JPH03161603A - Sound attenuation wall - Google Patents

Abstract

PURPOSE:To improve sound-insulating and sound-absorbing effects by partitioning the inside of a wall body into a plurality of compartments by bulkhead plates, coating the whole of the inner side faces of the compartments with vibration-proof sound-absorbing paints and covering the opening section of the wall body with an acoustical board having sound-absorbing holes. CONSTITUTION:The inside of a wall body 1 formed of a rigid material such as a metallic plate, a plastic board, a wood board, an inorganic material, etc. is partitioned by bulkhead plates 2, thus shaping a plurality of compartments. The whole of the inner side faces of each compartment is coated with vibration- proof sound-absorbing paints 7 formed by mixing and uniformly dispersing metal powder or the powder of a heavy mass substance. The opening surface of the wall body 1 is covered with an acoustical board 3 to which a large number of sound-absorbing holes 6 are shaped. Accordingly, the effect of a coincidence effect can be prevented completely.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a sound deadening wall.

[Prior Art and Considerations Leading to the Invention] Generally, a soundproof wall consists of a metal plate that forms a package, and inside the package, a sound absorbing material such as a fiber mat or foam is covered with a vinyl chloride film. The structure used is that the inner part is wrapped with polyethylene film or the like. Soundproof walls with the above structure are installed in the form of screens on both sides of expressways and Shinkansen lines, but there has been a limit to their soundproofing effectiveness.

This is because the structure of soundproof walls is designed to insulate and absorb sound.

Next, this will be explained in detail. Steel plates are usually used for the casing of soundproof walls. This is called the mass penalty (the transmission loss of a wall made of an airtight, uniform material is proportional to the logarithm of the product of its mass per unit area and the sound frequency. This is called the mass penalty for transmission loss).
) is based on the principle of In other words, the use of steel plates seems to be optimal for sound insulation. However, this seemingly optimal steel plate also had weaknesses. This is due to the coincidence effect (when sound enters a wall obliquely in a certain frequency range, there is a phase difference in the sound pressure depending on the position on the wall, which causes forced bending vibration along the wall, and along this vibration wave This is because it has the disadvantage of being affected by the phenomenon that allows sound to pass through (a phenomenon that makes it easier for sound to pass through). About sound absorption of porous sound-absorbing materials (1) Glass wool, Rosoku wool, and open-cell materials have many small gaps in the material and are breathable, so sound waves (longitudinal waves) propagating through the air are passes through it. At that time, friction and other factors convert it into thermal energy, creating a sound absorption effect. (2) The degree to which a sound-absorbing material absorbs sound is indicated by its sound absorption coefficient (α), which is generally defined as follows. (3) A feature of porous sound-absorbing materials is that they absorb mid-to-high frequencies, but the sound absorption coefficient decreases as the frequencies become lower. Also, when these sound absorbing materials come into direct contact with a hard wall or board, their effectiveness becomes extremely small because there is no air space behind them. This is because sound absorption includes transmitted sound, and there is also an air layer (
In the case of a soundproof wall, it is necessary to install an air chamber (an air chamber behind the sound absorbing material). It is also to prevent the influence of standing waves. As mentioned above, the relationship between sound absorption and transmitted sound is inseparable.
In order to clearly increase the sound absorption effect by this,
It is necessary to increase the thickness of the sound absorbing material. However, the thickness of the soundproof wall is also limited by usage conditions. Therefore, five of the commonly used soundproofing materials are
? With a thickness of CI1, we cannot expect a good sound absorption effect. If possible, 35CI1 or more is desirable. This means that if the center of the noise is at a frequency of 1 kHz, the wavelength is 34c.
m (calculated from the speed of sound). In fact, such a thickness cannot be achieved due to space constraints, and the thickness of the soundproof wall itself is generally around 10 cm.

If the sound absorption fails, it is considered to be a sound insulation effect, but if you expect sound insulation power, the reflected resonance sound will become louder.

Depending on the conditions, the sound energy of resonance can be so powerful that it can be amplified ten times. In addition, the soundproof walls installed on private carriageways have height restrictions and are open at the top, so when sound waves are projected onto the wall, they are diffracted not only by the wall, but also by the top of the soundproof wall and emitted. It makes a sound. The above is the current state of general soundproof walls. The present invention was completed by considering these points, and is a soundproof wall formed to exhibit soundproofing and silencing effects.

[Means for solving problems]

In this invention, the inside of a wall (1) formed of a hard material such as a metal plate, plastic, wood board, or inorganic material is replaced by a partition plate (2).
) and apply a paint made by mixing and uniformly dispersing metal powder or heavy figurine powder to the entire inner surface of the divided compartment, and then apply a paint formed by mixing and uniformly dispersing powder of metal powder or heavy figurines, and then divide the opening surface of the coated wall into multiple This is a sound-absorbing wall that is covered with a sound-absorbing plate with holes formed in it. [Example] The inside of the wall body (1) is divided into a lattice shape with partition plates (2) to form a plurality of compartments, and the entire inner surface of the compartments is coated with metal powder or heavy material powder. Vibration and soundproofing effects can be obtained by applying a coating formed by uniformly dispersing the mixture. Examples of metal powder include lead, aluminum, zinc, iron,
Metal powders such as tin, brass, copper, ferrite, permalloy, nickel, etc. Preferable binders for paints include synthetic resins melted in organic solvents, water-based emulsions, and oil-based binders. Furthermore, the paint applied to the inside of the compartment may be a vibration-proof and sound-proof paint, which has a large vibration and soundproof effect. This is because when this paint vibrates due to sound pressure,
Frictional heat is generated at the interface between the resin and metal powder, and the heat is dissipated by diffusion. Therefore, the purpose is to reduce sound by converting sound energy into thermal energy. The wall (11) coated with the paint (7)
Fix the sound absorbing board (3) on top of it.

A plurality of sound absorbing holes (6) are formed in the sound absorbing plate <<3>>.

The sound absorption holes (6) are formed in a grid pattern at equal intervals vertically and horizontally or in a staggered manner. The diameter of the sound absorption holes is preferably around 7 to 10 ml, and the vertical and horizontal pitch intervals are preferably around 20 to 25 mm. The sound absorbing board formed in this way is superimposed on the wall (11) formed by applying the anti-vibration and sound-insulating paint as described above, and is firmly fixed with screws (4") in the screw holes (5). ．If the sound-absorbing wall constructed in this way is installed in the form of a screen on both sides of a motorway or Shinkansen track where noise is generated, it will have a structure that provides soundproofing only by absorbing ε sound and sound, like conventional soundproofing walls. Differently, the one of the present invention becomes a sound-absorbing wall that changes the frequency of the reflected sound reflected within the wall and the frequency of the projected sound projected onto the wall surface, causing the sound waves to interfere with each other and eliminate it. creates a phase difference by changing the frequencies of both.In other words, if the frequencies of the reflected sound and the projected sound are changed and a shift (difference) of 1/4 wavelength is created, the peaks and troughs of the sound waves overlap, causing interference. The sound waves are generated and the sound waves are canceled out.This is noise reduction due to the interference effect of sound waves.

The sound-absorbing walls of the present invention are erected on both sides of the highway, and when the projected sound waves enter the wall surface, the sound-absorbing holes (6) of the sound-absorbing plate (3)
is attenuated by When it receives sound waves, the circumference of the hole causes a contraction movement (xpangu).

The energy consumption required for this movement becomes damping force. When the sound waves attenuated by the sound absorption holes enter the wall through the holes, vibration-proof and sound-proofing paint (paint formed by mixing and dispersing metal powder or heavy material powder, especially desirable paint is It is attenuated by the damping force of the anti-vibration and sound-insulating paint (No. 62-58633). Moreover, the wall (1) is divided by partition walls {2}, and the upper part is covered with a sound-absorbing plate (3) to form a resonator. Therefore, the projected sound waves have internal interference (
There is a phase difference of 174 in both sound waves, and the peaks and troughs of the sound waves overlap, causing the sound to disappear). In this way, the partition plates form a collection of resonators inside the wall, so the sound deadening effect is extremely large. Furthermore, the anti-vibration/sound-proof paint (paint with uniformly dispersed metal powder) that is applied does not have frequency characteristics to promote this interference effect. Therefore, the damping force acts uniformly over all frequencies. However, simply having a large number of resonators does not necessarily mean that it is good. There are standards for the size (dimensions) of the box. In other words, the standard frequency of noise is generally 1 kHz. This sound has 34 wavelengths (calculated from the speed of sound). Therefore, it is desirable to use this as a standard for the dimensions (length and width) of the box. When formed in this way, the effect of preventing reflected sound is extremely strong. Therefore, the sound-absorbing wall of the present invention can be used not only as a sound-proof wall as described above, but also by installing it on the ceiling or wall of a large theater, music hall, etc. and covering the surface with cloth to prevent reflected sound and obtain a comfortable acoustic effect. .

〔Effect of the invention〕

The soundproofing wall of the present invention has the same soundproofing effect as the conventional soundproofing wall, that is, it has a uniform soundproofing effect.
In addition to the sound absorption effect, the projected sound is also canceled by the interference effect as described above. Therefore, the effect of attenuating reflected sound is large. Also, since the steel plate coated with soundproofing paint has no frequency characteristics, it is not affected by the coincidence effect at all. Therefore, the return sound effect is also extremely large.

As described above, according to the present invention, a sound-absorbing wall with extremely excellent soundproofing ability was obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the inside of the wall structure of the sound-absorbing wall of the present invention;
FIG. 2 is a sound-absorbing plate mounted on the wall shown in FIG. 1, and FIG. 3 is an assembled view of the sound-absorbing wall. ■...Wall body 2...Partition plate 3...Sound absorption board 4...Sound absorption board mounting hole...Sound absorption board fixing screw 5...Screw hole 6...Sound absorption drilled in the sound absorption board Hole 7: Applied anti-vibration and soundproof paint

Claims (1)

[Claims] (1) The interior of the wall (1) made of hard materials such as metal plates, plastics, wooden boards, and inorganic materials is divided by partition plates (2), and metal powder is applied to the entire inner surface of the divided compartment. Or, a sound-absorbing wall characterized by applying a paint formed by mixing and uniformly dispersing powder of a heavy substance, and covering the open surface of the applied wall with a sound-absorbing plate having a plurality of holes.