JP2001172925A - Active sound insulation wall and active sound insulation unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active sound insulation wall for fully reducing the sound pressure of a direct sound being radiated from a traveling sound source with a simple configuration. SOLUTION: A detection microphone 121 for detecting a noise being radiated from a sound source is installed on a straight line for connecting a sound source 10 and the upper end of a sound insulation wall 11. Also, a speaker 122 for radiating a noise cancellation sound to a sound insulation wall outer side is installed at the sound insulation wall side than the detection microphone on the straight line. An operation part 124 calculates a noise phase cancellation generation signal with the same sound pressure and opposite phase as compared with the noise being radiated from a sound source based on noise being detected by the detection microphone based on the noise being detected from the detection microphone and supplies the signal to the speaker.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active sound insulating wall and an active sound insulating unit, and more particularly to an active sound insulating wall and an active sound insulating unit having a sound insulating effect even when a sound source moves.

[0002]

2. Description of the Related Art An active microphone that detects noise radiated from a noise source by a detection microphone and outputs a sound having a phase opposite to that of the noise from the noise generation source from a speaker to reduce the noise sound pressure at the installation position of the error microphone. Noise control (ANC) is well known.

However, since a parameter related to the distance between the noise source and the detection microphone is required to generate a sound having the opposite phase to the noise, the noise radiated from the noise source moving like a noise barrier on an expressway is required. It is difficult to apply this technology when it is necessary to isolate the noise. In order to be applicable even when the noise source moves, a DSP (Digital Digital Signal) is applied to a unit group in which a plurality of units including a detection microphone, a speaker, and an error microphone are arranged.
A multi-channel active control type soundproofing device that applies a signal processing unit) and determines sound output from a speaker in consideration of movement of a noise source has already been proposed (see Japanese Patent Publication No. 7-82347). .

[0004] However, the multi-channel active control type soundproofing device has a complicated configuration, and a high processing capability is required for the DSP, so that it cannot be avoided that the device becomes expensive.
Therefore, it is desirable that a so-called single-degree-of-freedom active control type soundproofing device in which a calculation unit is provided for each unit including a detection microphone, a speaker, and an error microphone can be applied even when the noise source moves.

In view of the above, there has been already proposed a diffracted sound suppression speaker system in which an enclosure accommodating a speaker is arranged side by side at an upper end of a sound insulating wall, and a sound wave radiation opening surface of the speaker is directed in a traveling direction of a diffracted wave (Japanese Patent Laid-Open No. Hei. 9-5
4593).

[0006]

However, the diffracted sound suppression speaker system according to the above-mentioned proposal has a problem in that the direct sound emitted from the noise source is diffracted at the upper end of the sound insulating wall to suppress the diffracted sound. Since sound waves having the same phase and opposite sound pressure are emitted from the speaker, the sound pressure of the direct sound emitted from the noise source cannot be sufficiently reduced.

The present invention has been made in view of the above problems, and comprises a single-degree-of-freedom active control unit which has a simple configuration and can sufficiently reduce the sound pressure of a direct sound emitted by a moving sound source. An object is to provide an active sound insulation wall and an active sound insulation unit.

[0008]

According to the first aspect of the present invention, there is provided an active sound insulating wall which is provided in parallel with a moving direction of a sound source;
Noise detection means for detecting noise generated by a sound source arranged on a straight line connecting the movement center of the sound source and the upper end of the soundproof wall, a plurality of noise detection means arranged along the sound insulation wall, and the movement center of the sound source Noise canceling means which is disposed on the sound insulating wall side from the installation position of the noise detecting means on a straight line connecting the upper end of the sound insulating wall and the noise canceling sound on a straight line connecting the moving center of the sound source and the upper end of the sound insulating wall. A plurality of noise canceling sound generating means installed corresponding to the noise detecting means, and a noise generated by a sound source detected by the noise detecting means installed corresponding to the noise detecting means and the noise canceling sound generating means. A noise canceling sound calculating means for calculating a signal for generating a noise canceling sound from the noise canceling sound generating means is provided.

In the present invention, the noise radiated from the sound source and leaking from the upper end of the soundproof wall to the outside of the soundproof wall is directly canceled by the noise canceling sound radiated from the noise canceling sound generating means. In the active sound insulation wall according to the second invention, the noise cancellation sound calculation means generates a noise source in a line connecting the noise emitted from the noise cancellation sound generation means and the upper end of the sound insulation wall. Calculate a signal to be a canceling sound for canceling the noise.

In the present invention, the combined sound pressure of the noise and the noise canceling sound is minimized at any point within the line segment connecting the noise canceling sound generating means and the upper end of the soundproof wall. In the active sound insulation wall according to the third invention, one of the plurality of noise detection means and one of the corresponding noise canceling sound generation means are stored in the enclosure.

In the present invention, one noise detecting means and one noise canceling sound generating means are stored in the enclosure as one active noise control unit, so that interference between the noise canceling sound generating means is reduced. Is done. In the active sound insulation wall according to the fourth invention, the width of the enclosure is approximately の of the wavelength of the highest frequency of the noise to be silenced.

According to the present invention, since the width of the enclosure is set to approximately の of the wavelength of the highest frequency of the noise to be silenced, the noise can be silenced more efficiently. An active sound insulation wall according to a fifth invention is a plurality of speakers in which a plurality of noise canceling sound generation means are arranged around a straight line connecting a movement center of a sound source and an upper end of the sound insulation wall. In the present invention, since a plurality of speakers function as one large-diameter speaker, the matching range between the noise spherical wave and the noise canceling wave is widened, and the noise reduction zone is large.

[0013] The active sound insulation wall according to a sixth aspect of the present invention further includes a noise diffraction wall having an upper end inside the noise detection means on a straight line connecting the movement center of the sound source and the upper end of the sound insulation wall. In the present invention, noise radiated from the sound source is diffracted by the noise diffraction wall and detected by the noise detection means. An active sound insulation unit according to a seventh aspect of the present invention is a noise detection means attached to a soundproof wall installed in parallel to the moving direction of the sound source. A plurality of noise detecting means installed along the soundproof wall on a straight line connecting the upper ends, and noise canceling sound generating means mounted on the soundproof wall installed parallel to the moving direction of the sound source, and In order to radiate noise canceling sound on the straight line connecting the upper end of the soundproof wall, the noise detecting means is located along the soundproof wall on the soundproof wall side from the installation position of the noise detecting means on the straight line connecting the moving center of the sound source and the upper end of the soundproof wall A noise canceling sound generating means installed corresponding to a plurality of noise canceling means, and a noise canceling sound generating means installed based on the noise detecting means and the noise canceling sound generating means based on the noise generated by the sound source detected by the noise detecting means. Means To anda noise canceling sound calculating means for calculating a signal for generating a noise canceling sound.

According to the present invention, the noise canceling sound for canceling the noise detected by the noise detecting means is emitted from the noise canceling sound generating means. An active sound insulation unit according to an eighth aspect of the present invention includes: mounting means for mounting the noise canceling sound generating means to the soundproof wall;
Is further provided. According to the present invention, the noise canceling sound generating means is attached to the soundproof wall.

An active sound insulation unit according to a ninth aspect of the present invention provides a plurality of enclosures for storing one of the plurality of noise detection means and one of the corresponding noise canceling sound generation means, and the enclosure comprising a soundproof wall. Further, there is provided an attaching means for attaching to the. According to the present invention, the noise detecting means and the noise canceling sound generating means are stored in the enclosure and attached to the soundproof wall.

[0016]

FIG. 1 is a perspective view of an active sound insulation wall according to a first embodiment of the present invention. For example, it is assumed that a sound source 10 such as an automobile moves on a road in an X direction. A noise barrier 11 with a height of 8 to 10 meters along the road at the side of the road
Are installed vertically, and an active sound insulation unit 12 is installed inside the soundproof wall 11 on the road side.

FIG. 2 is a sectional view of the active sound insulation unit used in the first embodiment.
Reference numeral 2 denotes a detection microphone 121 for detecting noise radiated from the sound source 10 on a virtual axis Y connecting the sound source 10 and an upper road side edge of the soundproof wall 11, and a speaker 122 for radiating noise canceling sound in a direction opposite to the sound source 10. Is arranged. In addition,
The detection microphone 121 and the speaker 122 are housed in the enclosure 123.

In the first embodiment, the speaker is installed on the front of the enclosure. If the noise canceling sound can be radiated near the virtual axis Y connecting the sound source and the upper end of the sound insulation wall, the speaker can be mounted in the enclosure direction. Not limited to the front. For example, a speaker may be installed on the upper side of the enclosure as shown in FIG.

That is, the sound source side of the enclosure 123 is covered with the back plate 1231, and the opposite side of the sound source is opened to emit the noise canceling sound output from the speaker 122. Note that a detection microphone 121 that detects noise radiated from the sound source 10 is attached substantially at the center of the back plate 1231. The speaker 122 is attached to the baffle plate 1232 and stored in the enclosure 123.

Further, the output of the microphone 121 is guided to a calculation unit 124, and the output of the calculation unit 124 is
22. FIG. 4 is a functional diagram of the active sound insulation unit. The calculation unit 124 of the active sound insulation unit 12 basically includes a target sound pressure setting unit 1241 that generates a voltage proportional to a target sound pressure (generally, approximately zero). , Target sound pressure setting section 1241
A deviation calculating unit 1242 for calculating a deviation between a voltage proportional to the target sound pressure generated in step S1 and a voltage proportional to the noise detected by the detection microphone 121, and the soundproof wall 11 based on the deviation calculated by the deviation calculating unit 1242. And speaker 122
Control unit 1 that generates noise cancellation sound of the same phase and opposite phase to the sound pressure and phase of the noise at any point of the line segment connecting
243. The noise cancellation sound is radiated from the speaker 122. As a result, the combined sound of the noise and the noise canceling sound has a sound pressure of substantially zero at one point on the line connecting the upper end of the soundproof wall 11 and the speaker 122, and can prevent the noise from propagating outside that point.

Further, in order to more effectively mute the sound, adaptive control indicated by a broken line may be applied. That is, the monitoring microphone 1244 detects the sound pressure of the region where the sound is actually to be silenced, and the control parameter of the control unit 1243 based on the sound pressure of the region where the sound is actually desired to be silenced by the adaptive control unit 1245 and the deviation calculated by the deviation calculation unit 1242. Is calculated. The output of the control unit 1243 is fed back to the target sound pressure setting unit 1241 to adjust the target sound pressure.

FIG. 5 is a graph showing the effect of the active sound insulating wall according to the present invention. The solid line indicates the sound pressure of noise, and the broken line indicates the sound pressure after passive measures such as attaching a sound absorbing material to the sound insulating wall 11. However, according to the passive measure, the sound pressure of the high frequency component of 500 Hz or more can be reduced. However, 100-500Hz
The sound pressure of the low frequency component is not sufficiently reduced by passive measures. The sound pressure of the low-frequency component can be reduced by about 5 dB by the active measure of using the above-mentioned active sound insulation unit.

According to the active countermeasure, the compensation frequency range can be extended from 100 to 500 Hz. Further, according to the present invention, the speaker 122 is the soundproof wall 11.
Although arranged side by side along the upper end, the partition plate 12 is placed between the speakers in order to eliminate the influence of adjacent speakers.
5 (see FIG. 1).

It is desirable that the interval W between the partition plates 125 is about 1/2 of the wavelength L of the highest frequency in the frequency band of the noise to be silenced. For example, if the maximum frequency is 1 KHz, the wavelength is 340 millimeters, so the spacing between the partition plates is 170 millimeters. Further, according to the present invention, since the detection microphone and the speaker can be installed close to each other, the depth D (see FIG. 2) of the enclosure 123 can be reduced. The depth D may be 1000 millimeters (= 1 meter) or less in order to prevent the deterioration of sunshine near the sound insulation wall or the occurrence of radio interference.

Further, in order to further reduce the depth, the speaker 122 may be mounted on the baffle plate 1232 in a reverse direction. In this case, it is possible to provide a compact sound insulation wall that satisfies the restrictions on the inside (road side) and outside (non-road side) of the sound insulation wall. The noise is emitted as a spherical wave around the sound source 10, and the noise cancellation sound is emitted as a spherical wave around the speaker 122. Therefore, in the first embodiment in which one speaker 122 is arranged on the virtual axis Y connecting the sound source 10 and the upper edge road side edge of the soundproof wall 11, the noise spherical wave and the canceling spherical wave are one on the virtual axis Y. At the same time, the noise is canceled, but at a position deviated from the virtual axis Y, a difference is caused between the noise spherical wave and the canceling sound spherical wave due to a difference in curvature, and the noise canceling ability is reduced. That is, the sound reduction zone Z is limited to a narrow range around the virtual axis Y (see FIG. 2).

FIG. 6 is a cross-sectional view of an active sound insulation unit used in the second embodiment of the present invention, which aims to solve the above-mentioned problem. That is, in the active sound insulation unit 12 according to the second embodiment, the sound source 10 and the soundproof wall 11
A plurality of boxes 61i (2 ≦ i) are set around a virtual axis Y connecting the upper edge road side edges of.

The front surface of each box 61i is covered with a baffle plate 63i to which a speaker 62i is attached.
Back plate 6 with microphone 64i attached on the back
5i. The noise detected by the microphone 64i is guided to a calculation unit 66i, and the calculation unit 66i generates a noise canceling signal based on the input noise and generates a noise canceling signal.
Radiates as noise canceling sound.

In the second embodiment, the plurality of loudspeakers 62i function as one large-diameter loudspeaker having a diameter D about the virtual axis Y. Since the range that matches the noise spherical wave becomes larger than in the case of the first embodiment, the sound reduction zone Z is expanded as compared with the above-described embodiment. FIG. 6 shows two speakers 621 and 6 above and below the virtual axis Y.
Although the case where the microphone 22 and the microphones 641 and 642 are arranged is illustrated, a plurality of speakers and microphones may be arranged on a circumference of a circle centered on the virtual axis Y in a plane perpendicular to the virtual axis Y. Good. Further, the microphones may not be arranged on the circumference but may be arranged at one place.

In the above description, the plurality of calculation units 66i have the same frequency characteristics, but different control units may process different frequency bands. In the first and second embodiments, the vehicle as the sound source 10 travels substantially in the center of the road. However, when the vehicle as the sound source travels near the soundproof wall, sound is incident on the microphone. The angle becomes acute, and the active sound insulation effect may be reduced.

FIG. 7 is a perspective view of an active sound insulating wall according to a third embodiment of the present invention. The sound insulating wall 11 is a noise diffraction wall that extends obliquely upward to the inside of the sound insulating wall 11, that is, to the inside of the microphone 121 on the road side. 110 is provided. The noise diffracting section, which is the upper end of the noise diffractive wall 110, is connected to the sound source and the soundproof wall 11 when the vehicle travels substantially in the center of the road.
Is located in the vicinity of a virtual axis Y connecting the upper road side edges. That is, the microphone attached to the enclosure back plate is located between the soundproof wall 11 and the noise diffraction wall 110.

Therefore, when an automobile as a sound source travels near the soundproof wall 11, noise diffracted by the diffraction portion at the upper end of the noise diffraction wall 110 is incident on the microphone 121, and the angle of incidence on the microphone 121 is Since it is maintained almost the same as when traveling in the center of the road, it is possible to sufficiently collect noise. In FIG. 7, the diffraction wall is branched into a Y-shape from the middle of the soundproof wall.
The structure is not limited to this, as long as the noise diffracted by the noise diffracting unit located closer to the sound source than the microphone falls within the detection range of the microphone. For example, a noise diffraction wall may be installed independently inside the soundproof wall. Further, as shown in FIG. 8, a noise diffraction wall 110 having a noise diffraction portion at the upper end may be attached.

In the first to third embodiments, the soundproof wall, the speaker and the microphone stored in the enclosure, and the arithmetic unit are installed at the same time. However, the speaker and the microphone stored in the enclosure on the existing soundproof wall are used. It is also within the scope of the present invention to provide an active sound insulation wall by additionally providing an active sound insulation unit 12 including a microphone and a calculation unit.

9 and 10 are views for explaining a method of attaching the active sound insulation unit to an existing sound insulation wall. FIG. 9 shows a case where the active sound insulation unit is attached by a hook, and FIG. 10 shows a case where the active sound insulation unit is attached by welding. That is, in the case of FIG.
The hook 14 attached to the active sound insulation unit 12 is hooked on the flange of the H-shaped steel 13 connecting the
The active sound insulation unit 12 is fixed to the sound insulation wall 11 by bolting the lower end 141 of the 4 to an H-shaped steel.

In the case of FIG. 10, a steel plate 15 attached to the active sound insulation unit 12 is fixed to the bottom surface of the H-shaped steel 13 by welding or bolting. As shown in FIG. 11, an active sound insulation unit 12 is further provided on the upper end of the existing sound insulation wall 11.
The additional soundproof wall 111 to which is attached may be added by bolting or the like.

Further, as shown in FIG.
0 may be formed integrally with the additional soundproof wall 111.
It is clear that the present invention can be applied to a case where the sound source is stationary.

[0036]

According to the active sound insulation wall of the first invention,
The noise radiated from the sound source leaking from the upper end of the soundproof wall to the outside of the soundproof wall can be directly canceled by the noise canceling sound radiated from the noise canceling sound generating means. According to the active sound insulation wall of the second invention, the noise can be canceled within the line connecting the noise cancellation sound generation means and the upper end of the sound insulation wall, so that the sound insulation wall can be made compact.

According to the active sound insulation wall of the third invention, 1
Since one noise detection unit and one noise cancellation sound generation unit are stored in the enclosure as one active noise control unit, interference between the noise cancellation sound generation units is reduced, so that the noise is effectively canceled. It becomes possible. According to the active sound insulation wall of the fourth aspect, the width of the enclosure is set to approximately の of the wavelength of the highest frequency of the noise to be silenced, so that the noise can be more efficiently suppressed.

According to the active sound insulation wall of the fifth aspect, since a plurality of speakers function as one large-diameter speaker, it is possible to enlarge the sound reduction zone. According to the active sound insulation wall according to the sixth aspect of the invention, the noise is diffracted at the upper end of the noise diffraction wall and detected even when the vehicle runs close to the sound insulation wall, so that the noise can be reliably reduced. Becomes

According to the active sound insulation units of the seventh to ninth aspects, the active sound insulation wall can be easily constructed by adding the active sound insulation unit to the existing sound insulation wall.

[Brief description of the drawings]

FIG. 1 is a perspective view of an active sound insulation wall according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an active noise control unit used in the first embodiment.

FIG. 3 is a modified example of the active noise control unit used in the first embodiment.

FIG. 4 is a functional diagram of an active noise control unit.

FIG. 5 is a graph showing the effect of the active sound insulation wall according to the present invention.

FIG. 6 is a sectional view of an active noise control unit used in the second embodiment.

FIG. 7 is a perspective view of an active sound insulation wall according to a third embodiment of the present invention.

FIG. 8 is a modification example of the active sound insulation wall according to the third embodiment of the present invention.

FIG. 9 is an explanatory diagram of a method of attaching an active sound insulation unit to a soundproof wall.

FIG. 10 is an explanatory diagram of a method of attaching an active sound insulation unit to a soundproof wall.

FIG. 11 is a perspective view and a sectional view of an active sound insulation wall according to a fourth embodiment of the present invention.

FIG. 12 is a perspective view and a sectional view of an active sound insulation wall according to a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Sound source 11 ... Sound insulation wall 110 ... Noise diffraction wall 12 ... Active sound insulation unit 121 ... Detection microphone 122 ... Speaker 123 ... Enclosure 1231 ... Back plate 1232 ... Baffle plate 124 ... Calculation part

Claims (13)

[Claims] A sound-insulating wall installed parallel to a moving direction of a sound source; and a noise detecting means for detecting noise generated by the sound source arranged on a straight line connecting a moving center of the sound source and an upper end of the sound-insulating wall. A plurality of noise detecting means installed along the soundproof wall, and a noise detecting means disposed on the soundproof wall side from an installation position of the noise detecting means on a straight line connecting a movement center of the sound source and an upper end of the soundproof wall. A noise canceling sound generating means for emitting a noise canceling sound on a straight line connecting a moving center of the sound source and an upper end of the soundproof wall, wherein a plurality of noise canceling sound generating means are provided corresponding to the noise detecting means. And a noise canceling sound generator configured to correspond to the noise detecting means and the noise canceling sound generating means, and generating a noise canceling sound from the noise canceling sound generating means based on the noise generated by the sound source detected by the noise detecting means. To do And a noise canceling sound calculating means for calculating the signal of the above. 2. The noise canceling calculation means according to claim 1, wherein the noise radiated from said noise canceling sound generating means is a noise generated by said noise source within a line segment connecting said noise canceling sound generating means and an upper end of said soundproof wall. The active sound insulation wall according to claim 1, wherein a signal serving as a canceling sound for canceling the noise is calculated. 3. The active sound insulation wall according to claim 1, wherein one of said plurality of noise detection means and one of said noise canceling sound generation means corresponding thereto are stored in an enclosure. 4. The active sound insulation wall according to claim 3, wherein the width of the enclosure is approximately の of the wavelength of the highest frequency of the noise to be silenced. 5. The noise canceling sound generating means radiates the noise canceling sound to at least the soundproof wall side on a straight line connecting the movement center of the sound source and the upper end of the soundproof wall. 2. The active sound insulation wall according to claim 1. 6. The speaker according to claim 1, wherein the noise canceling sound generating means is a speaker whose back is directed to the outside of the soundproof wall on a straight line connecting the movement center of the sound source and the upper end of the soundproof wall.
The active sound insulating wall according to any one of the above items. 7. The enclosure having a depth of about 500.
The active sound insulation wall according to any one of claims 1 to 6, which is equal to or less than a millimeter. 8. The enclosure having a depth of about 250.
The active sound insulation wall according to any one of claims 1 to 6, which is equal to or less than a millimeter. 9. The active sound insulation wall according to claim 1, wherein a plurality of said noise cancellation sound generation means are arranged around a straight line connecting a movement center of said sound source and an upper end of said sound insulation wall. 10. The soundproof wall according to claim 1, further comprising a noise diffractive wall having an upper end inside the noise detecting means on a straight line connecting a movement center of the sound source and an upper end of the soundproof wall. 2. The active sound insulation wall according to claim 1. 11. A noise detecting means attached to a soundproof wall installed in parallel with a moving direction of a sound source, wherein a noise is generated between the moving center of the sound source and an upper end of the soundproof wall in order to detect noise generated by the sound source. A plurality of noise detection means installed along the soundproof wall on a straight line connecting them; and a noise canceling sound generation means mounted on the soundproof wall installed parallel to the moving direction of the sound source, wherein In order to radiate noise canceling sound on a straight line connecting the upper end of the soundproof wall, the soundproof wall is located closer to the soundproof wall than the installation position of the noise detecting means on a straight line connecting the moving center of the sound source and the upper end of the soundproof wall. A plurality of noise canceling sound generating means provided in accordance with the noise detecting means, and a plurality of noise canceling sound generating means installed in correspondence with the noise detecting means and the noise canceling sound generating means, and detected by the noise detecting means. sound Active sound insulation unit including an a noise canceling sound calculating means for calculating a signal to generate noise canceling sound from the noise canceling sound generating means based on the generated noise. 12. The apparatus according to claim 11, further comprising mounting means for mounting said noise canceling sound generating means to said soundproof wall.
4. The active sound insulation unit according to claim 1. 13. A plurality of enclosures for storing one of the plurality of noise detecting means and one of the corresponding noise canceling sound generating means, and mounting means for attaching the enclosure to the soundproof wall. The active sound insulation unit according to claim 11, further comprising: