JP2009145740A - Sound absorber, sound absorber group and acoustic room - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To excellently absorb sound without using an electric driving means. <P>SOLUTION: A sound absorbing mechanism of a resonance system is provided by a resonance system by a vibration section 30 and an air layer 40, in a sound absorber 1, and sound is absorbed with a resonance frequency as a peak frequency. A phase of a sound wave of the resonance frequency which comes through an internal space 23, is shifted by a half wavelength from vibration of the resonance system. Thereby, when air is pressed out to a through-hole 13 from the air layer 40 by vibration of the vibration system, the air in the air layer 40 moves into a duct 20 and vibration of the vibration section 30 becomes large. When the vibration section 30 is displaced to an opposite side of the air layer 40 by the vibration of the vibration system, the air in the duct 20 moves to the air layer 40 and vibration of the vibration section 30 becomes large. Thus, the vibration of the vibration section 30 becomes large in the sound absorber 1, and energy of the sound wave is greatly consumed and sound is further absorbed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for absorbing sound.

  As a sound absorber that actively absorbs sound, for example, there is a sound absorber disclosed in Patent Document 1. The sound absorber disclosed in Patent Document 1 has a porous material on the surface and a back wall on the back side, and an air layer is provided between the porous material and the back wall. In the air layer, a sound pressure detector for detecting the sound pressure in the air layer and a controller for driving the rear wall are arranged. In this sound absorber, when a sound wave reaches the surface, the sound pressure detector outputs a signal indicating the sound pressure in the air layer. When this signal is input to the controller, the controller processes the input signal to drive the back wall. Then, the back wall vibrates, and the sound pressure radiated by the vibration cancels the sound wave that has reached the sound absorbing body, so that the sound is absorbed.

Japanese Patent Laid-Open No. 10-63271

  Now, in the sound absorber disclosed in Patent Document 1, by outputting from the back wall a sound whose phase is reversed with respect to the incident sound wave, the sound wave is efficiently canceled and the sound is absorbed. However, the sound absorber disclosed in Patent Document 1 requires an electrically driven device such as a sound pressure detector or a controller in order to output a sound whose phase is inverted, and supplies power. There is a problem that sound absorption cannot be performed in places where it is difficult to perform sound absorption.

  The present invention has been made under the above-described background, and an object of the present invention is to provide a technique for efficiently absorbing sound without using an electric driving means.

  In order to solve the above-described problems, the present invention provides a solid body having a plate-like or membrane-like vibrating portion that is deformed by an external force and an air layer inside, and a through-hole penetrating from the outer surface of the solid body to the air layer And a solid body having the vibrating portion as a part of a surface forming the solid body, and a communication pipe having an internal space communicating with the through hole, and the length of the internal space of the communication pipe is: There is provided a sound absorber that is different from a wavelength of a resonance frequency of a resonance system constituted by the vibrating section and the air layer by a half wavelength.

In the present invention, the interior of the solid body has a tubular passage connected to the air layer, and the communication pipe penetrates the vibration part and communicates with the passage, and from one end of the communication pipe to one end of the passage. May be different by a half wavelength from the wavelength of the resonance frequency of the resonance system constituted by the vibrating part and the air layer.
In the present invention, an extendable and contractible elastic member may be interposed between the communication pipe and the vibration part, and the communication pipe and the vibration part may be fixed to the elastic member.
Moreover, in this invention, the said through-hole part of the said vibration part may be dented inside the said solid, or may protrude outside the said solid.

  In addition, the present invention provides a sound absorber group in which a plurality of the sound absorbers are connected, and the resonance frequency of each sound absorber is different for each sound absorber.

The present invention also provides an acoustic chamber having the sound absorber.
The present invention also provides an acoustic room having the sound absorber group.

  According to the present invention, it is possible to efficiently absorb sound without using an electric drive means.

  1 is an external view of a sound absorber 1 according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the sound absorber 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. As shown in the figure, the sound absorber 1 is roughly composed of a main body part 10, a duct part 20, and a vibration part 30.

  The main body 10 is formed of a metal-made rectangular bottom surface 11 serving as a bottom surface of the sound absorber 1 and a metal side wall portion 12 serving as a side wall of the sound absorber 1. A through hole 13 that penetrates the bottom surface portion 11 is provided in the central portion of the bottom surface portion 11. Further, the side wall portion 12 has a rectangular tube shape, and an end portion on one opening side is fixed to the bottom surface portion 11.

  The vibration unit 30 is a rectangular member in which a polymer compound is formed in a film shape. The vibration unit 30 is fixed in a state where tension is applied to an end portion on the side opposite to the end portion of the side wall portion 12 fixed to the bottom surface portion 11 side. Thereby, the air layer 40 is formed in the sound absorber 1 by the main body 10 and the vibration part 30. In the present embodiment, the vibrating portion 30 is formed by forming a polymer compound into a film shape. However, if the vibrating portion 30 vibrates when a sound wave arrives in a state of being fixed to the side wall portion 12, a metal portion may be used. A material or a wood material may be formed into a plate shape.

  The duct part 20 is formed in the shape which bent the metal square tube, has the through-hole 21 and the opening end 22, and has the interior space 23 inside. The duct portion 20 is fixed to the bottom surface portion 11 and the side wall portion 12, the through hole 21 is connected to the through hole 13 of the bottom surface portion 11, and the opening end 22 is located next to the vibration portion 30 and faces the sound incident direction. Yes. By fixing the duct part 20 in this way, the outside of the sound absorber 1 and the air layer 40 are connected via the internal space 23. In addition, the raw material of the member which forms the main-body part 10 and the duct part 20 is not limited to a metal, Other materials, such as a synthetic resin and a timber, may be sufficient.

  Next, the operation of the sound absorber 1 will be described. In the sound absorber 1, the air layer 40 is behind the vibration unit 30 on which sound waves are incident, and the vibration unit 30 and the air layer 40 constitute a resonance system. The resonance frequency of the resonance system is determined by the material physical properties (Young's modulus, density), thickness, area, tension, and thickness of the air layer 40 of the vibration unit 30. In the present embodiment, the length of the internal space 23 of the duct portion 20 (the length of the central axis of the internal space 23) is the wavelength of the resonance frequency of the resonance system constituted by the vibration portion 30 and the air layer 40. It is formed in half length.

  First, in the sound absorber 1, a resonance sound absorbing mechanism is realized by a resonance system including the vibration unit 30 and the air layer 40, and the incident sound is absorbed with the sound absorption coefficient at the resonance frequency of the resonance system as a peak. . When the sound wave reaches the sound absorber 1, the reached sound wave enters the duct part 20 from the opening end 22 of the duct part 20 adjacent to the vibration part 30, passes through the internal space 23, and enters the through hole 13 of the bottom surface part 11. To reach. Here, the resonance system by the vibration part 30 and the air layer 40 vibrates at the resonance frequency, but the length of the duct part 20 is formed to be half the wavelength of the resonance frequency. Among the sound waves that reach the through-hole 13 through the space 23, the sound wave of the resonance frequency is out of phase with the vibration of the resonance system by a half wavelength.

Then, when the vibration unit 30 is displaced toward the air layer 40 due to the vibration of the resonance system and the air is pushed out from the air layer 40 to the through hole 13, the through hole 13 passes through the internal space 23. Since the sound wave having the resonance frequency is shifted in phase by half a wavelength from the vibration of the resonance system, the sound pressure is low, and more air in the air layer 40 moves into the duct 20 and the vibration unit 30. The vibration of is increased.
Further, when the vibration unit 30 is displaced to the side opposite to the air layer 40 due to the vibration of the resonance system and the air in the duct 20 is sucked out to the air layer 40, the internal space is formed in the through hole 13. Since the sound wave of the resonance frequency that has passed through 23 is out of phase by half a wavelength with the vibration of the resonance system, the sound pressure is high, and more air in the duct 20 moves to the air layer 40 and vibrates. The vibration of the part 30 increases.

  According to the present embodiment, the vibration of the vibration part 30 is increased, and the energy of the sound wave is greatly consumed, so that the sound is efficiently absorbed as compared with the case where the duct part 20 is not provided. If this sound absorber is arranged in the sound field, it is possible to absorb sound of a specific frequency and control the acoustic characteristics of the sound field.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows.

  The sound absorber according to the present invention is not limited to the shape shown in FIGS. For example, as illustrated in FIG. 4, the sound absorber may have a rectangular parallelepiped shape in which the duct portion is not exposed to the outside. FIG. 5 is an exploded perspective view of the sound absorber 2 shown in FIG. The sound absorber 2 is roughly composed of a vibration part 100, a side wall part 110, a pipe 120, a partition plate 130, and a duct part 140.

  The vibration unit 100 is a rectangular member in which a polymer compound is formed in a film shape, and a through hole 101 is provided in the center portion. The side wall part 110 is made of metal and has the shape of a square tube like the side wall part 12. The tube 120 is a metal square tube and has an open end 121 and an open end 122. The partition plate 130 is a rectangular member made of metal, and a through hole 131 and a through hole 132 are provided in the central portion. The duct portion 140 is made of metal and has a shape in which one opening of the square tube is closed. Moreover, the duct part 140 has the partition wall 141 inside. The partition wall 141 is fixed to the bottom surface of the duct part 140, and forms a bent passage inside the duct part 140.

  In the sound absorber 2, the end portion on one opening side of the side wall portion 110 is fixed to the partition plate 130, and the vibrating portion 100 is fixed to the other opening portion in a tensioned state. In addition, one end of the tube 120 is fixed to the through hole 101 and the other end is fixed to the peripheral edge of the through hole 131. Further, the peripheral edge portion of the partition plate 130 is fixed to the end portion of the duct portion 140 that is open. When the members are combined in this way, an air layer is formed between the vibration unit 100 and the partition plate 130 inside the sound absorber 2. Further, when the members are combined, an internal space is formed in the sound absorbing body 2, which is connected to the through hole 101 → the pipe 120 → the passage in the duct part 140 → the through hole 132.

  In the sound absorber 2, since there is an air layer behind the vibration part 100 on which sound waves are incident, the vibration part 100 and the air layer constitute a resonance system. In the present embodiment, the length of the internal space (the length of the central axis of the internal space) is formed to be half the wavelength of the resonance system resonance frequency.

  First, in the sound absorber 2, a resonance sound absorption mechanism is realized by a resonance system formed by the vibration unit 100 and the air layer behind the vibration unit, and the incident sound is obtained with the sound absorption coefficient at the resonance frequency of the resonance system as a peak. Sound is absorbed. When the sound wave reaches the sound absorber 2, the reached sound wave reaches the through hole 132 through the path of the through hole 101 → the pipe 120 → the passage in the duct part 140 → the through hole 132. Here, the resonance system by the vibration part 100 and the air layer behind the vibration part vibrates at the resonance frequency, but the length of the internal space from the through hole 101 to the through hole 132 is half the wavelength of the resonance frequency. Therefore, among the sound waves that have reached the through-hole 132 through the internal space, the sound wave of the resonance frequency is out of phase with the vibration of the resonance system by a half wavelength.

Then, when the vibration unit 100 is displaced toward the partition plate 130 due to the vibration of the resonance system and the air in the back air layer is pushed out to the through hole 132, the through hole 132 passes through the internal space. Since the sound wave of the resonance frequency is out of phase with the vibration of the resonance system by a half wavelength, the sound pressure is low, and more air in the air layer moves into the internal space and the vibration of the vibration unit 100 growing.
In addition, when the vibration unit 100 is displaced to the side opposite to the back air layer of the vibration unit 100 due to the vibration of the resonance system and the air in the internal space is sucked into the back air layer, The sound pressure of the sound wave of the resonance frequency that passed through the internal space is high because the phase and the vibration of the resonance system are shifted by a half wavelength, and more air in the internal space moves to the back air layer. Thus, the vibration of the vibration unit 100 increases.

As described above, also in the present embodiment, the vibration of the vibration unit 100 is increased and the energy of the sound wave is consumed, so that the sound is absorbed more efficiently than when the internal space is not provided.
In the modification described above, the peripheral edge of the opening of the tube 120 is fixed to the vibrating part 100. However, as shown in FIG. 6, the damper is formed of a material having elasticity and internal loss in the form of a film. The member 150 may be interposed between the tube 120 and the vibration unit 100.
In addition, as shown in FIG. 7, a sliding bearing 151 may be interposed between the vibrating part 100 and the pipe 120. According to this configuration, when the vibration unit 100 vibrates while the back air layer is sealed, the sliding support 151 expands and contracts in the direction of the arrow in the drawing, so that the vibration unit 100 is fixed to the pipe 120. The vibration of the vibration unit 100 is not hindered.
Further, in the above-described modification, the through hole 101 and the pipe 120 may be in other portions such as a position close to the side surface instead of the central portion of the sound absorber 2.

  In the above-described modification, the height of the tube 120 is the same as the height of the side wall portion 110, but the height of the tube 120 is set lower than the height of the side wall portion 110 as shown in FIG. Also good. On the other hand, the height of the tube 120 may be higher than the height of the side wall portion 110, and the number of passages in the duct portion may not be one but may be plural.

In the present invention, the cross-sectional shape of the internal space 23 communicating with the air layer behind the vibration unit 20 is not limited to a rectangle, and may be another shape such as a circle or an ellipse.
Further, as shown in FIG. 9, sound absorbers having different peak frequencies of sound to be absorbed may be connected so that sounds having a plurality of frequencies can be absorbed.
In addition, the sound absorber and the sound absorber group in which the sound absorbers are connected in the present embodiment can be arranged in various acoustic chambers that control acoustic characteristics. Here, the various acoustic rooms include soundproof rooms, halls, theaters, listening rooms for audio equipment, living rooms such as conference rooms, spaces for various transportation equipment such as vehicles, and housings for speakers and musical instruments.

1 is an external view of a sound absorber 1 according to an embodiment of the present invention. 1 is an exploded perspective view of a sound absorber 1. FIG. It is the sectional view on the AA line of FIG. It is an external view of the sound absorber 2 which concerns on the modification of this invention. 3 is an exploded perspective view of the sound absorber 2. FIG. It is an external view of the sound absorber 2 which concerns on the modification of this invention. It is sectional drawing of the opening end 121 vicinity of the sound absorber 2 which concerns on the modification of this invention. It is an external view of the sound absorber 2 which concerns on the modification of this invention. It is an external view when two or more sound-absorbing bodies 2 are connected.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Sound absorption body, 10 ... Main-body part, 11 ... Bottom face part, 12 ... Side wall part, 13 ... Through-hole, 20 ... Duct part, 21 ... Through-hole 22 ... Open end, 23 ... Internal space, 30 ... Vibrating part, 40 ... Air layer, 100 ... Vibrating part, 101 ... Through hole, 110 ... Side wall part, 120 ... pipe, 121, 122 ... open end, 130 ... partition plate, 131, 132 ... through hole, 140 ... duct part, 141 ... partition wall, 150 ... damper Element.

Claims (7)

A plate-like or membrane-like vibrating part that is deformed by an external force;
A solid body having an air layer therein, a solid body having a through-hole penetrating from the outer surface of the solid body to the air layer, and the vibrating portion as a part of a surface forming the solid body;
A communication pipe having an internal space communicating with the through hole;
Have
The length of the internal space of the communication pipe is different from the wavelength of the resonance frequency of the resonance system composed of the vibrating part and the air layer by a half wavelength. Inside the three-dimensional body, there is a tubular passage that leads to the air layer,
The communication pipe passes through the vibrating portion and communicates with the passage.
2. The length from one end of the communication pipe to one end of the passage is different from the wavelength of the resonance frequency of the resonance system constituted by the vibration part and the air layer by a half wavelength. Sound absorber.   The sound absorber according to claim 2, wherein a telescopic elastic member is interposed between the communication pipe and the vibration part, and the communication pipe and the vibration part are fixed to the elastic member.   4. The sound absorber according to claim 2, wherein the through-hole portion of the vibration part is recessed inside the solid or protrudes outside the solid.   5. A sound absorber group in which a plurality of sound absorbers according to claim 1 are connected, wherein the resonance frequency of each sound absorber is different for each sound absorber.   An acoustic chamber having the sound absorber according to any one of claims 1 to 4.   An acoustic chamber having the sound absorber group according to claim 5.

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