied, so that the damping material is easily deformed or damaged. Become. As a result, the vibration of the plate-like body becomes unstable and the sound absorption performance is deteriorated with time. By the way, although sound absorption can be performed by the carpet by laying the carpet or the like on the floor surface, there is a disadvantage that the above-described sound absorbing action in the middle and low range cannot be sufficiently obtained.

[Object of invention]
The present invention has been devised by paying attention to such inconveniences, and the purpose thereof is to stabilize the sound absorption performance, and in particular, to improve the sound absorption performance in the mid-low range. Is to provide.

In order to achieve the above object, the sound absorbing structure of the present invention is a sound absorbing structure in which a sound absorbing body having a housing made of a rigid body and a film-like body provided in the housing is provided on an installation surface.
The housing includes a peripheral wall standing from the installation surface, and a top wall that is connected to one end side of the peripheral wall and is spaced a predetermined distance from the installation surface, and opens the installation surface side.
The film-like body is stretched on the other end side of the peripheral wall, and is configured to be placed on the installation surface so as to be vibrated by sound incident on the sound absorbing body.

  In the present invention, a configuration in which a porous material is provided in the housing and / or on the top wall may be adopted.

  According to the present invention, even when a sound absorbing body is mounted on an installation surface such as a floor, the film-like body can be protected by the housing. As a result, the sound absorbing action in the middle and low range by the film-like body can be stably obtained over a long period of time, and a comfortable sound field can be maintained well.

  In addition, when a porous material is provided in the housing and / or on the top wall, the sound absorption effect by the porous material and the sound absorption effect by the film-like body can be obtained, so the sound range that exhibits good sound absorption performance is expanded. can do.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view schematically showing the sound absorbing structure according to the first embodiment. In this figure, a plurality of sound absorbers 10 are placed on an installation surface F such as a floor surface. The sound absorber 10 includes a housing 11 made of a rigid body and a film-like body 12 provided on the housing 11. Each sound absorber 10 is disposed so as to be in close contact with the sound absorber 10 adjacent in the lateral direction.

  The housing 11 is provided in a box shape that opens on the installation surface F side, that is, the lower side in FIG. Specifically, it includes a peripheral wall 14 erected from the installation surface F and a top wall 15 connected to one end side, that is, the upper end side of the peripheral wall 14. The top wall 15 is positioned so as to be substantially parallel to the installation surface F, and is provided so as to be positioned at an interval of 5 mm to 50 mm, preferably 10 to 30 mm from the film-like body 12. The housing 11 is fixed to the installation surface F via a connecting means such as a screw (not shown). Examples of the planar shape of the housing 11 include a square, a rectangle, a circle, an ellipse, a polygon, and the like, and the size of the case 11 is within a square (preferably 100 mm to 200 mm) having a side length of 50 mm to 500 mm. It is set. The thickness of the peripheral wall 14 and the top wall 15 is set to 10 mm to 100 mm, preferably 20 mm to 30 mm. The casing 11 is made of a general resin material such as ABS or PP, a metal such as aluminum, FRP, ceramic, or a composite material thereof, and has rigidity enough to prevent deformation due to a stepping or walking load.

  The film-like body 12 is stretched on the other end side, that is, the lower end side of the peripheral wall 14, and forms a space 17 that is closed inside the housing 11. The material of the film-like body 12 is made of a resin material such as TPO (thermoplastic elastomer), PVC, PE, thermoplastic polymer, silicon rubber, rubber, or a composite material thereof. The thickness of the film-like body 12 is set to 0.2 mm to 5 mm, preferably 0.5 mm to 2 mm, and is provided so that sound energy can be consumed by internal loss when sound enters. The film-like body 12 is placed in an unfixed state without being bonded to the installation surface F and is in surface contact with the installation surface F, and can vibrate by sound incident on the sound absorber 10.

  Therefore, according to the first embodiment, the film-like body 12 is covered from the upper side by the casing 11 without being exposed, and the deformation of the film-like body 12 due to the use of the sound absorber 10 over time Damage can be avoided and the sound absorbing action by the film-like body 12 can be obtained stably for a long period of time.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals as necessary, and the description is omitted or simplified.

  In the sound absorber 10 of the second embodiment, a sheet-like porous material 20 is provided on the top surface of the top wall 14. The thickness of the porous material 20 is set to 30 mm or less, preferably 5 mm to 10 mm. The porous material 20 is made of a material having a capillary tube such as fibers such as a nonwoven fabric or a material having open cells such as a foam, and when sound is incident, the sound waves are rubbed against the peripheral wall in the pores. Part of the sound energy can be consumed as heat energy by, for example, viscous resistance and vibration of material fibrils. In FIG. 2, the porous material 20 is a single sheet material, but the porous material 20 may be provided for each sound absorber 10.

  According to such 2nd Embodiment, not only the sound absorption performance by the sound absorber 10 of 1st Embodiment but the sound absorption performance by the porous material 20 comes to be acquired now. As a result, it is possible to expand the sound range in which a good sound absorbing effect is obtained, and it can be expected that a comfortable sound field is created.

  Examples of the present invention will be described below together with comparative examples.

[Example 1]
In Example 1, the sound absorber 10 having the same form as that of the first embodiment was produced. The planar shape of the housing 11 was a 200 mm × 200 mm square, the membrane 12 was a PVC sheet having a thickness of 1 mm, and the vertical width of the space 17 was 30 mm.

[Example 2]
In Example 2, the sound absorber 10 having the same form as that of the second embodiment was produced. The porous material 20 was a polyester nonwoven fabric having a thickness of 10 mm, and the other conditions were the same as in Example 1.

[Comparative Examples 1 and 2]
The sound absorber of Comparative Example 1 has a configuration in which the film-like body 12 is omitted from the sound absorber 10 of Example 1.
The sound absorbing body of Comparative Example 2 was composed of only the porous material 20 of Example 2.

In evaluating the sound absorbers of Examples 1 and 2 and Comparative Examples 1 and 2, the random incident sound absorption coefficient was used as an evaluation index. The random incident sound absorption coefficient is referred to as a reverberation room sound absorption coefficient, and is calculated from the decay time of the reverberation room when a sound is emitted in the reverberation room and stopped suddenly by a method according to JIS A 1409.
Further, in each of the examples and comparative examples, a PLD (Power Law Decay) correction method (J. Acous. Soc. Jpn.) Is used to estimate and calculate reverberation time under complete diffusion by fitting a theoretical equation to a curved reverberation decay waveform. E) 19, 5 (1998) 315-326), and the Deep-well method (J. Acous. Soc. Jpn. (E) for suppressing the area effect by installing an acrylic plate enclosure (Deep well) around the material. 19, 5 (1998) 327-338).
In each example and each comparative example, as shown in FIG. 3, the volume (V) 64 m ³ , surface area (S) 100 m ² , V / S = 0.64, approximately in the center of the floor 30a of the reverberation chamber 30. The sound absorber 10 of each Example and each comparative example having a size of 1 m in length and 1 m in width is installed, and a diffusion frame plate 32 having a height of 800 mm made of an acrylic plate having a thickness of 20 mm is installed around the sound absorber 10. did. The sound source 33 is disposed at a position away from the sound absorber 10. In this way, sound (air vibration due to sound) is incident on the surface 10a of the sound absorber 10 from a random direction.
The results of the sound absorption coefficient of each example and each comparative example are shown in the graph of FIG.

The greater the sound absorption rate, the better the sound absorption performance. However, in actual physical sensation, if the sound absorption rate is 0.40 or more, the effect can be realized and it can be said that the sound absorption performance is good.
Here, in the graph of FIG. 4, when looking at the center frequency at which the sound absorption coefficient is 0.40 or more in the middle and low range of about 250 Hz, Examples 1 and 2 are 200 Hz to 315 Hz, and Comparative Example 1 is only 315 Hz. In Example 2, the sound absorption coefficient does not exceed 0.40 in the middle and low range. That is, it can be understood that the sound absorption performance of Examples 1 and 2 is better than that of Comparative Examples 1 and 2 in the middle and low range. Further, in Example 2, the sound absorption rate is near 0.40 or 0.40 or more, not only in the above-mentioned mid-low range, but also at a frequency of 630 Hz or more, and the sound absorption performance in the high range is also good.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this.
That is, the present invention has been particularly shown and described with respect to specific embodiments, but the embodiments and examples described above are not deviated from the technical idea and scope of the present invention. On the other hand, those skilled in the art can add various modifications in shape and other detailed configurations.

  For example, the orientation of the installation surface F may be changed, and may be a wall surface or a ceiling surface. When the installation surface F is a wall surface, the film-like body 12 is installed so as to be in surface contact with the wall surface by rotating 90 ° in FIGS. 1 and 2, and when the installation surface F is a ceiling surface, FIG. , 2 is turned upside down.

  Moreover, in 2nd Embodiment, the installation location of the porous material 20 may be provided in the inside of the housing | casing 11, or may be provided in both the inside of the said housing | casing 11 and on the top wall 14. FIG.

The schematic cross-sectional view which represented typically the sound-absorbing structure which concerns on 1st Embodiment. The cross-sectional view similar to FIG. 1 of the sound absorbing structure according to the second embodiment. Explanatory drawing of the reverberation room which measures a sound absorption coefficient. The graph showing the sound absorption rate of Examples 1, 2 and Comparative Examples 1, 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Sound absorption body, 11 ... Housing | casing, 12 ... Membrane, 14 ... Perimeter wall, 15 ... Top wall, F ... Installation surface

Claims (2)

In a sound absorbing structure in which a sound absorbing body having a rigid housing and a film-like body provided in the housing is provided on the installation surface,
The housing includes a peripheral wall standing from the installation surface, and a top wall that is connected to one end side of the peripheral wall and is spaced a predetermined distance from the installation surface, and opens the installation surface side.
The sound absorbing structure, wherein the film-like body is stretched on the other end side of the peripheral wall and is placed on an installation surface so as to be vibrated by sound incident on the sound absorbing body.   The sound absorbing structure according to claim 1, wherein a porous material is provided in the casing and / or on the top wall.

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