JPS59222893A - Acoustic board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a sound absorbing plate.

The principle of sound absorption, which aims to absorb sound from the outside, is to attenuate and absorb sound by converting sound energy into thermal energy, mainly using the viscosity of sound absorbing materials. However, since the energy of sound is small, the heat generated by viscosity is also small, so the method of mixing a large mass into the sound absorbing material is not always effective. Some people are clever enough to put grooves and holes of a certain width into sound-absorbing materials, but these have the disadvantage that the sound-absorbing effect changes depending on the frequency of the sound.

That is, in the conventional device, (1) Since the energy of sound is extremely small, the generation of thermal energy due to the difference in mass is not at all large.

Therefore, there is a method of mixing particles with large mass into sound absorbing materials in order to increase the sound absorption effect, but this is not very effective.

■ The sound absorption characteristics change depending on the frequency, so even those with certain grooves and holes have inconsistent performance.

The present invention has been developed in view of the above, and is intended to solve the above problems. The present invention will be explained in detail below.

In order to increase the sound-absorbing effect of sound-absorbing materials, conventional methods have been used to increase the degree of freedom by drilling grooves and holes. The size of this hole corresponds to the frequency of sound to be absorbed, as illustrated in FIG. 1, and a certain size is only effective at a specific frequency. In FIG. 1, (1') is a sound absorbing material, and (2') is a hole.

Therefore, the present invention is characterized in that the sizes of the holes are widely distributed to create a sound absorbing material that is effective against a wide range of sound frequencies. Figure 2 illustrates this, where (1) is the sound absorption benefit;
(2) is a hole. Especially 5 KC~i (] Q K
Aiming for the effect near C, the diameter is 04 to 20 over the entire surface.
It is characterized by randomly distributed holes in the throat area.

”2 Note 5 KC~l Q Q The frequency of KC is the main frequency range for sonar detectors etc. in the ocean, and if the diameter of the hole is less than 0.4n or exceeds 20wn, there will be resonance at frequencies in this range. No sound absorption occurs. Furthermore, the reason why they are provided in a precise random manner is to widen the frequency of resonance and sound absorption (because sound absorption occurs at one frequency for one hole diameter).

The present invention has been described above, but according to the present invention, since the holes of 0.4 to 20wnΦ are randomly distributed over the entire surface, it effectively absorbs sound at any frequency from 5 KG to Io OKC. A sound absorbing board is obtained.

[Brief explanation of drawings]

In the plan views illustrating sound absorbing ins, FIG. 1 is a conventional one, and FIG. 2 is one according to the present invention. (1)...Sound absorbing board, (2)...Ana agent patent attorney Masashi Yoshitake, -24・5, i
. Fig. 1 Fig. O 2 Fig.

Claims (1)

[Claims] (1) Drill holes with a diameter of 0.4 to 20.0 inches throughout the body densely and randomly, mainly 5KG to 1Q [ ] K
A sound absorbing board characterized by effectively absorbing sound of frequency C.