JPS6316521B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a soundproof wall body in which a plurality of sound absorbing materials having a specific air flow resistance are installed side by side with a predetermined air layer in between, with the air flow resistance decreasing closer to the sound source. . BACKGROUND ART As soundproof walls for noise sources such as railways, expressways, and various factories, soundproof walls using a fibrous sound absorbing material made of glass fibers bonded with phenolic resin or the like are widely used. However, soundproof walls using these fibrous sound-absorbing materials tend to absorb moisture such as rainwater, and the release of absorbed moisture is extremely slow, resulting in a significant decline in sound-absorbing properties due to water absorption. It takes a long time for the properties to recover, and since it is fibrous, various measures have been taken to protect the sound absorbing material, such as covering it with a film and placing punched metal on the surface to prevent the fibers from scattering. Therefore, soundproof walls using fibrous sound absorbing materials have many drawbacks and problems. In addition, we have used ceramic sound-absorbing materials made by bonding inorganic solid particles such as lightweight aggregate, silica sand, or crushed ceramics using various binders, and sintered metal sound-absorbing materials made by sintering metal particles. Soundproof walls are also known, but soundproof walls using these sound-absorbing materials have extremely strong peaks in the frequency characteristics of their sound absorption coefficients, and are not necessarily fully satisfactory in terms of sound absorption coefficient for noise over a wide range of frequencies. It wasn't. The soundproof wall body of the present invention was made to solve these drawbacks of conventional soundproof wall bodies, and in particular, the sound absorption coefficient decreases little due to rain and maintains a high sound absorption coefficient over a wide frequency range. It is a soundproof wall with an air flow resistance of 40 to 500 N・s/m ³ formed by fixing inorganic particles or metal particles.
A sound absorbing material is installed on the side facing the sound source, and a sound absorbing material with an air flow resistance of 300 to 1600 N・S/m ³ and having a higher air flow resistance than the sound absorbing material is installed on the side facing the sound source. At least one layer or more than one layer is provided between the sound absorbing material and the sound insulating material with an air layer having a thickness equal to or greater than the thickness of the sound absorbing material immediately before the sound source side, and the sound absorbing material immediately before the sound insulating material is provided in close contact with the sound insulating material. This is a soundproof wall supported by a frame. A more precise configuration of the present invention will be explained based on FIG. 1 showing one specific example. Ceramics, refractories,
Sound absorbing material 1 or nickel made of inorganic particles made of crushed materials such as tiles, or silica sand, perlite, pumice, hollow balloons, lightweight aggregate, etc., fixed and formed using a glass-based binder or a synthetic resin binder. , a sound absorbing material 1 made of a sintered metal made by sintering metal particles such as brass, copper, brass, aluminum, stainless steel, etc., and has an air flow resistance of 40 to 500 N·S/m ³ , preferably 200 to 400N・
S/m ³ of the sound absorbing material 1 on the side facing the sound source;
In other words, it is installed on the sound wave incidence side. The air flow resistance between the sound insulator 2 forming the back surface of the wall and the sound absorbing material 1 on the sound source side installed on the side facing the sound source is 300 to 1600 N·S/m ³ , preferably 700 to
Another sound absorbing material 3 having a resistance of 1300 N·S/m ³ and greater air flow resistance than the sound absorbing material 1 is installed. The sound absorbing material 3 may of course be a so-called ceramic sound absorbing material or a sintered metal sound absorbing material to which the same inorganic particles or metal particles as the sound absorbing material 1 are fixed, but it may also be a fibrous sound absorbing material made of glass fiber or the like. The sound absorbing material 3 is installed with an air layer 4 at least wider than the thickness t of the sound absorbing material 1 on the sound source side between it and the sound absorbing material 1 on the sound source side. The sound insulator 2 and the sound absorbing material 3 facing it are provided in close contact with each other. The outer peripheries of the sound absorbing material 1, the sound absorbing material 3, and the sound insulating material 2 are surrounded by a frame 6 preferably made of aluminum, synthetic resin, or the like. Note that the sound insulating body 2 may be an existing concrete wall, or in the case where the sound insulating wall body of the present invention is formed by stacking sound insulating panels, it may of course be formed of aluminum, synthetic resin, or the like.
Furthermore, the sound insulation body 2 and the frame body 6 may of course be integrally formed of the same material. In the specific example shown in FIG. 1, a case has been described in which one piece of sound absorbing material 3 is installed between the sound absorbing material 1 on the sound source side and the sound insulating material 2, but the sound absorbing material 1 on the sound source side and the sound insulating material 2 are There is not necessarily one sheet (one layer) between
It is not necessary to use only one sound absorbing material, and it is of course possible to install a plurality of sound absorbing materials. However, when a plurality of sound absorbing materials 3 and 5 are installed between the sound absorbing material 1 and the sound insulating material 2 on the sound source side, there is an air layer 4A between the plural sound absorbing materials 3 and 5. 4B, and in such a case, it is preferable that the air layers 4A and 4B have a thickness equal to or greater than the thickness of the sound absorbing material 1 immediately in front of the sound source side of the air layer. Next, the reasons for the limitations of the present invention will be described. Set the flow resistance of the sound absorbing material on the side facing the sound source to 40~
The reason why we limited it to 500N・S/ ^m3 is because the flow resistance is
If it is ^less than 40N・S/m3, the viscous frictional resistance of the air in the pores of the sound absorbing material is too small, so the resistance component of the acoustic impedance density becomes small, and even if a sound wave is incident, there is no friction loss due to the movement of the air. This is due to the small size and poor sound absorption properties, and the air flow resistance.
If it exceeds 500N・S/ ^m3 , the incident sound will be easily reflected on the surface of the sound-absorbing material, resulting in poor sound-absorbing properties.
Furthermore, as shown in FIG. 4, the amount of water absorbed during rain is large and drying is delayed, so that the sound absorption properties in the wet state after rain are greatly inferior. Furthermore, the air flow resistance of the sound absorbing material placed between the sound source side sound absorbing material and the sound insulating material is set to 300 to 1600 N・S/m ³ because the flow resistance is less than 300 N・S/m ³ . This is because the viscous friction loss due to air movement is too small, resulting in poor sound absorption properties, and if it exceeds 1600 N·S/m ³ , the incident sound is likely to be reflected on the surface of the sound absorbing material, resulting in poor sound absorption properties. In addition, the reason why the flow resistance of the sound absorbing material placed between the sound absorbing material on the sound source side and the sound insulating material is made larger than that of the sound absorbing material on the sound source side is because the sound absorption characteristics when this relationship is reversed are as follows: This is because the characteristics of the sound-absorbing material itself are almost equal to those of the sound-absorbing material alone, which reduces the effect of improving the sound-absorbing characteristics of the present invention. The reason why the distance between the material and the material is set to be equal to or greater than the thickness of the sound absorbing material on the sound source side is as follows.
This is because if the interval dimension is less than the thickness, the effect of improving sound absorption properties will be reduced. Next, the effects of the present invention will be explained based on examples of the present invention. Example 1 Sound absorbing materials having the wall thicknesses, flow resistances, and normal incidence sound absorption coefficients shown in Table 1 were prepared and combined as shown in Table 2 to form soundproof wall bodies No. 1 to No. 14 of the present invention. water at a rate of 550 c.c./min in dry condition and on the sound absorbing material on the sound source side.
After being sprayed for 20 minutes and left in a room at a temperature of 20°C and a humidity of 60% for 1 hour, the peak sound absorption coefficient in a "wet state" and the average sound absorption coefficient between frequencies of 500 and 2 kHz were determined for comparison. The results are shown in Table 2. Note that, as reference products, soundproof wall bodies No. 15 to No. 25 were made with combinations outside the numerical limit range of the present invention, and the same measurements as above were performed on these as well, and the results are listed in Table 2.

【table】

[Table] As is clear from these results, the soundproof wall of the present invention shows relatively little decrease in sound absorption coefficient even in wet conditions after rain, and has high sound absorption characteristics over a wide frequency range. It was confirmed that the reference product had a significant decrease in sound absorption coefficient. As described above, the soundproof wall body of the present invention includes a plurality of sound absorbing materials having different air flow resistances, which are arranged side by side with a predetermined air layer in between so that the air flow resistance becomes smaller toward the sound source side, and A sound absorbing material ³ in which a sound absorbing material to which inorganic particles or metal particles are fixed is placed on the sound source side and has an air flow resistance of 300 to 1600 N・S/m3, which is greater than the sound source side sound absorbing material 1. At least one layer or more than one layer is provided between the sound absorbing material 1 on the sound source side and the sound insulating material 2 with an air layer 4 having a thickness greater than the thickness of the sound absorbing material immediately before the sound source side, and the sound absorbing material 3 immediately before the sound insulating material is Since it is installed closely to the sound insulation body 2, it is possible to provide a sound insulation wall that has little reduction in sound absorption coefficient due to rainfall and maintains a high sound absorption coefficient over a wide frequency range, and is especially suitable for railways, expressways, various factories, and power substations. It is useful as a soundproof wall for outdoor noise sources such as places, and is also extremely useful for preventing noise pollution.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of one specific example of the soundproof wall body of the present invention, Fig. 2 is an explanatory diagram of a different specific example of the soundproof wall body of the present invention, and Fig. 3 is a drying of sound absorbing materials with different air flow resistances. Explanatory diagram showing sound absorption characteristics in various states, 4th
The figure is an explanatory diagram showing the relationship between flow resistance and water absorption amount of the front particulate sound absorbing material. 1, 3, 5...Sound absorbing material, 2...Sound insulator, 4, 4A,
4B...air layer, 6...frame body.

Claims (1)

[Claims] 1 A sound absorbing material 1 formed by fixing inorganic particles or metal particles with an air flow resistance of 40 to 500 N・S/m ³ is installed on the side facing the sound source, and a sound absorbing material 1 with an air flow resistance of 300 to 1600 N・S/m 3 is installed on the side facing the sound source. /m ³ and has greater air flow resistance than the sound absorbing material 3.
is provided between the sound absorbing material 1 on the sound source side and the sound insulating material 2 with an air layer 4 having a thickness greater than or equal to the thickness of the sound absorbing material immediately before the sound source side, and at least one layer or more of the sound absorbing material immediately before the sound insulating material. 3 is provided closely to the sound insulating body 2, and these are supported by a frame 6.