JPH09269788A - Acoustic door - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrier-free open type acoustic door making the circulation of air free and interrupting the passing of a sound wave radiated from a noise sound source by controlling the diffusing of a sound with an opposite phase sound wave radiating speaker, a sound absorbing wall, and a sound absorbing muffler. SOLUTION: This acoustic door is provided with a waveguide part 1 controlling the progressing direction of the sound weave radiated from a noise source and opening parts 2 whose opening directions are different from that of the waveguide part 1 and a sound absorbing wall 3 on which the sound passing through the waveguide 1 strikes is provided ahead the progressing direction of the sound wave and opposite phase sound wave radiating speakers 5 are provided in vicinities of edges 4 at which the sound wave passing through the waveguide part 1 are diffracted into the opening parts 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an acoustic acoustic device which restricts diffusion of sound by an anti-phase sound wave emission speaker and a sound absorbing wall or sound absorbing muffler, allows free circulation of air, and blocks passage of sound waves emitted from a noise source.・ It is about doors.

[0002]

2. Description of the Related Art Conventionally, an active muffler for reducing noise by radiating a sound wave having the same sound pressure and a phase opposite to that of a sound wave emitted from a noise source from a speaker to reduce the noise is known as an air conditioner. There have been variously devised and put into practical use as ducts, interiors of automobiles, refrigerators and earphones, and automobile exhaust systems.

[0003]

The sound deadening by the above-described active sound deadening device is such that the sound field for sound deadening is one-dimensional duct sound deadening, one-point space near the ear, or three-dimensional sound field Even in the case of muffling, it is often a limited narrow space. The range of the sound to be muted is
Many of them deal with periodic noise in a relatively long wavelength and low frequency band of 500 Hz or less, and in many cases, the type of noise source, the frequency band, the size of the silencing process space, etc. are greatly limited.

According to the present invention, of the noise that passes through the waveguide portion 1 set to an arbitrary size, the direct wave is absorbed by the sound absorbing wall 3 and the sound absorbing muffler 7, and the edge 4 is diffracted into the opening 2. The secondary wave thus diffused is effectively silenced by the anti-phase sound wave emission speaker 5, and the handleable range of the noise source can be expanded to a high frequency band of 1000 Hz or higher. It is intended to provide a practical acoustic door capable of increasing the size of the waveguide part 1 and the opening part 2 which are subjected to noise reduction processing and become barrier-free to any size.

[0005]

A waveguide section 1 for limiting a traveling direction of a sound wave radiated from a noise source and an opening section 2 having an opening direction different from that of the waveguide section 1 are provided. A sound absorbing wall 3 that absorbs sound waves is provided in front of the traveling direction of the sound waves that pass through, and a negative-phase sound wave emission speaker 5 is provided in the vicinity of an edge 4 where the sound waves that have passed through the waveguide section 1 are diffracted into the opening section 2. Set up. The angle formed by the opening directions of the waveguide 1 and the opening 2 is such that a sound wave traveling straight along an arbitrary straight line in the waveguide 1 passes straight on the same straight line and the opening 2 is formed. It is good to make it an angle that cannot pass through.

The ratio of the length and the width of the sound emitting port is set to 1
The outer edge in the length direction of the sound wave emission port of the speaker, which has an elongated shape of about 0 to 1, and whose length does not exceed 1/2 wavelength of the maximum frequency of the sound wave emitted by the speaker, is the edge 4 described above. The sound wave emitted from the noise source is directed in the direction in which the sound wave emitted from the noise source passes through the waveguide 1.

In addition, in all or part of the sound absorbing wall 3,
The sound absorbing muffler 7 is used.

[0008]

The direct wave radiated from the noise source and passing through the waveguide portion 1 is absorbed by the sound absorbing wall 3 and the sound absorbing muffler 7 having a high sound absorbing property provided in the forward direction, and is not diffused again as a reflected wave. Is done.

Of the direct waves passing through the waveguide 1, the sound wave passing near the edge 4 is a new secondary wave front as a linear sound source whose source is an infinite number of points on the edge 4. Are formed, the direction of the propagation direction is changed as a diffracted wave, the light diffracts into the opening 2, and is diffused two-dimensionally. The area where the diffracted wave serves as a linear sound source and the wavefront spreads two-dimensionally is a sound area in which the propagation state of sound waves is clear, and a space in which the silencing control by sound wave interference can be efficiently performed is set in the opening 2. be able to.

With respect to the secondary wavefront in which the propagation state as the wave of the sound wave is specified, the speaker is radiated in the lengthwise direction to the source of the secondary wavefront, that is, in the vicinity of the edge 4 serving as the source wave source. Install a speaker with long and narrow sound wave emission holes whose size does not exceed 1/2 wavelength of the maximum frequency of the sound wave to be connected to the length direction in a required number so that the length matches the length of the edge 4. And then the opposite phase of the diffracted sound,
Emits a sound wave of approximately the same sound pressure that serves as a linear sound source. The wavelength and amplitude of the secondary wavefront are exactly the same as those of the wavefront with the same phase, and the wavefront with the same phase is connected to the secondary wavefront in antiphase. When the sound and the sound waves are caused to interfere with each other, the two sound waves consume energy as waves and mutually cannot continue the propagation of the sound waves, and the propagation of the sound waves is blocked.

[0011]

【Example】

Example 1 An acoustic door according to the present invention is shown in FIGS.
And it demonstrates with reference to FIG. FIG. 1 is a view showing the arrangement and operation when an acoustic door according to the present invention is used in an opening of a soundproof room for preventing noise on the noise source side, and FIG. 2 is a perspective view of the soundproof room opening. 3A and 3B are views showing the arrangement and action when the acoustic door according to the present invention is used for the opening on the sound receiving side. 1, 2, and 3, 1 is a waveguide portion, 2 is an opening portion, 3
Is a sound absorbing wall, 4 is an edge, 5 is a negative-phase sound wave emission speaker, 6 is a sound absorbing and insulating wall, S is a noise source, and W is a secondary wave front.

Referring to FIG. The sound wave generated by the noise generated in the soundproof room for preventing the diffusion of the noise passes through the waveguide section 1 with its traveling direction restricted by the sound absorbing / insulating wall 6 constituting the waveguide section 1. The sound wave that has passed through the waveguide 1 travels toward the front sound absorbing wall 3 and is absorbed by the sound absorbing wall 3 having a high sound absorbing property.

On the other hand, the sound wave that has passed through the waveguide section 1 and has reached the vicinity of the edge 4 forms a new secondary wave front by using the infinite number of points on the edge 4 as the source of the elementary wave, and diffracted wave. As, it goes around into the opening 2. The diffracted wave at this time becomes a linear sound source as a collection of an infinite number of points on the edge 4, and spreads two-dimensionally.

The edge 4 is the length of the sound emitting port, and
A speaker with a width ratio of about 10 to 1 and a length not exceeding 1/2 wavelength of the maximum frequency of the sound wave emitted by the speaker is installed from the noise source in the opening direction of the sound wave emission port. By arranging the radiated sound waves in the direction in which they pass through the waveguide 1 so that the outer edges in the length direction of the sound wave emission port are connected in the required number according to the length of the edge 4 It is configured.

The anti-phase sound wave emission speaker 5 detects a sound wave propagating in a fixed direction in the vicinity of the speaker with a sensor microphone and propagates a sound wave having a phase and an acoustic pressure opposite to that of the detected sound wave in a propagation state of the original sound wave. It radiates instantly with the timing. The secondary wave diffracting the edge 4 and the sound wave radiated from the antiphase sound wave emission speaker 5 are both line sound sources, and the positions of the respective line sound sources are close to each other. Sound waves interfere with each other without being greatly affected by the phase shift, and the propagation energy is efficiently reduced.

In the space provided by the opening 2, the propagation energies of the halved sound waves of the direct wave passing through the waveguide section 1 and the secondary wave diffracting around the edge 4 are greatly increased. This is an area where the air flow is free and the sound waves emitted from the noise source do not pass.

Referring to FIG. Of the external noises whose traveling direction is restricted by the sound absorbing / insulating wall 6 forming the waveguide portion 1 and passing through the waveguide portion 1, the direct wave is absorbed by the sound absorbing wall 3 having a high sound absorbing property in the front of the traveling direction, and the edge 4 The secondary wave diffracted by is subjected to acoustic interference by the antiphase acoustic wave emission speaker 5 and is silenced, so that external noise cannot pass through the opening 2. The opening 2 on the sound receiving side is made barrier-free to cut off only the passage of noise.

Second Embodiment A second embodiment will be described with reference to FIG. FIG. 4 is a principle view showing an operation when the acoustic door of the present invention is used for an opening portion of an air conditioning duct, and portions common to FIG.
The same reference numerals are given. The direct wave that has passed through the waveguide 1 is
The secondary wave that is absorbed by the sound absorbing wall 3 having a high sound absorbing property at the front side and is propagated by diffracting the edge 4 is silenced by the sound wave interference by the antiphase acoustic wave emission speaker 5, propagates in the duct, and leaks to the outside. Reduce duct noise. The opening area of the open end of the duct can be increased to an arbitrary size, and the sound range can correspond to a high frequency band of 1000 Hz or more.

Third Embodiment A third embodiment will be described with reference to FIGS. FIG.
FIG. 6 is a principle view showing an operation when the acoustic door of the present invention is used as a heat exhaust port of a package that seals noise of a motor, and FIG. 6 is a side view when similarly used as an air intake and exhaust port of an engine room. is there. The same parts as those in FIG. 1 are designated by the same reference numerals.

In FIG. 5, the direct wave that has passed through the waveguide portion 1 is absorbed by the sound absorbing wall 3 having a high sound absorbing property in the front, and the secondary wave propagating by diffracting the edge 4 is the antiphase sound wave radiation. The sound is muted by the sound wave interference by the speaker 5, and external leakage of motor noise is reduced. The opening area of the heat exhaust port can be set to any size.

In FIG. 6, the direct wave that has passed through the waveguide portion 1 is absorbed by the sound absorbing wall 3 having a high sound absorbing property in the front, and the secondary wave propagating by diffracting the edge 4 is the antiphase sound wave radiation. The sound is canceled by the sound wave interference by the speaker 5. Noise that leaks from the intake and exhaust ports of the engine room to the outside is reduced. The opening area of the intake / exhaust port can be set to any size.

Fourth Embodiment A fourth embodiment will be described with reference to FIG. FIG. 7 is a cross-sectional view when the acoustic door of the present invention is used for a muffler for noise reduction used for an exhaust port of an internal combustion engine of an automobile or the like. The same parts as those in FIG. 1 are designated by the same reference numerals.
Reference numeral 7 is a sound absorbing muffler. In FIG. 7, the direct wave that has passed through the waveguide section 1 is a sound absorption muffler 7 having a high sound absorbing property in the front, and the secondary wave that is absorbed by the sound absorbing wall 3 and is propagated by diffracting the edge 4 is opposite. The sound is canceled by the sound wave interference by the phase sound wave emission speaker 5. Exhaust pressure loss due to the muffler for noise reduction can be significantly reduced.

[0023]

As described above, according to the present invention, the sound wave radiated from the noise source and passing through the waveguide 1 is converted into the direct wave and the edge 4.
Is divided into a secondary wave that is propagated after being diffracted, the direct wave is absorbed by the sound absorbing wall 3 and the sound absorbing muffler 7 in the front, and the secondary wave is the opposite phase / same sound emitted from the opposite phase sound wave emission speaker 5. The sound is silenced by the sound wave interference of the pressure sound wave.
The passage of sound waves emitted from the noise source through the opening 2 is blocked.

According to the invention, the opening 2 through which the noise passes
It is possible to increase the size of the noise to any size, and it is also possible to reduce the noise including the high frequency of 1000 Hz or more in the frequency bandwidth. The sound leakage from the soundproof room cannot be suppressed, the city noise that intrudes from the entrances and exits of offices where people come and go frequently, the noise that leaks from the opening of the air-conditioning duct, the sound intake and exhaust ports and heat exhaust ports of the soundproof package. It is possible to obtain an extremely practical acoustic door for silencing leaking noise and reducing pressure loss due to silencing of exhaust gas from an internal combustion engine such as an automobile.

Further, the space surrounded by the eaves of the building and the floor surface is made into the opening 2, so that the opening area of the waveguide 1 is infinite.
It is possible to form a door to prevent intrusion of aircraft noise, etc., and it is possible to use the acoustic door according to the present invention not only for sound waves in the air but also for sound waves in the water as in the air. Become.

[Brief description of drawings]

FIG. 1 is a diagram showing the arrangement and action of one embodiment when the present invention is used on the noise source side.

FIG. 2 is a perspective view of the first embodiment.

FIG. 3 is a diagram showing the arrangement and action of one embodiment when used on the sound receiving side as well.

FIG. 4 is a principle diagram showing an operation of the second embodiment.

FIG. 5 is a principle diagram showing an operation of the third embodiment.

FIG. 6 is a side view showing another embodiment of the same.

FIG. 7 is a cross-sectional view showing a fourth embodiment.

[Explanation of symbols]

 1 Waveguide 2 Opening 3 Sound absorbing wall 4 Edge 5 Anti-phase sound wave emission speaker 6 Sound absorbing / insulating wall 7 Sound absorbing muffler S Noise source W Secondary wavefront

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G10K 11/16 D

Claims (3)

[Claims] 1. A waveguide (1) for limiting a traveling direction of a sound wave radiated from a noise source, and an opening (2) having an opening direction different from that of the waveguide (1) are provided. A sound absorbing wall (3) that absorbs a sound wave is provided in the forward direction in which the sound wave passing through the portion (1) impinges, and an edge (where the sound wave passing through the waveguide portion (1) is diffracted into the opening (2) ( 4) An acoustic door characterized in that an anti-phase sound wave emission speaker (5) is provided in the vicinity. 2. The ratio of the length and the width of the sound wave emitting port is set to 1
The outside edge in the length direction of the sound wave emission port of the speaker, which has an elongated shape of about 0 to 1, and whose length does not exceed 1/2 wavelength of the maximum frequency of the sound wave emitted by the speaker, is the edge ( 4. The acoustic door according to claim 1, characterized in that the acoustic wave emitting port is directed in a direction in which a sound wave emitted from a noise source passes through the waveguide section (1). 3. The acoustic door according to claim 1, wherein a sound absorbing muffler (7) is used for all or part of the sound absorbing wall (3).