WO2012081672A1

WO2012081672A1 - Acoustic structure

Info

Publication number: WO2012081672A1
Application number: PCT/JP2011/079062
Authority: WO
Inventors: 本地　由和; 藤森　潤一; 栗原　誠
Original assignee: ヤマハ株式会社
Priority date: 2010-12-15
Filing date: 2011-12-15
Publication date: 2012-06-21
Also published as: KR101452662B1; KR20130050357A

Abstract

[Problem] To reliably prevent the occurrence of acoustic problems within an acoustic space even in an instance in which sound waves in a high-frequency band are being generated within the space. [Solution] This acoustic structure comprises wall members (58, 59, 60-71) that form a plurality of voids (72), a plurality of openings (73) provided to the wall members so as to allow each of the voids (72) to communicate with the exterior space, and a sound-absorbing material (80) that fills at least one void (72-4) from amongst the plurality of voids (72). The sound-absorbing material (80) is exposed to the exterior space from an opening (73-4) that corresponds to the at least one void (72-4). The area of the opening (73-4) that corresponds to the at least one void (72-4) filled with the sound-absorbing material (80) is greater than the area of an opening (73-1) that corresponds to a void (72-1) not filled with the sound-absorbing material (80).

Description

Acoustic structure

The present invention relates to a technique for preventing acoustic disturbance in an acoustic space.

In an acoustic space surrounded by walls such as halls and theaters, acoustic disturbances such as booming and flutter echoes occur due to repeated reflection of sound between parallel facing walls. FIG. 10 is a front view showing a conventional acoustic structure 50 suitable for preventing this type of acoustic disturbance. In this acoustic structure 50, a plurality of rectangular tube-shaped pipes 51-j (j = 1 to 7) each having a different length are arranged in parallel so as to form a plane as a whole. Each pipe 51-j (j = 1 to 7) is made of a reflective material having a high rigidity. Each pipe 51-j (j = 1 to 7) has an opening 52-j (j = 1 to 7) facing the same direction. This acoustic structure 50 has an inner wall, a ceiling, etc. of the acoustic space with the opening 52-j (j = 1 to 7) of each pipe 51-j (j = 1 to 7) facing the center of the acoustic space. Installed.

In such a configuration, each of the pipes 51-j (j = 1 to 7) of the acoustic structure 50 has a specific sound wave among the sound waves incident on the respective openings 52-j (j = 1 to 7) from the acoustic space. Resonates with sound waves of resonance frequency. Along with this resonance, sound waves radiated from the cavities in the pipes 51-j (j = 1 to 7) to the acoustic spaces through the openings 52-j (j = 1 to 7) are transmitted to the pipes 51-j ( The sound absorption effect and the scattering effect are generated in the vicinity of each opening 52-j (j = 1 to 7) of j = 1 to 7). As a result, sound waves propagating from the acoustic space toward the pipe 51-j (j = 1 to 7) are dissipated in the pipe 51-j (j = 1 to 7), and acoustic disturbances such as booming and flutter echo occur. Is prevented. In addition, this kind of acoustic structure 50 is disclosed by patent document 1, for example.

JP 2002-30744 A JP 2010-84509 A

In this type of acoustic structure 50, the sound absorption effect and the scattering effect are generated at the resonance frequency determined by the structure of each of the pipes 51-j (j = 1 to 7). Here, each pipe 51-j (j = 1 to 7) has a higher-order resonance mode in addition to the fundamental mode. Therefore, it is possible not only to resonate each pipe 51-j (j = 1 to 7) in the fundamental mode but also to obtain a sound absorption effect and a scattering effect over a wide band by resonating in a higher order mode. It is.

However, in reality, the pipe 51-j of the acoustic structure 50 has a low sound absorption effect and scattering effect generated when a sound wave in a high frequency band, particularly a frequency band of 2 kHz to 4 kHz is incident on the opening 52-j. This is smaller than the sound absorption effect and the scattering effect generated when the sound wave in the frequency band is incident on the opening 52-j. For this reason, when a sound wave in a high frequency band is generated in the acoustic space, the acoustic energy of the sound wave cannot be sufficiently dissipated by the pipe 51-j.

The present invention has been made in view of the above points, and even when a sound wave in a high frequency band is generated in an acoustic space, an acoustic structure capable of reliably preventing the occurrence of an acoustic failure in the space. Is to provide.

The acoustic structure according to the first aspect of the present invention is an acoustic structure in which a cavity is formed and an opening is provided in a wall member surrounding the cavity, and the side of the plate that does not face the cavity A sound absorbing material is affixed to a region excluding the vicinity of the opening and the opening on the surface. According to the present invention, when a sound wave in a high frequency band where the sound absorption effect and the scattering effect hardly occur is incident, the acoustic energy of the sound wave is lost by the sound absorbing material. Therefore, even when a sound wave in a high frequency band is generated in the acoustic space, it is possible to reliably prevent the occurrence of an acoustic failure in the space.

The acoustic structure according to the second aspect of the present invention includes a wall member that forms a plurality of cavities, and a plurality of openings provided in the wall member so that each of the plurality of cavities communicates with an external space. And a sound absorbing material filled in at least one of the plurality of cavities, wherein the sound absorbing material is exposed to an external space from an opening corresponding to the at least one cavity. An acoustic structure is provided. In this case as well, when a sound wave in a high frequency band where the sound absorption effect and the scattering effect are difficult to occur is incident, the acoustic energy of the sound wave is lost by the sound absorbing material. Even in such a case, it is possible to reliably prevent the occurrence of acoustic disturbance in the space. Furthermore, according to the acoustic structure according to the second aspect, the thickness of the acoustic structure itself can be made uniform, and the sound absorbing material can be peeled off from the wall member to generate the sound absorbing effect and the scattering effect. The problem of disappearance can also be prevented.

It is the left view, front view, and right view which show the acoustic structure which is 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the cavity of the acoustic structure. It is a figure which shows the principle of generation | occurrence | production of the sound absorption effect and the scattering effect by the acoustic structure. It is the left view, front view, and right view which show the acoustic structure which is 2nd Embodiment of this invention. It is the left view, front view, and right view which show the acoustic structure which is 3rd Embodiment of this invention. It is the front view and sectional drawing which show the acoustic structure which is 4th Embodiment of this invention. It is a figure which shows the shape of the opening part of the acoustic structure which is other embodiment of this invention. It is a front view which shows the acoustic structure which is other embodiment of this invention. It is the front view and sectional drawing of a door with an articulation panel function which are other embodiments of this invention. It is a front view which shows the conventional acoustic structure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1A is a left side view showing an acoustic structure 10 according to the first embodiment of the present invention. FIG. 1B is a front view showing the acoustic structure 10. FIG. 1C is a right side view showing the acoustic structure 10. In this acoustic structure 10, plates (wall members) 11-n (n = 1 to 7), 20, and 23 are interposed between two plates (wall members) 18 and 19 that are opposed to each other with a space therebetween. ing. The plates (wall members) 18, 19, 11-n (n = 1 to 7), 20, and 23 are made of a rigid body such as a steel material. The plates (wall members) 11-n (n = 1 to 7), 20, and 23 are cavities 22-i (i = 1 to 6) extending in the left-right direction in the space between the

plates

18 and 19. The plates 20 and 23 block the left and right ends of the cavity 22-i (i = 1 to 6). Hereinafter, “wall members” (18, 19, 11-n (n = 1 to 7), 20, and 23) are simply referred to as “plates”.

The plate 18 of the acoustic structure 10 is provided with openings 21-i (i = 1 to 6). Each opening 21-i in the opening 21-i (i = 1 to 6) of the plate 18 is a cavity 22 surrounded by the

plates

18, 19, 11-i, 11- (i + 1), 20, and 21. -I serves to communicate with an acoustic space that is a room space in which the acoustic structure 10 is installed. Further, on the surface of the plate 18 that does not face the cavity 22-i (i = 1 to 6) (that is, the outer surface, the surface on which sound waves are incident: hereinafter referred to as the reflective surface ref). The sound absorbing material 30-m (m = 1 to 7) is attached. The role of the sound absorbing material 30-m (m = 1 to 7) will be described later.

The acoustic structure 10 is installed on the inner wall or ceiling of the acoustic space with the plate 18 having the openings 21-i (i = 1 to 6) facing the center of the acoustic space. When the acoustic structure 10 is installed with the plate 18 facing the center of the acoustic space, the acoustic structure 10 generates a sound absorption effect and a scattering effect, and the acoustic energy of the sound wave propagated from the acoustic space toward the acoustic structure 10 is generated. Dissipate in the plate 18. The principle of generation of the sound absorption effect and the scattering effect by the acoustic structure 10 is as described below.

As shown in the cross-sectional view of FIG. 2, the cavity 22-i behind one opening 21-i in the acoustic structure 10 has an opening 21-i as an opening end and an end on the left side of the cavity 22-i. And the acoustic tube CLP-b having the opening 21-i as the opening end and the right end of the cavity 22-i as the closing end. it can. When a sound wave enters the cavity 22-i from the acoustic space via the opening 21-i, the opening end (opening 21-i) of the acoustic tube CLP-a is closed to the closed end (cavity 22) in the cavity 22-i. -A traveling wave toward the left end of i) and a traveling wave toward the closed end (the right end of the cavity 22-i) from the open end (opening 21-i) of the acoustic tube CLP-b are generated. To do. Then, the former traveling wave is reflected at the closed end of the acoustic tube CLP-a, and the reflected wave returns to the opening 21-i. The latter traveling wave is reflected at the closed end of the acoustic tube CLP-b, and the reflected wave returns to the opening 21-i.

In the acoustic tube CLP-a, resonance occurs at the resonance frequency fa _n (n = 1, 2,...) Shown in the following formula (1), and the traveling wave and the reflected wave are synthesized in the acoustic tube CLP-a. The sound wave is a standing wave having a particle velocity node at the closed end of the acoustic tube CLP-a and a particle velocity antinode at the open end. In the acoustic tube CLP-b, resonance occurs at the resonance frequency fb _n (n = 1, 2,...) Shown in the following formula (2), and the traveling wave and the reflected wave are synthesized in the acoustic tube CLP-b. The acoustic wave becomes a standing wave having a particle velocity node at the closed end of the acoustic tube CLP-b and a particle velocity antinode at the open end. In the following formulas (1) and (2), La is the length in the extending direction of the acoustic tube CLP-a (the length from the left end of the cavity 22-i to the opening 21-i), Lb Is the length of the acoustic tube CLP-b in the extending direction (the length from the right end of the cavity 22-i to the opening 21-i), c is the propagation velocity of the sound wave, and n is an integer of 1 or more .
fa _n = (2n−1) · (c / (4 · La)) (n = 1, 2,...) (1)
fb _n = (2n−1) · (c / (4 · Lb)) (n = 1, 2...) (2)

Here, the component of the resonance frequency fa _n of waves incident on the vicinity of the opening portion 21-i at the opening 21-i and the reflective surface ref from acoustic space (surface not facing the cavity 22-i of the plate 18) When attention is paid, the sound wave reflected at the closed end of the acoustic tube CLP-a and radiated from the opening 21-i to the acoustic space is a sound wave having a phase opposite to the sound wave incident on the opening 21-i from the acoustic space. It becomes. On the other hand, in the vicinity of the opening 21-i on the reflection surface ref, the incident wave from the acoustic space is reflected without phase rotation.

Therefore, as shown in FIG. 3, when a sound wave including a component of the resonance frequency fa _n (n = 1, 2,...) Is incident on the cavity 22-i through the opening 21-i, As seen from the incident direction (sound absorption region in FIG. 3), sound waves emitted from the acoustic tube CLP-a through the opening 21-i and points near the opening 21-i on the reflection surface ref. The reflected sound waves are out of phase and interfere with each other, producing a sound absorbing effect. In the scattering region where the sound wave from the opening 21-i and the reflected wave from the reflection surface ref are adjacent to each other, the phases of the sound wave from the opening 21-i and the reflection wave from the reflection surface ref are discontinuous. . When waves having such a phase difference are adjacent to each other, a gas molecule flow is generated in the vicinity of the scattering region so as to eliminate the phase discontinuity. As a result, in the vicinity of the scattering region, acoustic energy flows in a direction other than the specular reflection direction with respect to the incident direction, and a scattering effect occurs. Similarly, when a sound wave including a component of the resonance frequency fb _n (n = 1, 2,...) Is incident on the cavity 22-i through the opening 21-i, the mirror surface is reflected in the direction of incidence on the opening 21-i. A sound absorbing effect occurs in the direction of reflection (sound absorbing region in FIG. 3). In addition, a scattering effect occurs near the scattering region.

In the frequency band of each vicinity of the resonance frequency fa _n and fb _n, even deviated from the resonant frequency fa _n or fb _n, the closer the frequency is to some extent, is radiated into the acoustic space from the opening 21-i The phase of the sound wave to be transmitted and the phase of the reflected wave radiated from the reflection surface ref to the acoustic space have a relationship close to an opposite phase. Therefore, in the frequency band of each vicinity of the resonance frequency fa _n and fb _n, sound absorbing effect and scattering effect of degree depending on the proximity of the frequency to the resonant frequency fa _n or fb _n occurs.

The above is the details of the principle of the sound absorption effect and the scattering effect. As described above, although the sound absorption effect and the scattering effect are also generated for the sound wave in the high frequency band, the magnitude of the effect is smaller than that of the effect in the low frequency band. The sound absorbing material 30-m (m = 1 to 7) in FIG. 1 plays a role of compensating for such a lack of sound absorbing effect and scattering effect in the high frequency band. The sound absorbing material 30-m (m = 1 to 7) has a plurality of small pieces of a material (for example, a porous material) having an absolute value | ζ | The following two conditions a. b. Affixed at a position satisfying

[Condition a. ] A position in a region excluding a region near the opening 21-i (i = 1 to 6) on the reflection surface ref of the plate 18. More specifically, the apertures 21-i (i = 1 to 6) in the reflection surface ref of the plate 18 and their respective so as to generate a scattering region around each aperture 21-i (see FIG. 3). The sound absorbing material 30-m (m = 1 to 7) is pasted to a position outside the area including the vicinity (any position in the surrounding area).

[Condition b. ] Each position where each of the plurality of sound absorbing materials 30-m (m = 1 to 7) is attached is dispersed so that a sufficient distance is provided between the sound absorbing materials 30-m (m = 1 to 7). .

As described above, in the present embodiment, when a sound wave in a high frequency band that hardly generates the sound absorption effect and the scattering effect is incident on the plate 18 having the openings 21-i (i = 1 to 6) and the reflection surface ref. The sound wave is absorbed by the sound absorbing material 30-m (m = 1 to 7) attached to the reflecting surface ref. Therefore, it is possible to reliably prevent the occurrence of acoustic disturbances such as booming and flutter echo for sound waves in a wide frequency band from the low frequency band to the high frequency band.

Further, in the present embodiment, the sound absorbing material 30-m (m = 1 to 7) is attached to the area excluding the area near the opening 21-i (i = 1 to 6) on the reflection surface ref. Therefore, the sound absorbing material 30-m (m = 1 to 7) prevents the radiation of the reflected wave having the same phase as the incident wave from the region near the opening 21-i (i = 1 to 6) on the reflection surface ref. There is nothing. Therefore, it is possible to generate the sound absorption effect and the scattering effect equivalent to the case where the sound absorbing material 30-m (m = 1 to 7) is not attached to the reflecting surface ref.

Further, in this embodiment, the sound absorbing material 30-m (m = 1 to 7) is a small piece, and the sound absorbing material 30-m (m = 1 to 7) has a sufficient distance between each other. It is dispersed and affixed. Sound waves reflected at each point around each of the sound absorbing material 30-m (m = 1 to 7) on the reflecting surface ref are incident on the sound absorbing material 30-m (m = 1 to 7) by diffraction after reflection. Absorbed by the sound absorbing material 30-m (m = 1 to 7). Therefore, the sound absorption rate per unit area can be made higher than when the sound absorbing material 30-m (m = 1 to 7) is stuck together at one place on the reflecting surface ref.

Second Embodiment
FIG. 4A is a left side view showing an acoustic structure 10A according to the second embodiment of the present invention. FIG. 4B is a front view showing the acoustic structure 10A. FIG. 4C is a right side view showing the acoustic structure 10A. 4A, FIG. 4B, and FIG. 4C, the same elements as those of the acoustic structure 10A (FIGS. 1A, 1B, and 1C) are the same. The code | symbol is attached | subjected. In this acoustic structure 10A, a position corresponding to the opposite side of the plates 11-2, 11-3, 11-4, 11-5, and 11-6 on the reflection surface ref of the plate 18 (corresponding to the side surface of the plate 11). At positions, strip-shaped

sound absorbing materials

32, 33, 34, 35, and 36 parallel to the plates 11-2, 11-3, 11-4, 11-5, and 11-6 are attached. That is, the plurality of longitudinal sound absorbing materials 32 to 36 are arranged at a predetermined interval so as not to overlap the positions of the openings 21-1 to 21-7.

Also according to the present embodiment, it is possible to reliably prevent the occurrence of acoustic disturbance in the acoustic space for sound waves in a wide frequency band from a low frequency band to a high frequency band.

<Third Embodiment>
FIG. 5A is a left side view showing an acoustic structure 10B according to the third embodiment of the present invention. FIG. 5B is a front view showing the acoustic structure 10B. FIG. 5C is a right side view showing the acoustic structure 10B. 5A, FIG. 5B, and FIG. 5C, the same reference numerals are used for the same elements as those of the acoustic structure 10B (FIGS. 1A, 1B, and 1C). Is attached. In the acoustic structure 10B, the entire surface of the region excluding the opening 21-i (i = 1 to 6) and the vicinity of the opening 21-i (i = 1 to 6) on the reflection surface ref of the plate 18 The sound absorbing material 38 is affixed.

<Fourth embodiment>
FIG. 6A is a front view showing an acoustic structure 10C according to the fourth embodiment of the present invention. 6B is a cross-sectional view taken along the line BB ′ of FIG. FIG. 6C shows the C-
It is C 'sectional view. In the acoustic structures 10, 10 A, and 10 B according to the first to third embodiments, the sound absorbing material is pasted on the plate 18. On the other hand, in the acoustic structure 10C according to the present embodiment, the inside of the six

plates

58, 59, 60, 61, 62, 63 forming the outer shell of the acoustic structure 10C has nine cavities 72-k ( k = 1 to 9), and the sound absorbing material 80 is loaded into the cavity 72-4 of the nine cavities 72-k (k = 1 to 9). 73-4 is exposed to the external acoustic space. More specifically, in this acoustic structure 10C, plates 60 to 71 are interposed between two

plates

58 and 59 facing in the vertical direction. Of the plates 60 to 71, the

plates

60 and 61 face each other in the left-right direction with a distance D1 equal to the width in the left-right direction of the plate 58 between them. The plates 62 and 63 face each other in the front-rear direction with a distance D2 that is the same as the width in the front-rear direction of the plate 58 therebetween. Between the plates 62 and 63, the

plates

64, 65, 66, 67 and 68 are arranged with a distance D3 between adjacent ones. Further, a plate 69 is disposed at a position between the plate 64 and the plate 65 away from the plate 61 by a distance D4. A plate 70 is disposed at a position between the plate 66 and the plate 67 away from the plate 61 by a distance D5. A plate 71 is disposed between the plate 67 and the plate 68 at a position separated from the plate 61 by a distance D6.

The plate 58 of the acoustic structure 10C is provided with openings 73-k (k = 1 to 9). Of these openings 73-k (k = 1 to 9), the openings 73-1, 73-2, 73-3, 73-5, 73-6, 73-7, 73-8, 73-9 are A square shape having the same vertical width and horizontal width as the distance D3 between the plates 62 and 64 is formed. The opening 73-4 has a rectangular shape having the same vertical width as the distance D3 between the plates 62 and 64 and the same horizontal width as the distance D1 between the

plates

20 and 21.

The opening 73-1 serves to communicate the cavity 72-1 surrounded by the

plates

58, 59, 60, 61, 62, and 64 with an external acoustic space. The cavity 72-2 surrounded by 59, 60, 64, 65, 69 serves to communicate with an external acoustic space. The opening 73-3 serves to communicate the cavity 72-3 surrounded by the

plates

58, 59, 61, 64, 65, and 69 with the external acoustic space. The cavity 72-5 surrounded by 59, 60, 66, 67 and 70 serves to communicate with the external acoustic space. The opening 73-6 serves to communicate the cavity 72-6 surrounded by the

plates

58, 59, 61, 66, 67, and 70 with the external acoustic space, and the opening 73-7 includes the

plates

58, 59, The cavity 72-7 surrounded by 59, 60, 67, 68 and 71 serves to communicate with the external acoustic space. The opening 73-8 serves to communicate the cavity 72-8 surrounded by the

plates

58, 59, 61, 67, 68, 71 with the external acoustic space, and the opening 73-9 includes the

plates

58, 59, The cavity 72-9 surrounded by 59, 60, 61, 63 and 68 serves to communicate with the external acoustic space. The opening 73-4 serves to communicate the cavity 72-4 surrounded by the

plates

58, 59, 60, 61, 65, 66 with the external acoustic space. A sound absorbing material 80 is loaded in the cavity 72-4 at the back of the opening 73-4, and the sound absorbing material 80 is exposed to the acoustic space through the opening 73-4. In addition, the portion of the sound absorbing material 80 exposed from the opening 73-4 is substantially flush with the plate 58 provided with the opening 73-4 (the exposed surface of the sound absorbing material 80 is flush with the surface of the plate 58). About the same height). The above is the details of the configuration of the acoustic structure 10C.

According to this, the openings 73-1 to 73-3 and 73-5 to 73-7 in which the sound absorbing material 80 is not provided form a sound absorbing region in the same manner as the opening 21-i shown in FIG. Acts as follows. That is, sound absorbing regions around the openings 73-1 to 73-3 and 73-5 to 73-7 are created by the action of the sound absorbing material 80 exposed from the opening 73-4. As illustrated, when the area of the opening 73-4 is larger than the areas of the other openings (73-1 to 73-3, 73-5 to 73-7), a plurality of other openings It is possible to widen the sound absorption region that can extend to (73-1 to 73-3, 73-5 to 73-7).

Further, in this acoustic structure 10C, no sound absorbing material is affixed to the plate 58 of the acoustic structure 10C, and some of the nine cavities 72-k (k = 1 to 9) are the cavities 72-4. A sound absorbing material 80 is loaded therein. The sound absorbing material 80 is exposed to the acoustic space through the opening 73-4. Therefore, according to the acoustic structure 10C, the thickness of the acoustic structure 10C itself can be made uniform. Further, it is possible to prevent the problem that the sound absorbing material is peeled off from the plate 58 and the sound absorbing effect and the scattering effect cannot be generated.

Although some embodiments of the present invention have been described above, there may be other embodiments (modifications) in the present invention. For example, it is as follows.

(1) In the first to third embodiments, the number of the cavities 22-i of the acoustic structures 10, 10A, 10B may be 7 or more, or 5 or less. Further, the width of each of the cavities 22-i may be changed.

(2) In the first to third embodiments, a material other than the porous material may be used as the sound absorbing material 30-m (m = 1 to 7), 31, 32, 33, 34, 35, 36, 37. Good.

(3) In the first to third embodiments, one cavity 22-i may be surrounded by five or less plates, or one cavity 22-i may be composed of seven or more plates. It is good also as a structure which is surrounded.

(4) In the third embodiment, the cavity 22-i has a square shape, and the region where the sound absorbing material 38 in the vicinity of the opening 22-i on the reflection surface ref is not attached is more than the space 22-i. It was a square shape. However, the area where the cavity 22-i and the sound absorbing material 38 in the vicinity thereof are not attached may have a shape other than a square (for example, a perfect circle or a shape in which four corners of a square are curved). In this case, as shown in FIG. 7A and FIG. 7B, the area AR where the sound absorbing material 38 in the vicinity of the opening 22-i is not pasted is set on each inner circumference IN of the area AR. The shortest distance from the point to the outer periphery OUT of the opening 22-i may be uniform. Further, the outer periphery OUT of the opening 22-i and the inner periphery IN of the area AR where the sound absorbing material 38 in the vicinity of the opening 22-i is not attached may be formed in different shapes. For example, as shown in FIG. 7C, the outer periphery OUT of the opening 22-i has a square shape, and the inner periphery IN of the area AR where the sound absorbing material 38 in the vicinity of the opening 22-i is not attached. As a shape in which the four corners of the square are curved, the shortest distance from each point on the inner periphery IN of the area AR to the outer periphery OUT of the opening 22-i may be uniform.

(5) In the first to third embodiments, the cut surface parallel to the plate 18 in at least one of the openings 21-i (i = 1 to 6) (for example, the opening 21-1). The area S _o (that is, the area of the opening) is preferably smaller than the area S _p (that is, the cross-sectional area of the cavity) of the cut surface perpendicular to the plate 18 in the cavity 22-1. This is because according to the acoustic structure 10D in which the area S _o is smaller than the area S _p , the sound absorption effect and the scattering effect can be generated in a wider band.

By reducing the area S _o than the area S _p, why can generate sound absorbing effect in a wide band is as follows. As described above, the sound absorption effect is obtained when sound waves having resonance frequencies fa _n and fb _n of the resonance tubes CLP-a and CLP-b in the acoustic structure 10 and frequencies in the vicinity thereof are incident on the acoustic structure 10. This is an effect generated when the phase of the sound wave radiated from the opening 21-i to the acoustic space and the phase of the reflected wave radiated from the reflecting surface ref to the acoustic space are close to each other. Accordingly, the sound wave that enters the acoustic structure 10 through the opening 21-i of the acoustic structure 10 and the reflected wave that is reflected from the opening 21-i toward the incident direction of the sound wave have an inverse phase relationship. The wider the frequency band that is closer, the wider the band in which the sound absorption effect occurs.

Here, a sound wave is perpendicularly directed from the second medium (for example, air in the acoustic space) toward the first medium (for example, air in the opening 21-i or a rigid body that is a material of the acoustic structure 10). When incident, the amplitude and phase of the reflected wave reflected from the boundary surface bsur of both media in the incident direction are expressed by the specific acoustic impedance ratio ζ (ζ = r + jx: r = Re (ζ), x = Im ( It depends on ζ)). More specifically, when the absolute value | ζ | of the specific acoustic impedance ratio ζ of the boundary surface bsur is less than 1, the boundary surface bsur is within ± 180 ° with respect to the sound wave incident on the boundary surface bsur. A reflected wave having a phase difference of is emitted. If Im (ζ)> 0, the smaller the absolute value | Im (ζ) | of the imaginary part Im (ζ) of the specific acoustic impedance ratio ζ, the closer the phase difference approaches + 180 °, and Im (ζ) < If 0, the phase difference approaches -180 ° as the absolute value | Im (ζ) | of the imaginary part Im (ζ) of the specific acoustic impedance ratio ζ decreases.

Furthermore, the area ratio rs (rs = S _o / S _p ) between the area S _o of the cut surface of the opening 21-i and the area S _p of the cut surface of the cavity 22-i is larger than 1 (that is, S _o > S _p ) and the frequency characteristics of the imaginary part Im (ζ) of the specific impedance ratio ζ in each of the case where the area ratio rs is smaller than 1 (that is, S _o <S _p ), the latter is better than the former. The band where the imaginary part Im (ζ) in the frequency characteristic is a certain value (for example, Im (ζ) = 1) is wide (for the relationship between the area ratio rs and the frequency characteristic of the imaginary part Im (ζ)) Reference 2 (see in particular FIG. 9)). Therefore, as the area S _o is smaller than the area S _p, a reflected wave having a phase difference close to a reverse phase with respect to the sound wave incident on the opening 22-1 is spread over a wider band. Can radiate from. For the above reasons, the sound absorption effect can be generated in a wider band by making the area S _o smaller than the area S _p .

(6) In the fourth embodiment, the number of the cavities 72-k of the acoustic structure 10C may be 2 to 8, or 10 or more. In the fourth embodiment, the width of the cavity 72-4 in which the sound absorbing material 80 is loaded is set to the same width as the other cavities 72-1 to 72-3 and 72-5 to 72-9. And the width may be different. Further, as in the acoustic structure 10C ′ shown in FIG. 8, the left-right direction of the opening 73-4 that plays a role of communicating the cavity 72-4 with the outside rather than the width D1 of the cavity 72-4 itself in the left-right direction. The width D7 may be shortened. In this case, the sound absorbing material 80 is loaded only in the space just below the opening 73-4 in the cavity 72-4 so that a sealed space is formed on the left and right sides of the sound absorbing material 80 in the cavity 72-4. May be. Further, two or more cavities 72 may be filled with the sound absorbing material 80.

(7) In the fourth embodiment, a material other than the porous material may be used as the sound absorbing material 80.

(8) In the fourth embodiment, the cavity 72-4 in which the sound absorbing material 80 is loaded has a shape extending in the left-right direction. However, the cavity 72-4 may have a shape extending in the front-rear direction or a shape extending in an oblique direction. Moreover, it is good also as a shape which combined those shapes.

(9) You may comprise the door provided with the acoustic structure 10C in the said 4th Embodiment on both surfaces or one side. FIG. 9 is a front view of a door 10E with a sound control panel function, which is an example of a door provided with an acoustic structure 10C on both sides, and a cross-sectional view taken along line E-E '. In the door 10E with the sound control panel function, the front plate 5F and the rear plate 5B (not shown) are overlapped with a space, and the

plates

6U, 6D, 7L, and 7R are joined to the upper, lower, left, and right edges of the plates 5F and 5B. It is a thing. A door knob NB is provided on the front plate 5F and the rear plate 5B of the door 10E. Further, a space surrounded by the

plates

5F, 5D, 6U, 6D, 7L, and 7R in the door 10E is divided into nine cavities 1-k (k = 1 to 9). Further, of these cavities 1-k (k = 1 to 9), the cavities 1-3 have a cavity 1′-3 and a plate on the plate 5F side with an intermediate plate 5C parallel to the plates 5F and 5B interposed therebetween. 5B-side cavity 1 "-3. The plate 5F has an opening 2- that communicates the cavity 1-1, 1-2, 1'-3, 1-4, 1-9 with the outside. 1, 2-2, 2'-3, 2-4, 2-9 are provided. The plate 5B has cavities 1 "-3, 1-5, 1-6, 1-7, 1-8. Are provided with openings 2 ″ -3, 2-5, 2-6, 2-7, 2-8. In this door 10E, the sound absorbing material 3 ′ is placed in the cavity 1′-3. The sound absorbing material 3 'is exposed to the outside through the opening 2'-3. The sound absorbing material 3 "is loaded in the cavity 1" -3. "" Open 2 "-3 through the outside According to the door 10E with the sound control panel function, a sound absorbing effect and a scattering effect can be generated in each of the two acoustic spaces separated by the door 10E. The sound absorbing materials 3 ′ and 3 ″ and the plate 5C may be made of a transparent or translucent material so that light can pass through.

Claims

A wall member forming a plurality of cavities;
A plurality of openings provided in the wall member to communicate each of the plurality of cavities with an external space;
A sound absorbing material filled in at least one of the plurality of cavities, wherein the sound absorbing material is exposed to an external space from an opening corresponding to the at least one cavity. Structure.
The acoustic according to claim 1, wherein an area of the opening corresponding to the at least one cavity filled with the sound absorbing material is larger than an area of the opening corresponding to the cavity not filled with the sound absorbing material. Structure.
3. The acoustic structure according to claim 1, wherein a surface of the sound absorbing material exposed from the opening is substantially the same height as a surface of the wall member provided with the opening.
The acoustic structure according to claim 1 or 2, wherein a porous material is used as the sound absorbing material.
A door comprising the acoustic structure according to claim 1 or 2 on at least one side.
A door comprising the acoustic structure according to claim 1 or 2 on both sides.
Each sound absorbing material in each acoustic structure provided on each surface of the door has an overlapping arrangement, and a wall member at a portion that partitions both sound absorbing materials has a transparent or translucent portion. Item 6. The door according to Item 5.
An acoustic structure in which a cavity is formed and an opening is provided in a wall member surrounding the cavity, the vicinity of the opening on the surface of the plate not facing the cavity, and the opening An acoustic structure characterized in that a sound-absorbing material is affixed to the area excluding.
The acoustic structure according to claim 1, wherein the sound absorbing material is affixed to the opening and an outer region near the opening so as to generate a scattering region around the opening.
The acoustic structure according to claim 8 or 9, wherein a plurality of sound-absorbing materials are attached to the region with an interval between them.