JP3544728B2 - Sound absorption structure - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a sound absorbing structure applied to an indoor space having a light transmitting property (light transmitting property) such as a film structure used as various event spaces including sports.
[0002]
[Prior art]
A characteristic of the membrane structure space in the indoor environment is that external light is taken in and the light transmittance is high. When such a space is used for various event spaces such as sports, the reverberation time in the room is too long unless special measures are taken, and the signals and instructions during sports competitions cannot be heard. It will drop significantly. In addition, obstacles such as a loud sound of music performance also occur.
As described above, in order to improve the clarity of room sound in the film structure space, it is necessary to shorten the reverberation time, and for that purpose, a sound absorbing material must be provided in the room. Conventionally, in order to obtain such high sound absorbing properties, a porous sound absorbing material such as glass wool has generally been used as a sound absorbing material.
[0003]
[Problems to be solved by the invention]
However, in the case of the membrane structure space, it is possible to install the sound absorbing material on the wall surface, but it is impossible to install the sound absorbing material on the ceiling surface because of the transparency.
In addition, a method of suspending a sound-absorbing material such as glass wool is used to maintain high light transmittance and obtain sound absorbing power. However, in the case of a suspended sound absorbing body, the sound absorbing material is suspended to obtain a large sound absorbing power. It is necessary to increase the length of the sound absorbing material or to reduce the installation interval to increase the density. In this case, as a problem, there is a problem in that a limit is imposed on the sound absorbing power from the viewpoint of light transmission and a design problem.
As described above, it is difficult for the conventional film structure to have high light transmittance and to increase the sound absorbing performance.
[0004]
Therefore, the present invention has been made in view of the problems of the related art, and an object of the present invention is to provide a sound absorbing structure having a large sound absorbing property while maintaining high light transmittance. .
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in a sound absorbing structure of an indoor space having a light transmitting property such as a membrane structure, a first air layer is provided inside an outer membrane forming the indoor space through a first air layer. It has a first glass cloth provided and a second glass cloth provided inside the first glass cloth via a second air layer.
Here, it is preferable to change the thickness of the air layer because the frequency characteristics of sound absorption are flattened, but it is possible to keep the air layer thickness constant.
The first and second glass cloths are installed on a ceiling surface in the room.
[0006]
[Action]
In the present invention, by using two glass cloths, a large sound absorbing property is obtained while maintaining high light transmittance.
Here, in order to improve the sound absorbing property of the film structure space, it is necessary to install a sound absorbing material in the film structure space. As described above, a porous sound absorbing material such as glass wool is generally used as the sound absorbing material. The porous sound-absorbing material is a sound-absorbing material that utilizes the fact that a porous material has an excellent sound absorbing effect. That is, sound energy is converted into heat energy by vibration and friction and absorbed in pores on the surface and inside of the material.
[0007]
In this porous material, the viscosity of air greatly affects the sound absorption performance, and the sound absorption coefficient is related to the unit area flow resistance (resistance to the flow of air in the material). When the frequency is high, the sound absorption coefficient increases when there is an appropriate flow resistance. Thus, in a normal building, the porous sound absorbing material is effective for obtaining a large sound absorbing coefficient.
[0008]
However, in the case of a membrane structure space or the like, there is a characteristic in the indoor environment that high light transmittance is required, so that a general porous material having a small light transmittance is not suitable for the film structure space. Therefore, in order to obtain a high sound absorbing property without sacrificing the transmitting property in the film structure space, a glass cloth having a high light transmitting property is used as the sound absorbing material. In this case, if a single glass cloth is provided, a medium sound absorbing performance can be obtained but a large sound absorbing performance cannot be obtained due to sound energy passing through the glass cloth.
[0009]
Therefore, in the present invention, the glass cloth is double-installed, and the glass cloth on the back side has a function of increasing the flow resistance, so that the sound absorbing performance is improved and a large sound absorbing performance is obtained.
Specifically, a first glass cloth is provided inside the outer membrane via a first air layer, and further, a second glass cloth is provided inside the first glass cloth via a second air layer. A cross was provided. With this configuration, the glass cloth (first glass cloth) on the back side (when viewed from the room) becomes a resistance material, and an appropriate flow resistance can be obtained as a whole.
[0010]
As described above, in the present invention, by installing the glass cloth twice, a flow resistance corresponding to a porous material is obtained while maintaining high light transmittance, thereby improving sound absorption.
The sound absorption coefficient varies depending on the thickness of the material and the mounting method, but if each glass cloth is installed so that the thickness of the air layer is large at the center and small at the fixed end, the frequency characteristics of the sound absorption coefficient will be reduced. It becomes flat and good sound absorption performance is obtained.
[0011]
【Example】
An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partial sectional view showing a sound absorbing structure of the present invention.
The membrane structure space is formed by the outer membrane 1, and is used as, for example, various event spaces including sports. Inside the outer membrane 1, a glass cloth 3a is provided via an air layer 2a. Further, a glass cloth 3b is provided inside the glass cloth 3a via an air layer 2b. The glass cloths 3a and 3b are fixed by a plurality of fixing members 4 (for example, structural members such as pipes and steel frames).
[0012]
Here, the glass cloths 3a and 3b (glass cloth), which are the inner membranes, are formed, for example, by weaving long fiber glass fibers into threads. The thickness of the air layers 2a and 2b is preferably, for example, about 100 mm to 300 mm or more.
It is desirable that the glass cloths 3a and 3b thus formed doubly formed are respectively installed on the wall surface and the ceiling surface of the membrane structure space.
[0013]
Here, the test results of the reverberation room method sound absorption coefficient when a single-layer glass cloth is used are shown in FIG. In the test, the back air layer was set to 400 mm. The test was performed using glass cloths (1), (2) and (3) having different flow resistances.
Glass cloths (1) and (2) have moderate flow resistance, and glass cloth (3) has low flow resistance. Here, the sound absorption coefficient is the ratio between the value obtained by subtracting the reflected energy from the incident energy and the incident energy when the sound wave is incident on the object, and the reverberation chamber method sound absorption coefficient is measured when measured in the reverberation room. It corresponds to the average value obtained for all angles of incidence. Since the reverberation chamber method sound absorption coefficient is a function of frequency, in FIG. 2, the horizontal axis represents the center frequency, and the vertical axis represents the reverberation room method sound absorption coefficient.
[0014]
When the glass cloth (3) having a small flow resistance is used, it is understood that a large sound absorbing performance cannot be obtained because the sound wave passes through the glass cloth (3). Even the maximum sound absorption coefficient (center frequency around 4 KHz) is less than 0.2.
On the other hand, when the glass cloths (1) and (2) having appropriate flow resistance are used, it can be seen that a certain degree of sound absorbing performance can be obtained. The maximum sound absorption coefficient of the glass cloth (1) (around a center frequency of 3 KHz) is about 0.7. In the case of the glass cloth (2), the maximum sound absorption coefficient (around a center frequency of 3 KHz) is about 0.65. However, it does not reach high sound absorption performance like glass wool.
[0015]
Next, FIG. 3 shows a test result of a reverberation room method sound absorption coefficient when glass wool which is a porous material is used. In this test, the thickness of the glass wool was set to 50 mm, and the back air layer was set to 100 mm.
As is clear from FIG. 3, the maximum sound absorption coefficient (around 500 Hz) is almost equal to 1. On the other hand, when a single-layer glass cloth is used (see FIG. 2), the sound absorption coefficient of the glass cloth (3) is less than 0.1 in the middle range, and is less than 0.1 in the glass cloth (2). It is about 5 and about 0.6 for the glass cloth (3).
[0016]
Next, FIG. 4 shows a test result of the sound absorption coefficient by the reverberation chamber method (a double circle solid line) when a double membrane in which the glass cloths (1) and (2) are installed in a double manner is used.
It can be seen that the characteristics shown in FIG. 4 are similar to the characteristics when glass wool is used (FIG. 3). For example, the sound absorption at a center frequency near 500 Hz is approximately equal to one.
[0017]
From the above experimental results, by installing the glass cloth (3a, 3b) doubly, the sound absorption performance is improved as compared with the case where the glass cloth is installed singly, and glass wool (a representative of high-performance sound absorbing material) is used. It can be seen that a very large sound absorption coefficient equivalent to 32 kg / m ³ ) can be obtained. This is because the glass cloth (3a) on the back side functions to increase the flow resistance (resistance material), and an appropriate flow resistance can be obtained as a whole.
[0018]
In addition, since a glass cloth having high light transmittance is used as the sound absorbing material, high sound absorbing performance can be obtained without sacrificing light transmittance.
The light transmittance of the glass cloth alone is extremely high, for example, 48% for the glass cloth (1) and 34% for the glass cloth (2). Therefore, even when the glass cloths (1) and (2) are combined, it is 16%. % (Approximately 30% in consideration of the light diffusion effect in the double film), and a sufficient transmittance can be obtained.
[0019]
Although the sound absorption coefficient varies depending on the thickness of the material and the mounting method, as shown in FIG. 5, the thickness of the air layers 2a and 2b is not made constant, and the glass cloths 3a and 3b are separated from the air layer 2a. , 2b are fixed with a plurality of fixing members 4 (for example, structural members such as pipes, steel frames, etc.) so that the thickness at the center is large and the thickness at both ends is small. Characteristics.
[0020]
In the above embodiment, the membrane structure is described as an example, but the present invention is not limited to this, and can be applied to other indoor spaces where light transmission and sound absorption performance are required. Further, in the above embodiment, the glass cloth is used as the inner film, but the present invention can be applied to other equivalent materials having the same transmittance and sound absorption as the glass cloth.
[0021]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, high sound absorption performance is obtained, maintaining high light transmittance. In addition, uniform light transmittance can be obtained as compared with the suspended sound absorber, and there is no design restriction. In addition, higher sound absorbing properties can be obtained as compared with a single film. In addition, the installation is simple and the construction is simple, and the cost is low.
[Brief description of the drawings]
FIG. 1 is a partial sectional view showing a sound absorbing structure of the present invention.
FIG. 2 is a view showing test results of a reverberation chamber method sound absorption coefficient when a single-layer glass cloth is used.
FIG. 3 is a view showing a test result of a reverberation chamber method sound absorption coefficient when glass wool which is a porous material is used.
FIG. 4 is a diagram showing a test result of a sound absorption coefficient in a reverberation room method in a case where a glass cloth is double-installed.
FIG. 5 is a partial sectional view showing another sound absorbing structure of the present invention.
[Explanation of symbols]
1 outer membrane 2 air layer 3 glass cloth 4 fixing member

Claims (2)

In a sound absorbing structure of an indoor space having a light transmitting property such as a membrane structure,
A first glass cloth is provided inside the outer membrane forming the indoor space via a first air layer, and a second glass cloth is provided inside the first glass cloth via a second air layer. Each is fixedly provided by a plurality of fixing members,
Each of the plurality of fixing members fixes both the first glass cloth and the second glass cloth,
The thickness of the first air layer and the thickness of the second air layer are provided so as to be large on the center side between the fixing members and small on the fixed end side of the fixing member. Sound absorbing structure. The sound absorbing structure according to claim 1, wherein the first and second glass cloths are installed on a ceiling surface of the room.

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