JP3937465B2 - Diffraction sound suppression speaker system - Google Patents

Description

[0001]
[Industrial application fields]
In this invention, the sound wave propagation energy of the diffracted wave is obtained by radiating the sound wave having the opposite phase and the same sound pressure from the speaker to the sound wave diffracting the upper end of the sound insulation wall or the like and propagating to the back side, and causing the sound waves to interfere with each other. The present invention relates to a diffractive sound suppression speaker system that consumes power.
[0002]
[Prior art]
Conventionally, a speaker that radiates sound waves with the same phase and pressure as the sound waves from the noise source has been placed near the top edge of the sound insulation wall, etc., and the noise is diffracted from the sound insulation wall and the sound from the speaker to cause sound propagation. As a speaker used in a speaker system that suppresses
1. A speaker installed near the upper end of the sound insulation wall and whose speaker opening face is directed in the direction of noise.
2. A speaker installed near the top of the sound insulation wall with the speaker opening facing upward.
3. A speaker installed near the top of the sound insulation wall on the noise source side, with the speaker opening facing the top of the sound insulation wall.
Etc. are raised.
[0003]
These speakers are all designed to radiate sound waves with the same phase and pressure as the sound waves of noise, and are installed for the purpose of operating so that noise does not propagate behind the sound insulation wall. is there.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional technique, the propagation state of the wavefront of the sound wave diffracting the sound insulation wall and the propagation state of the wavefront of the sound wave emitted by the speaker installed in the vicinity of the sound insulation wall or the like do not necessarily match. Since it is often not configured, it is difficult to cope with noise having a wide frequency bandwidth, or particularly when the purpose is to mute a wide area.
[0005]
In addition, when trying to control a wide area using a plurality of speakers, adjacent speakers may affect each other, which may hinder the mute function.
[0006]
In view of the above-mentioned problems, the problem to be solved by the present invention is the propagation state of the wavefront of the sound wave at the diffraction point of the diffracted wave from the vicinity of the diffraction point with respect to the sound wave propagated by diffracting the sound insulation wall and the like, By emitting a sound wave that is as small as possible except that the difference between the wavefront propagation state of the sound wave radiated from the sound wave emission port of the diffracted sound suppression speaker has a reverse phase relationship, both sound waves are mutually connected. It is an object of the present invention to provide a practical diffractive sound suppression speaker system that emits a sound wave having a propagation characteristic with a small phase error and high interference efficiency at a point where the sound waves interfere with each other.
[0007]
[Means for Solving the Problems]
In a diffracted sound suppression speaker system that suppresses the propagation of diffracted sound by sound wave interference between a sound wave that is diffracted and propagates through a sound insulating wall and a sound wave that is output from the speaker, a plurality of speakers are connected to the outside of the long diameter of each sound wave emission port. The sound insulating wall is configured so that the edge is the upper edge of the sound insulating wall, the long diameter of the sound wave emitting port of the speaker is set to a size that does not exceed 1/2 wavelength of the maximum frequency of the sound wave emitted by the speaker, and the sound wave emission of the speaker The minor axis of the mouth is about 1/20 wavelength of the maximum frequency of the sound wave emitted by the speaker, and the sound wave radiation opening surface of the speaker is directed in the traveling direction of the diffracted wave.
[0008]
Also, a sound wave generation source such as noise is shielded by a shielding plate, and the diffraction sound suppression speaker is installed on the outer periphery of the shielding plate so that sound waves from the sound wave generation source such as noise do not reach the shadow behind the shielding plate. Create an area.
[0009]
Further, the diffusion of the speaker is restricted by installing the diffraction sound suppressing speaker on the outer periphery of the speaker enclosure.
[0010]
[Action]
In a diffracted sound suppression speaker that radiates sound waves of opposite phase and same sound pressure from a plurality of speakers arranged at the upper end of the sound insulation wall, and diffracts the upper end of the sound insulation wall and propagates the sound waves, When the same signal is applied to each speaker with the major axis of the sound wave emission port of each speaker not exceeding 1/2 wavelength of the maximum frequency of sound waves emitted by the speaker, the sound wave emission apertures of each speaker are connected. Each point in an arbitrary surface that is opposite to the surface and has a fixed distance from the surface connecting the opening surfaces has less uneven phase rotation, and is configured by connecting points of the same phase. A wavefront with a stable phase and amplitude can be obtained.
[0011]
In addition, the outer edge of the longer diameter of the sound wave emission port of the speaker is arranged to be a source of diffracted sound at the upper end of the sound insulation wall, and the short diameter of the sound wave emission port of the speaker is set to about 1 of the maximum frequency of the sound wave emitted by the speaker. When the size is about 20 wavelengths, the edge that is the source wave source of the diffracted sound and the short diameter of the sound wave emission port that is the source of the sound wave of the diffracted sound suppression speaker corresponding to the source wave source of the diffracted sound Since the difference in position with respect to the center line can be suppressed within an allowable range in sound wave interference, the phase error of sound wave interference between the diffracted sound and the speaker sound can be reduced.
[0012]
When the direction of the sound wave radiating aperture of the speaker installed at the upper end of the sound insulation wall is directed toward the traveling direction of the diffracted wave, the direction of the sound wave radiating opening surface of the speaker and the progress of the straight wave traveling straight in the vicinity of the upper end of the sound insulating wall Assuming that the angle formed by the direction is θ, the range controlled by the diffracted sound suppression speaker increases toward the straight wave side as θ decreases, and is controlled by the diffracted sound suppression speaker as θ increases. The range is tilted toward the diffracted sound, and the controlled range is narrowed.
[0013]
When the diffracted sound suppression speaker configured as described above is installed on the outer periphery of the shielding plate and the sound wave generation source is shielded by the shielding plate, the sound wave from the sound wave generation source is difficult to reach behind the shadow by the shielding plate. Can be made.
[0014]
Similarly, when the above-described diffraction sound suppressing speaker is installed on the outer periphery of the speaker enclosure, a directional speaker can be obtained.
[0015]
【Example】
Example 1
A diffractive sound suppression speaker according to the present invention will be described with reference to FIGS. 1, 2A and 2B. 1 is a perspective view showing a first embodiment in which a plurality of diffracted sound suppression speakers according to the present invention are arranged on the upper end of a semi-infinite sound insulation wall, and FIG. 2A is a wavefront of the plurality of diffracted sound suppression speakers in FIG. FIG. 2B is an elevation view showing the propagation state of the diffracted wave.
11, 12, 13,... Are first, second, third,... Diffraction sound suppression speakers, 2 is a semi-infinite sound insulation wall, 31, 32, 33,. 2, 3,... The outer edge of the long diameter of the sound wave emission port, 4 is the short of the sound wave emission ports of the first, second, third,. A center line connecting the centers of the diameters, 5 is an in-phase wavefront, S is a noise source, and θ is an angle formed by the direction of the sound wave radiating aperture and the traveling direction of the straight wave. The operation will be described below.
[0016]
The two diffracted sound suppression speakers adjacent to each other among the plurality of diffracted sound suppression speakers 11, 12, 13,... Arranged on the upper end of the semi-infinite sound insulating wall 2 are the second and third diffracted sound suppression speakers. As the speakers 12 and 13, the influence given to each diffracted sound suppression speaker by another diffracted sound suppression speaker when the same signal is applied thereto will be described with reference to FIG.
The maximum frequency of the sound wave radiated from the second and third diffracted sound suppression speakers 12 and 13 is defined as f ₀ , and the major diameter of the sound wave emission port of the second and third diffracted sound suppression speakers 12 and 13 is determined. The surface of the second and third diffracted sound suppression speakers 12 and 13 is opposed to the surface connecting the sound wave radiating apertures by making the size not to exceed a half wavelength of the maximum frequency f ₀ of the emitted sound wave. As a result, a stable in-phase wavefront 5 is obtained in which the phase rotation is not significantly disturbed by interference with sound waves emitted from other adjacent diffracted sound suppression speakers.
[0017]
Second, and, if the maximum frequency of the sound waves radiated from the third diffracted sound suppression speakers 12 and 13 of the smaller frequency than f _0, because the wavelength is larger than the wavelength of the maximum frequency f _0, the two within any wavefront surface opposite that had been wave emission opening of the diffracted sound suppression speaker, than when the maximum frequency f ₀ of the acoustic wave, the influence of the wave front of the other diffracted sound suppression speaker adjacent each receives to become Nikuku-phase wavefront 5 is obtained more stable.
[0018]
Next, an arbitrary one of the plurality of diffracted sound suppression speakers 11, 12, 13,... Arranged at the upper end of the semi-infinite sound insulating wall 2 is taken out, the second diffracted sound suppression speaker 12 is taken out, and the second FIG. 2 (B) shows an elevational operation of the diffracted wave diffracting the long-diameter outer edge 32 of the sound wave emission port of the diffraction sound suppression speaker 12 and the sound wave emitted from the sound wave emission port of the second diffraction sound suppression speaker 12. ).
The sound wave propagating straight from the far rear side of the second diffracted sound suppression speaker 12 diffracts at the long-diameter outer edge 32 of the sound wave emission port of the second diffracted sound suppression speaker 12 and radiates toward the back side which is shaded by the semi-infinite sound insulation wall 2 To spread. At this time, the diffracted sound propagates along the major-diameter outer edge 32 of the sound wave emission port of the second diffracted sound suppression speaker 12 as a source wave generation source of the diffracted sound. In order to efficiently suppress the diffracted sound by causing the diffracted sound to interfere with the sound wave by the antiphase sound wave, the phase difference between the diffracted sound and the antiphase sound wave should be within ± 10 °.
Therefore, the short diameter of the sound wave emission port of the second diffracted sound suppression speaker 12 is set to a magnitude of about 1/20 wavelength of the maximum frequency f ₀ of the sound wave radiated by the second diffractive sound suppression speaker 12. The long-diameter outer edge 32 of the sound wave emission port of the second diffracted sound suppression speaker 12 serving as the sound source wave generation source, and the short-diameter center line of the sound wave emission port serving as the sound wave generation source of the second diffraction sound suppression speaker 12 Thus, it is possible to reduce errors caused by the difference from the position 4 and to reduce speaker output loss caused by making the speaker opening area smaller than necessary.
[0019]
When the direction of the sound wave radiation opening surface of the second diffracted sound suppression speaker 12 is set to face the traveling direction of the diffracted wave, the direction of the sound wave radiation opening surface of the second diffraction sound suppression speaker 12 and the vicinity of the upper end of the sound insulation wall go straight. When the angle formed by the traveling direction of the straight traveling wave is θ, the range controlled by the second diffracted sound suppression speaker 12 increases toward the straight traveling wave side as θ decreases, and as θ increases, The range controlled by the second diffracted sound suppression speaker 12 is inclined toward the diffracted sound side, and the controlled range becomes narrow.
[0020]
Example 2
A second embodiment will be described with reference to FIG. Portions common to FIGS. 1 and 2 are denoted by the same reference numerals.
6 is a shielding plate.
FIG. 3 shows a second embodiment of the present invention, in which a plurality of first, second, third,... Diffracted sound suppression speakers 11, 12, 13,. The sound wave from the noise source S, which is installed on the outer periphery and diffused radially, creates an area where it is difficult for the shielding plate 6 to go behind the shadow.
[0021]
Example 3
A third embodiment will be described with reference to FIG. 1 to 3 are denoted by the same reference numerals.
7 is an alarm sound source, and 8 is an emergency vehicle.
FIG. 4 shows a third embodiment according to the present invention, in which a plurality of first, second, third,... Diffracted sound suppression speakers 11, 12, 13,. Installed on the outer circumference so that the angle θ between the traveling direction of the sound wave at the boundary between the straight wave and the diffracted wave and the direction of the sound wave radiation opening surface of the diffracted sound suppression speaker has an appropriate size. Thus, the sound wave from the alarm sound source 7 that is diffused radially is prevented from entering the interior of the emergency automobile 8 that is shaded by the shielding plate 6 with an excessive volume and is diffused over a wide range outside the vehicle. The volume of the alarm sound is not reduced.
[0022]
Example 4
Example 4 will be described with reference to FIG. Parts common to FIGS. 1 to 4 are given the same reference numerals.
Reference numeral 9 is a speaker, and 10 is a speaker enclosure.
FIG. 5 shows a fourth embodiment according to the present invention, in which a plurality of first, second, third,..., Diffraction sound suppression speakers 11, 12, 13,. Installed on the left and right sides in such a way that the angle θ formed by the traveling direction of the sound wave at the boundary between the straight wave and the diffracted wave and the direction of the sound wave radiation opening surface of the diffracted sound suppression speaker has an appropriate size. The sound wave from the speaker 9 diffracts the energy of the diffracted wave propagated by diffracting the left and right side edges 31, 32, 33,. By restricting the diffusion, directivity is given to the speaker.
[0023]
【The invention's effect】
According to the present invention, the sound source is shaded by the sound insulation wall to create an area where the sound wave radiated from the sound source is diffracted and propagated, and the propagation state of the wave front of the diffracted wave is radial with the top edge of the sound insulation wall as the source wave source. The sound wave is controlled so that the wave front has a uniform characteristic, and the diffracted wave is diffused radially from the diffracted sound suppression speaker near the diffraction point. The propagation energy of the diffracted wave can be efficiently reduced by emitting two sound waves and causing the two sound waves to interfere with each other.
[0024]
Accordingly, the diffracted sound suppression speaker system according to the present invention can effectively reduce the sound wave diffracted to the back side of the sound insulating wall by appropriately setting the sound insulating wall. It can be used for reducing noise propagated to an area shaded by a plate, suppressing alarm sound of an emergency vehicle from entering the passenger compartment, or a speaker having directivity.
Needless to say, the diffracted sound suppression speaker system according to the present invention can handle not only the sound waves in the air but also the sound waves in the water as in the air.
[Brief description of the drawings]
FIG. 1 is a perspective view showing Example 1. FIG.
FIG. 2A is a plan view showing an in-phase wavefront.
(B) Elevated view showing the propagation state of the diffracted wave.
3 is a perspective view showing Example 2. FIG.
4 is a perspective view showing Example 3. FIG.
5 is a perspective view showing Example 4. FIG.
[Explanation of symbols]
11, 12, 13, ... 1st, 2nd, 3rd, ... Diffraction sound suppression speaker 2 Semi-infinite sound insulation walls 31, 32, 33, ... 1st, 2nd, 3rd, ... Long-diameter outer edge 4 of the sound wave emission port 4 Center line of the short diameter of the sound wave emission port 5 In-phase wave surface 6 Shield plate 7 Alarm sound source 8 Emergency car 9 Speaker 10 Speaker enclosure S Sound source θ Direction of sound wave radiation opening surface and traveling direction of straight wave The angle between

Claims (1)

  In the diffracted sound suppression speaker system that suppresses the propagation of diffracted sound by sound wave interference between the sound wave that is diffracted and propagates through the sound insulating wall and the sound wave that is output from the speaker, A slit-like speaker sound wave emission port of the speaker unit, a sound wave emission edge whose longitudinal outer edge of the sound wave emission port is a side edge opposite to the noise source, and an opening surface of the sound wave emission port as a noise source An array of speaker units is constituted by a sound wave emitting surface facing the direction of propagation of noise diffracted to the opposite side, and the major axis of the sound wave emitting port of one speaker unit is set to 1 of the maximum frequency of the sound wave emitted by the speaker. / 20 wavelength that does not exceed 2 wavelengths, and the short diameter of the sound wave emission port is 1/20 wavelength of the maximum frequency of the sound wave emitted by the speaker As the magnitude of the degree, the sound wave emission edge having a predetermined length is regarded as a point where the diffracted sound caused by noise is viewed macroscopically, that is, one element wave generation source of diffraction noise, and the one element wave generation A sound wave that is provided in the vicinity of the source and emits a sound wave having homogeneity in phase characteristics and amplitude characteristics. Diffracting sound suppression speaker system, wherein both of the macroscopic elemental wave and the elemental wave are caused to wave interfere to dissipate the diffracted sound propagation energy.

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