JPH0546180A - Sound absorber - Google Patents

Abstract

(57) [Summary] [Object] To provide a sound absorbing body having excellent sound absorbing characteristics in a wide frequency range by using a sound absorbing body having a multilayer structure. [Structure] A sound wave 6 is incident on a first layer 1 through which air can pass, part of which is absorbed by vibration of the first layer 1, and the rest passes through a sound absorbing material 2 and is absorbed as a sound wave 6 '. . The remaining sound wave 6 ′ is absorbed by the resonance of the second layer 3. [Effect] Since the vibration of the first layer and the first sound absorbing material absorb sound in the mid-high range, and the resonance of the second layer absorbs sound in the low range, excellent sound absorbing characteristics can be obtained over the entire band.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing body having excellent sound absorbing performance in the whole range from low sound range to high sound range.

[0002]

2. Description of the Related Art In recent years, along with the improvement of living environment, attention has been paid to measures against external noise such as traffic noise and noise from neighboring houses. Therefore, construction of sound absorbing materials for construction is simple, high performance and inexpensive. It has been demanded.

Conventionally, as the sound absorbing material, fiber materials such as glass wool, rock wool and felt, porous materials such as soft urethane foam, and plate materials such as gypsum board and perforated hard board are used.

[0004]

However, the above-mentioned fibrous materials and porous materials do not have sufficient sound absorbing performance in the low frequency range, and the thickness of the sound absorbing material must be increased in order to absorb the low frequency range. There is. Further, the plate-shaped material that absorbs sound by utilizing the plate resonance absorbs only the sound in the vicinity of the resonance point, and is therefore not suitable as a sound absorption material in the entire band.

In view of the above problems, the present invention provides a sound absorbing body having excellent sound absorbing characteristics over a wide frequency band.

[0006]

In the sound absorbing body of the present invention, a first sound absorbing material is arranged on the back surface of the first layer through which air can pass.
A multilayer structure in which a second layer that does not allow air to permeate is provided on the back surface of the first sound absorbing material, and a sealed space filled with the second sound absorbing material is provided on the back surface of the second layer. ing.

[0007]

According to the present invention, by the above-described structure, the resonance of the first layer and the sound absorption of the first sound absorbing material absorb the sound in the mid-high range and the resonance of the second layer whose resonance is set in the low range. Since it can absorb sound in the low frequency range, it has excellent sound absorption characteristics over the entire band.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sound absorber according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a sound absorbing body in one embodiment of the present invention. 1 is a first layer through which air can permeate, 2 is a first sound absorbing material arranged on the back surface of the first layer 1, and 3 is a perimeter fixed to a cabinet 5 for sealing the back surface and is impermeable to air Second layer, 4 is second sound absorbing material, 6
Is a sound wave.

In the sound absorber constructed as described above, first, the sound wave 6 is incident on the first layer 1 through which air can pass, part of which is absorbed by the vibration of the first layer 1, and the rest is the sound absorbing material. 2 and is absorbed as a sound wave 6 '. The remaining sound wave 6 '
Is absorbed by the resonance of the second layer 3, so by limiting the resonance frequency of the second layer 3 to the low frequency range, the sound absorption performance is excellent over a wide range of frequencies as compared with the conventional single-material sound absorber. Is obtained.

The air-permeable first layer 1 may be a woven or non-woven fabric made of natural or synthetic fibers or a polymer sheet having a large number of pores, and the fibers may be electrostatically coated on the adhesive layer. A layer such as a flocked coating film that provides some resistance to the flow of air is suitable and can be used in any case. In particular, a porosity of about 5 to 20% is suitable as a measure of air permeability. When it is 20% or more, the sound absorption effect due to the vibration of the first layer is decreased, and conversely, it is 5
When it is less than%, the ratio of reflection of the sound wave 6 increases, and the sound absorption characteristic in the middle and high-pitched sound range deteriorates.

The first sound absorbing material 2 and the second sound absorbing material 4 are fiber sound absorbing materials such as glass wool and rock wool which have been conventionally used, or soft urethane foam, aluminum foam, and ceramic foam depending on the purpose. Any porous sound absorbing material such as a body may be used. Further, as the second layer, a plate material such as a wood plate or a metal plate may be optimally designed in terms of thickness and rigidity to set a target resonance frequency (a frequency at which sound is to be absorbed). Further, as shown in (FIG. 2), the resonance point of the vibration system is designed even in the structure in which the second layer 3 is supported by the spring 7 and the periphery is fixed to the cabinet 5 by the edge 8 formed of cloth or the like. As a result, the same effect can be obtained.

[0013]

As described above, according to the present invention, the first sound absorbing material is arranged on the back surface of the first layer through which air can permeate, and the back surface of the first sound absorbing material does not permeate air. The second layer is provided, and the back surface of the second layer is a sound absorbing body composed of a multilayer structure in which a closed space filled with a second sound absorbing material is provided. Since the first sound absorbing material can absorb sound in the mid-high range and also in the low range due to the resonance of the second layer, the sound absorbing characteristics can be excellent over the entire band. Further, since the resonance frequency of the second layer can be arbitrarily set, it is possible to easily obtain the sound absorption characteristic according to the purpose.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a sound absorbing body according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a sound absorbing body according to another embodiment of the present invention.

[Explanation of symbols]

 1 1st layer 2 1st sound absorbing material 3 2nd layer 4 2nd sound absorbing material 5 Cabinet 6,6 'Sound wave 7 Spring 8 Edge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuei Sato 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A first layer on a back surface of the first layer permeable to air.
Sound absorbing material is arranged, a second layer impermeable to air is provided on the back surface of the first sound absorbing material, and a closed space filled with the second sound absorbing material is provided on the back surface of the second layer. A sound absorber characterized by being arranged. 2. The sound absorbing body according to claim 1, wherein the opening ratio of the first layer is about 5 to 20%. 3. The second layer supported by a spring,
The sound absorbing body according to claim 1, wherein a structure is provided in which the periphery of the layer is fixed to a cabinet that seals the second sound absorbing material with a support member.