JPH07281674A - Silencer of soundproof chamber - Google Patents

Abstract

PURPOSE:To put a soundproof chamber into a sufficient silent state by arranging sound shielding walls in front of the open surface part of the soundproof chamber and outputting the sounds of the antiphase from the phase of the noises to the periph eral parts of these sound shielding walls and silencing the soundproof chamber. CONSTITUTION:The peripheral parts of the sound shielding walls 3 are provided with an active silencer consisting of microphones 5, digital filters 7 and speakers 9 of sound sources for silencing. Plural pieces of the microphones 5 and the speakers 9 are disposed in the positions corresponding to each other on both the front and rear surfaces of the respective sound shielding walls 3. In such a case, the characteristics of the digital filters are so set that the sounds generated by the speakers 9 are diffracted by the sound shielding walls 3 so as to negate the noises propagating in the soundproof chamber 1, i.e., the noises of low-frequencies by sound wave interference. The high-frequency components of the noise heading from the noise source toward the silencing chamber 1 are shut off by the sound shielding walls 3 and the low-frequency components are attenuated by the sound wave interference with the sounds from the speakers 9, by which the sufficient silencing effect is obtd. in the silencing chamber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound deadening device for a soundproof room installed in a factory, a work place or the like.

[0002]

2. Description of the Related Art In a soundproof room installed in a factory, a work place, etc., one surface is open for people to enter and exit, and a sound insulation wall is arranged in front of the open surface.

[0003]

High-frequency sound having a high degree of straightness of sound waves is prevented from propagating to the soundproof room by the sound insulation wall, and the sound insulation wall exerts a sound insulation effect against noise of high frequency components.

However, the low frequency component noise is diffracted so as to wrap around the end of the sound insulation wall and propagates to the soundproof room, and the sound insulation wall does not exhibit a sufficient sound insulation effect against the low frequency component noise. For this reason, in the soundproof room, noise of a low frequency component cannot be obtained to sufficiently suppress the sound.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a muffling device which brings a soundproof room into a sufficiently muffling state.

[0006]

In order to achieve the above-mentioned object, a sound deadening device for a soundproof room according to the present invention has a sound insulating wall disposed in front of an open surface portion of the sound insulating room, and a sound insulating wall is provided around the sound insulating wall to prevent noise. It is characterized by being provided with an active muffling device that outputs a phased sound to muffle the sound.

In this case, the active muffling device may be set to have an active muffling characteristic so as to muffle low-frequency component noise.

[0008]

According to the above-mentioned structure, the sound insulation effect by the sound insulation wall and the sound interference type sound deadening effect by the active sound deadening device
The propagation of noise to the soundproof room is reduced, and the noise level in the soundproof room is reduced.

Since the sound insulation effect of the sound insulation wall is effective against the noise of the high frequency component, the sound insulation wall prevents the noise of the high frequency component from propagating to the soundproof room, and the active silencer exclusively silences the noise of the low frequency component. Therefore, the active muffling characteristic is set to muffle low-frequency component noise.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 and 2 show an embodiment of a sound deadening device for a soundproof room according to the present invention. The soundproof room 1 has a rectangular parallelepiped shape with only one surface open, and a sound insulation wall 3 is provided upright in front of the open surface part.

In the peripheral portion of the sound insulation wall 3, there is provided an active muffling device including a noise detecting microphone 5, a digital filter 7, and a speaker 9 as a muffling sound source.
In the illustrated example, a plurality of noise detection microphones 5 and a plurality of speakers 9 are provided at positions corresponding to each other on both front and back surfaces of the sound insulation wall 3.

An active silencer is disclosed in, for example, Japanese Patent Laid-Open No. 63-56.
As disclosed in Japanese Patent Laid-Open No. 96-96, the noise is collected by the noise detecting microphone 5 and converted into an electric signal, and the electric signal is input to the digital filter 7 and the noise is outputted from the digital filter 7. An electric signal for generating a sound in the opposite phase to is output to the speaker 9, and the speaker 9 outputs a sound in the opposite phase to the noise.

In this case, the characteristics of the digital filter 7 are set so that the sound generated by the speaker 9 diffracts the sound insulation wall 3 and propagates to the soundproof room 1, that is, the noise of the low frequency component is canceled by the sound wave interference. .

In the muffling device having the above-described structure, the transfer function G (ω) from the noise source A to the muffling evaluation point B set in the muffling chamber 1 is expressed by the following equation.

[0015]

[Equation 1] G (ω) = N (ω) + L (ω) · H (ω) · M (ω) (1) where N (ω): Diffuses the noise insulation wall 3 from the noise source A to mute Transfer function until reaching evaluation point B L (ω): Transfer function from noise source A to noise detection microphone 5 H (ω): Transfer function of digital filter 7 M (ω): Silence evaluation point B from speaker 9 Transfer function to G Here, if G (ω) = 0, the noise at the noise reduction evaluation point B disappears.

Therefore, in order to eliminate the noise at the evaluation point B, the transfer function H (ω) of the digital filter 7
Should be set according to the following formula.

[0017]

H (ω) = − {N (ω)} / {L (ω) · M (ω)} (2) When setting the transfer function H (ω), N (ω), L
It is sufficient to obtain (ω) and M (ω) by measurement and calculate H (ω) according to the equation (2).

By setting the transfer function H (ω) of the digital filter 7 in this way, the noise from the noise source A is canceled at the noise reduction evaluation point B in the noise reduction chamber 1.

In the noise traveling from the noise source A to the muffling chamber 1 with the above-described structure, the high frequency component is exclusively shielded by the sound insulation wall 3, and the low frequency component is attenuated by the sound wave interference with the sound from the speaker 9. As a result, a sufficient silencing effect can be obtained in the silencing chamber 1.

Although the present invention has been described in detail above with reference to specific embodiments, the present invention is not limited thereto, and various embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

[0021]

As can be understood from the above description, according to the sound deadening device for a sound deadening chamber of the present invention, the sound deadening wall provides a sound deadening effect, and the active sound deadening device does not provide a sufficient sound deadening effect at a low frequency. The noise of the components is silenced, and the soundproof room is sufficiently silenced by these.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a silencing device for a silencing room according to the present invention.

FIG. 2 is a side view showing an embodiment of a silencing device for a silencing chamber according to the present invention.

[Explanation of symbols]

 1 Soundproof room 3 Sound insulation wall 5 Noise detection microphone 7 Digital filter 9 Speaker

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H03H 21/00 8842-5J

Claims (2)

[Claims] 1. A sound insulation wall is disposed in front of an open surface portion of a soundproof room, and an active sound deadening device is provided in a peripheral portion of the sound insulation wall to output a sound having a phase opposite to that of the noise to muffle sound. Muffler for soundproof room. 2. The sound deadening device for a soundproof room according to claim 1, wherein the active sound deadening device is set to have an active sound deadening characteristic for deadening low frequency component noise.