JPH07302087A - Sound absorbing structure body - Google Patents

Abstract

PURPOSE:To provide a sound absorbing structural body which is compact and is capable of easily increasing the sound absorbing power of a low compass. CONSTITUTION:This sound absorbing structural body 16 is integrally composed by arraying plural pieces of pipes 18 varying in length transversely in one row and connecting these pipes to each other or fastening the pipes to each other by means of the separate members to be exclusively used. The respective pipes 18 are closed at one-side ends to constitute closed parts 20 and are opened at the other-side ends to constitute apertures 22. The height positions of the apertures 22 are aligned to one row with all the pipes 18-1 to 18-n.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing structure for absorbing sound in a room such as a hall or a listening room,
The sound absorption in the low frequency range around 100 Hz can be realized compactly.

[0002]

2. Description of the Related Art A conventional sound absorbing structure in a room such as a hall or a listening room is shown in FIG.
In general, a plate-shaped member, a member 14 made of a porous material, a material having a hole, or the like is arranged via a back air layer 12.

[0003]

According to the conventional sound absorbing structure, the sound absorbing frequency characteristic changes depending on the thickness W of the back air layer 12, and it is necessary to increase the value of W as the sound absorbing power in the low sound range is increased. was there. Therefore, for example, 100Hz
In order to obtain a large sound absorption force with a normal incidence sound absorption coefficient of 80% or more in the front and rear, W = 200 mm or more is required, and there is a problem that the room becomes narrow. In addition, when the thickness is W = 200 mm or more, general interior panel dimensions (width × height 910 × 1820,
The thickness could not be reduced to about 70 mm).

The present invention intends to solve the above problems in the prior art and to provide a sound absorbing structure which is compact and can easily enhance the sound absorbing power in the low frequency range.

[0005]

The invention according to claim 1 is
It has a structure in which a plurality of cavities having different lengths, one of which is closed and the other of which is opened, are arranged such that the openings on the open side are adjacent to each other. According to a second aspect of the present invention, the opening portion of the cavity or a position in the vicinity thereof is closed with a flow resistance material having air permeability. According to a third aspect of the present invention, the plurality of cavities are formed along a wall surface or a ceiling surface of the chamber. According to a fourth aspect of the present invention, the plurality of cavities are formed in a panel body. According to a fifth aspect of the present invention, each of the plurality of cavities is formed by a pipe.

[0006]

According to the invention as set forth in claim 1, the sound wave incident into the cavity through each opening forms a standing wave with a specific frequency component according to the length of the cavity, and the interior of the cavity is repetitively oscillated. Energy is consumed by friction on the wall surface and viscous action between air particles at the opening. In addition, the sound wave reflected by the closed part of the cavity and emitted again from the opening to the outside is diffracted at the opening, and a part of the energy flows into the adjacent cavities, and energy is exchanged between the cavities. Be done. For this reason, coupled vibration occurs in the two cavities for a specific frequency component depending on the combination of the lengths of adjacent cavities, and due to friction on the inner wall surfaces of the cavities and viscous action between air particles at the openings. It consumes energy.

Therefore, according to the first aspect of the invention, sound is absorbed by the resonance of each cavity alone and the coupled vibration in the plurality of cavities. Since the specific frequency can be intensively absorbed by the length of the cavity, the sound absorption frequency characteristic can be easily set to a desired state. Also,
Since the sound absorption frequency can be set according to the length of the cavity, it is possible to make the thickness thin and relatively compact even when absorbing sound in the low frequency range, and it is also possible to form a general interior panel.

According to the second aspect of the present invention, since the flow-resisting material such as glass wool, cloth, gauze or the like is used to close the opening of the cavity having a high air particle velocity or its vicinity, sound absorption is added here. It is possible to increase the sound absorption. According to the third aspect of the present invention, the plurality of cavities are configured along the wall surface of the chamber or the cavities, whereby the space can be efficiently arranged. According to the invention described in claim 4, by constructing the plurality of cavities in the panel body, it is possible to configure a sound absorbing panel having an outer shape equivalent to that of a general interior panel, which facilitates construction. Moreover,
Since the sound absorption frequency characteristic can be set by the length of the cavity,
The panel body can be made thin even when absorbing sound in the low frequency range. According to the invention described in claim 5, the plurality of cavities can be easily configured by configuring the plurality of cavities with pipes, respectively.

[0009]

FIG. 1 shows an embodiment of the present invention. The sound absorbing structure 16 is configured to mainly absorb sound in a low sound range of about 60 to 160 Hz. Sound absorbing structure 16
Is a plurality of pipes 18 (18-1 to 1) having different lengths.
8-n) are arranged side by side in a row and connected to each other, or separately attached to each other by a dedicated member to be integrally formed. Each pipe 18 has a predetermined wall thickness (about 2 mm in this embodiment) and a predetermined inner diameter (diameter 60 mm in this embodiment).
It is composed of a linear rigid pipe made of synthetic resin or the like having a circular cross section. One end of each pipe 18 is closed to form a closing part 20, and the other end is opened to form an opening 22. The height positions of the openings 22 are arranged in a line in all the pipes 18-1 to 18-n. Therefore, the openings 22 are arranged adjacent to each other.

The cavity 24 (24-1 to 24-n) formed in each pipe 18-1 to 18-n has a length L.
Is 1 / the center frequency of the sound wave absorbed by the cavity
4 wavelengths. Here, the cavity length L (= pipe length) is 1.35 m, 1.06 m, 0.85 m,
Five kinds of pipes of 0.68m and 0.53m are used, and these are 63Hz, 80Hz and 100H, respectively.
Sound is absorbed mainly at z, 125 Hz, and 160 Hz (that is, 1/3 octave band pitch) (sound velocity = 340 m).

The neck portion (opening 22 or its vicinity) of the cavity 24 of each pipe 18 is made of glass wool, cloth,
It is closed with a flow resistant material (material having flow resistance) 26 having gas permeability such as gauze.

The sound absorbing principle of the sound absorbing structure 16 of FIG. 1 will be described. FIG. 3 shows two adjacent pipes 18-j, 18-k of the sound absorbing structure 16 of FIG. Cavities 24-j, 2 of each pipe 18-j, 18-k
Let 8-k lengths be L1 and L2. The sound waves in the room enter the cavities 24-j, 24-k through the openings 22-j, 22-k, are reflected by the closing portions 20-j, 20-k at the other end, and are opened 22-j. It is again released into the room from j, 22-k. At this time, wavelengths λ1 and λ2 (L1 = λ1 / 4, L2 = λ2 / 4) corresponding to four times the lengths L1 and L2 of the cavities.
Sound waves of standing waves S1 and S2 are generated, and friction and opening 2 on the inner wall surfaces of the cavities 24-j and 24-k are generated while repeating the vibration.
Energy is consumed by viscous action between air particles at 2-j and 22-k, and sound absorption is performed around these wavelengths λ1 and λ2. For example, L1 = 1.35 m, L2 = 0.5
If 3 m, λ1 = 5.4 m, λ2 = 2.12 m, and the frequencies f1 and f of the center of the sound wave absorbed by each
2 is f1 = 63 Hz and f2 = 160 Hz.

On the other hand, the sound waves reflected by the closing portions 20-j and 20-k and emitted from the opening portions 22-j and 22-k are diffracted by the opening portions 22-j and 22-k to generate energy. Radiate. Part of the energy is the openings 22-k, 22- of the other pipes 18-k, 18-j adjacent to each other.
The light enters from the j into the cavities 24-k and 24-j. In this way, coupled vibration is generated between the adjacent pipes 18-j and 18-k, and energy is transferred. During this coupled vibration, energy is consumed and sound is absorbed due to friction on the inner wall surfaces of the cavities 24-j and 24-k and viscous action between air particles at the openings 22-j and 22-k. Be done.
This coupled vibration can be grasped as a double-ended closed tube mode in which the pipes 18-j and 18-k are regarded as a series of pipes, and sound absorption is performed around a wavelength λ3 determined as L1 + L2 = λ3 / 2. For example, the above L1 = 1.35 m,
When L2 = 0.53 m, λ3 = 3.76 m, and the frequency f3 at the center of the sound wave absorbed by the coupled vibration is f
3 = 90 Hz. In the case of the arrangement of FIG. 1, the frequency of coupled vibration between adjacent pipes is as follows.

L1 (m) L2 (m) Coupled vibration frequency (Hz) 1.35 1.06 71 1.35 0.85 77 1.35 0.53 90 1.06 0.85 89 1.06 0 .68 98 0.85 0.68 111 0.85 0.53 123 0.68 0.53 140 According to this, each pipe 18-1 thru | or 18-n sound absorption (63,80,100,125). , 160 Hz is the center), and sound absorbing power is obtained on average in the range of about 60 to 160 Hz.

A 1/5 scale model of the sound absorbing structure 16 shown in FIG. 1 was manufactured and subjected to the JIS in-pipe method (JIS A 140
FIG. 4 shows the result of the normal incidence sound absorption coefficient calculated by obtaining the transfer function between two points using a pseudo-random signal according to 5). Fig. 4 shows the measurement results when the 1/5 scale model is used. Therefore, in the full scale model, the frequency axis is 1 /
It becomes 5. In FIG. 4, the broken line indicates the measurement result when the sound absorbing effect is eliminated by closing the opening 22 of each pipe 18-1 to 18-n with a plate material, and the solid line indicates the measurement result when the opening 22 is completely opened. The dotted chain line is the measurement result when the opening 22 is filled with glass wool as the flow resistance material 26. According to this, in the case of the frequency corresponding to about 60 to 160 Hz in the full scale model, when the opening 22 is completely opened, compared with the case where the opening 22 is closed, the sound absorption force for the area indicated by one-way hatching is shown. By further closing the opening 22 with glass wool, the sound absorbing power for the area indicated by the two-way hatching was increased, and it was confirmed that sufficient sound absorbing power can be obtained in the low sound range.

Next, FIG. 5 shows an example of a method of installing the sound absorbing structure 16 of FIG. 1 in a chamber. This is the sound absorbing structure 1 of FIG.
6 is housed in a box 34 having a size of an ordinary interior panel (910 × 1820 mm) to form a panel 29, which is arranged side by side on a wall 32 of a room 30.
The opening 22 of each pipe 18 is opened upward and communicates with the indoor space 36. It is also possible to cover the front surface of the panel body 29 with a cloth. According to this, 70 from the wall
The sound absorbing structure 29 can be accommodated in a thickness of about mm.
The sound absorbing structure 16 shown in FIG. 1 may be installed on the wall surface without being placed in the box 34.

[0017]

[Other Embodiments] In addition to the wall surface, the sound absorbing structure 16 is shown in FIG.
It can also be installed on the ceiling surface 40, as shown in FIG. Further, as shown in FIG. 7, it can be installed on the wall surface 32 and the ceiling surface 40 in various directions. In addition to horizontally arranging the pipes as an example, the sound absorbing structure 4 shown in FIG.
As in 2, the openings 22 may be arranged radially adjacent to each other.

Further, like the sound absorbing structure 44 shown in FIG. 9, the pipe 18 is housed and fixed in the box 46 with the opening 22 being opened upward, and the shape (dimension: 910 × 1820 mm), and legs and casters 47 are attached to the lower end portion thereof to form a self-supporting panel body. Further, the panel surface itself can be configured as an acoustic panel by configuring the panel surface to be reflective or sound absorbing, or by filling a space inside the box body 46 with a sound absorbing material. Further, like the sound absorbing structure 50 shown in FIG. 10, the pipes 18 may be bundled and attached to the frame 52 to form a self-standing structure. In addition to the panel, the sound absorbing structure can be configured by incorporating a pipe into a fixture, an object, a lighting fixture or the like.

Further, although the length of the pipe itself is made different in the above embodiment, as in the sound absorbing structure 54 shown in FIG.
It is also possible to set the length of the pipe 18 itself to be the same and set the length of the cavity 24 at the position of the closing member 56 to be inserted therein. In this case, if the lower end of the pipe is also the opening 22 ', sound can be absorbed by the cavity 24' below the closing member 56. Alternatively, as in the sound absorbing structure 58 shown in FIG. 12, the pipe 18 may be of a two-stage slide type so that the length of the cavity 24 can be adjusted individually (the position of the opening 22 is fixed). it can.

Further, in the above-described embodiment, the cavity is formed of a pipe, but as in the sound absorbing structure 60 shown in FIG. 13, plate members (side plate 62, bottom plate 70, partition plate 78) are assembled and the opening 22 is formed at one end. It is also possible to configure a plurality of cavities 24 having different lengths and having a rectangular cross section. Further, by using this structure, a panel body can be formed like the sound absorbing structure 59 shown in FIG.

Further, in the above embodiment, the opening 22 is provided at one end of the cavity, but it may be formed on the side surface near the one end like the sound absorbing structure 84 shown in FIG. Further, although the cavity is linear in the above-mentioned embodiment, it may be curved. Further, the sound absorbing structure of the present invention is not limited to the bass range, but can be configured for various bands depending on the length of the cavity.

[0022]

As described above, according to the first aspect of the present invention, sound is absorbed by resonance of each cavity alone and coupled vibration in a plurality of cavities, and the sound absorption is determined by the length of the cavity. Since the frequencies can be absorbed in a concentrated manner, the sound absorption frequency characteristic can be easily set to a desired state. Further, since the sound absorption frequency can be set by the length of the cavity, it is possible to make the thickness thin and relatively compact even when absorbing sound in the low frequency range, and it is also possible to construct it as a general interior panel. .

According to the second aspect of the present invention, since the flow opening material such as glass wool, cloth, gauze or the like is used to close the opening of the cavity having a large air particle velocity or the vicinity thereof, sound absorption is added here. It is possible to increase the sound absorption. According to the third aspect of the present invention, the plurality of cavities are configured along the wall surface of the chamber or the cavities, whereby the space can be efficiently arranged. According to the invention described in claim 4, by constructing the plurality of cavities in the panel body, it is possible to configure a sound absorbing panel having an outer shape equivalent to that of a general interior panel, which facilitates construction. Moreover,
Since the sound absorption frequency characteristic can be set by the length of the cavity,
The panel body can be made thin even when absorbing sound in the low frequency range. According to the invention described in claim 5, the plurality of cavities can be easily configured by configuring the plurality of cavities with pipes, respectively.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional sound absorbing structure.

FIG. 3 is a diagram illustrating a sound absorbing principle of the sound absorbing structure of FIG.

FIG. 4 is a diagram showing measurement results of sound absorption characteristics using the 1/5 scale model of FIG.

5A and 5B are a perspective view and a cross-sectional view showing an installation example of the sound absorbing structure of FIG. 1 on a wall surface of a room.

FIG. 6 is a perspective view showing another embodiment of the present invention.

FIG. 7 is a perspective view showing another embodiment of the present invention.

FIG. 8 is a perspective view showing another embodiment of the present invention.

FIG. 9 is a perspective view showing another embodiment of the present invention.

FIG. 10 is a perspective view showing another embodiment of the present invention.

FIG. 11 is a perspective view showing another embodiment of the present invention.

FIG. 12 is a perspective view showing another embodiment of the present invention.

FIG. 13 is a perspective view showing another embodiment of the present invention.

FIG. 14 is a perspective view showing another embodiment of the present invention.

FIG. 15 is a perspective view showing another embodiment of the present invention.

[Explanation of symbols]

16, 42, 50, 54, 58, 60, 84 Sound absorbing structure 18 (18-1 to 18-n) Pipe 22 Opening 24 (24-1 to 24-n) Cavity 26 Flow resistance material 29, 44, 59 Sound absorbing structure (panel body) 32 Wall surface 40 Ceiling surface 44 Sound absorbing structure (panel body) L Length of cavity

Claims (5)

[Claims] 1. A sound absorbing structure having a structure in which a plurality of cavities having different lengths, one of which is closed and the other of which is opened, are arranged such that the openings on the opened side are adjacent to each other. 2. The position of the opening of the cavity or its vicinity,
The sound absorbing structure according to claim 1, wherein the sound absorbing structure is covered with a flow resistant material having air permeability. 3. The sound absorbing structure according to claim 1, wherein the plurality of cavities are formed along a wall surface or a ceiling surface of the room. 4. The sound absorbing structure according to claim 1, wherein the plurality of cavities are formed in a panel body. 5. The sound absorbing structure according to claim 1, wherein each of the plurality of cavities is formed by a pipe.