JP2517845B2 - Underwater sound insulation board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an underwater sound insulation board, and more specifically, for example, a transmitter / receiver of underwater acoustic equipment provided on a ship bottom or the like is provided with noise from an interfering sound source. The present invention relates to an underwater sound insulation plate that effectively prevents incident light.

[Conventional technology]

BACKGROUND ART Conventionally, for example, a transducer (a sonar transducer, a fish finder, a sounding sounder, a telephone, etc.) for underwater acoustic equipment provided on the bottom of a ship, etc. has a propeller provided on the stern side as shown in FIG. Also, a sound insulating plate A is provided in the vicinity of the wave transmitter / receiver S for the purpose of insulating the interference sound from an interference sound source such as an engine.

By the way, in the structure of the conventional sound insulating plate A, the sound insulating plate A is placed between the transducer S and the disturbing sound source B as an obstacle against the propagation of the sound wave Q at a substantially right angle to the sound wave arrival direction.
The transducer S was installed so as to cover it, and an obstructing sound was dealt with by acoustically creating a shadow.

However, in such a conventional method, since the sound wave wraps around due to the diffraction of the sound wave, it is necessary to make the shield width of the sound insulation plate A sufficiently wider than that of the transducer S.

Further, in the case of a low frequency sound wave, since the diffraction of the sound wave is further increased, it is necessary to provide a wider sound insulation plate, and if the installation width is limited, a high sound insulation effect cannot be obtained. There was a problem to say.

[Object of the Invention]

The present invention was devised by focusing on such conventional problems, and its object is to dispose a phase inversion reflector between a transducer and a disturbing sound source substantially in parallel with a sound wave arrival direction. The object of the present invention is to provide an underwater sound insulation plate capable of effectively reducing the interference sound from the interference sound source by canceling the sound pressure of the direct wave of the incoming sound wave and the reflected wave (phase-inverted reflected wave). .

[Structure of Invention]

In order to achieve the above object, the present invention provides an underwater sound insulation plate comprising a sound insulation plate disposed between a wave transmitter / receiver of an underwater acoustic device and an interfering sound source in the vicinity of the wave transmitter / receiver. At least one phase-inverted reflection plate was placed near the wave filter in parallel with the direction of arrival of the disturbing sound so that the disturbing sound from high to low frequencies could be effectively reduced. It is what

Example of Invention

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In addition, in the following description, the same components as those of the above-described conventional example are denoted by the same reference numerals.

FIG. 1 is a layout view of each device embodying the present invention, showing a transmitter / receiver S for underwater acoustic equipment such as a sonar transmitter / receiver, a fish finder, a sounding sounder, and a telephone, and an interfering sound source B. In the meantime, in the vicinity of the transmitter / receiver S, a phase-inverting reflection plate A having a predetermined length is arranged substantially parallel to the arrival direction of the disturbing sound Q.

The phase inversion reflection plate A is, for example, a closed-cell rubber, or a molded rubber in which air or a sponge containing air is enclosed, and is generally used in water.

According to acoustic theory, this means that the intrinsic acoustic impedance of a medium (water or seawater) is ρ ₀ c ₀ (ρ ₀ : density, c ₀ :
Sound velocity) and the specific acoustic impedance of the reflector is ρc
If (ρ: density, c: speed of sound), when ρ ₀ c ₀ > ρ c, the phase of the sound wave is inverted and reflected at the boundary surface. Since ρc of a material containing a large amount of air is significantly smaller than ρ ₀ c _{0 of} water, the material has good performance as the phase inversion reflector A and is an easily available material.

By arranging the phase-inverting reflection plate A configured as described above between the transmitter / receiver S and the disturbing sound source B substantially in parallel with the arrival direction of the disturbing sound Q, the sound source B is transmitted as shown in FIG. One of the sound waves Q from is directly transmitted to the transducer S via the path P1,
The other one is a phase-inverted reflection plate A, which is reflected in a phase-inverted manner, and reaches the transducer S through a path P2.

The combined sound pressure at the wave transmitter / receiver S is the sum of the sound pressures of the paths P1 and P2, and the sound pressure is reduced by canceling the positive and negative.

 The results of this experiment are shown in FIG.

That is, it can be seen that the lower frequency of the sound wave Q (3 KHz) has a wider width of the sound insulation reduction effect area H, and the higher frequency frequency of the sound wave Q (4 KHz) has a narrow width of the sound insulation reduction effect area H.

The sound insulation effect is also related to the length of the phase inversion reflection plate A, and the length is preferably equal to or longer than the sound wave wavelength.

Next, FIG. 4 and FIG. 5 show that a plurality of phase inversion reflectors A are installed between the transmitter / receiver S and the disturbing sound source B substantially parallel to the arrival direction of the disturbing sound Q. The second embodiment and the third embodiment are shown. In the second embodiment of FIG. 4, the sound wave Q passing through the space G of the two phase inversion reflection plates A arranged substantially in parallel is When the distance between the phase-inverted reflector A and the wavelength have an appropriate relationship, the propagation attenuation of the sound wave Q becomes abnormally large or does not propagate below this frequency.

 This frequency is called the cutoff frequency.

If the phase inversion reflection plate A is set so that the cutoff frequency is not more than the desired frequency, the sound wave Q does not pass even if there is a gap.

Also, regarding the outside of the phase inversion reflection plate A, the first
This is similar to the case of the embodiment.

The sound insulation area that integrates the above can be drawn as shown in FIG.

As described above, the present invention provides a sound wave attenuation region on the opposite side of the arrival direction of the interfering sound by installing a single or a plurality of phase-inverted reflectors substantially parallel to the arrival direction of the interfering sound, and It can be used as a sound insulation plate for the wave transmitter / receiver S existing in the area. In such a sound insulation method, the sound insulation plate is effective even if the width of the sound insulation plate is narrower than that of the transducer S, and since the sound insulation plate has a large effect on low-frequency sound waves, if the installation width is limited, for example, the bottom of a ship. It is particularly effective when the lateral width is limited to reduce the fluid resistance, such as the acoustic equipment installed in.

〔The invention's effect〕

As described above, the present invention provides an underwater sound insulation plate in which a sound insulation plate is disposed in the vicinity of the wave transmission / reception device between the wave transmission / reception device of the underwater acoustic device and the disturbing sound source as described above. By arranging at least one or more phase-inverting reflectors in the vicinity in parallel with the arrival direction of the disturbing sound, it is possible to cancel the sound pressure of the direct wave and the reflected wave (phase-inverted reflected wave) of the incoming sound wave. Thus, there is an effect that the disturbing sound from the disturbing sound source can be effectively reduced.

Further, it has an effect that it can be effectively used in a small installation place and that it has a large sound insulation effect against low frequency sound waves.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is an explanatory diagram of the principle of the sound insulation effect, FIG. 3 is an explanatory diagram showing an experimental example, and FIG. 4 is a second embodiment using a plurality of phase inversion reflectors. 5 is a block diagram showing an example, FIG. 5 is a block diagram showing a third embodiment of the present invention, and FIG.
The figure is a block diagram of a conventional phase inversion reflector. A: Phase inversion reflector, B: Interfering sound source, S: Transducer, Q: Interfering sound.

Claims (1)

(57) [Claims] 1. An underwater sound insulation plate comprising a sound insulation plate disposed between a wave transmitter / receiver of an underwater acoustic device and an interfering sound source in the vicinity of the wave transmitter / receiver. An underwater sound insulation plate, characterized in that at least one phase-inverted reflection plate is arranged substantially parallel to the direction of arrival of the interference sound.