Patent Application
20170284088
The present invention relates to sound absorbing structures and acoustic rooms, and more particularly to sound absorbing structures suitable for audio rooms and acoustic rooms provided with the same.
Rooms (audio rooms) primarily intended for playing a musical instrument such as the piano or listening to music are required not only to have sound insulating properties but also to provide great sound (acoustics). One method to create great acoustics is “sound absorption,” and conventionally, there are sound absorbing ceiling materials, sound absorbing wall materials, and wall-mounted or standing sound absorbing panels.
For example, Japanese Unexamined Patent Application Publication No. 2005-146650 (Patent Literature 1) proposes a sound absorbing structure having a plurality of Helmholtz resonators formed in studs disposed in a space in a double wall in order to absorb sounds of a specific frequency in an air layer that is present in the double wall. Specifically, Patent Literature 1 discloses that each stud is formed by a hollow tube extending in the vertical direction, a plurality of openings that open to the space in the wall are formed in a side surface of the stud, and the peripheral portion of each opening has a tubular shape protruding laterally from the remaining portion.
It is known in the field of architectural acoustics that it is effective to place a sound absorbing material in a corner(s) of a room in order to reduce acoustics trouble called booming, namely unbalanced sound due to a build-up of low-pitched sounds in the corner(s) of the room. For example, Japanese Unexamined Patent Application Publication No. 2014-141822 (Patent Literature 2) proposes a technique in which a sound absorber substantially in the shape of a triangular prism is placed in a corner of an acoustic room and a thick part of the sound absorber absorbs sounds in a low frequency range and a thin part of the sound absorber absorbs sounds in a high frequency range. Patent Literature 2 also proposes that a variable mechanism that can change the exposed area of a sound absorbing surface (front surface) of the sound absorber be added so that acoustics can be changed.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2005-146650
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2014-141822
In the case of the substantially triangular prism-shaped sound absorber placed in the corner as in Patent Literature 2, the dimensions of the sound absorber are increased in order to enhance sound absorption performance of the sound absorber. However, if the sound absorber placed in the corner has excessively large dimensions, the space in the room is reduced, and such an excessively large sound absorber is also not desirable in terms of design. Such a sound absorber is therefore not very practical.
The technique of Patent Literature 1 requires studs with a special structure. Accordingly, a technique that improves sound absorption performance with a simple structure is desired.
The present invention was developed to solve the above problems, and it is an object of the present invention to provide a sound absorbing structure that can improve sound absorption performance with a simple structure and an acoustic room.
A sound absorbing structure according to one aspect of the present invention is a sound absorbing structure that absorbs sound and includes: a rear surface member having a length in a predetermined direction; a front surface member that is shorter in the predetermined direction than the rear surface member; and a sound absorbing material that is placed in front of the rear surface member. The front surface member is parallel to the rear surface member and is separated forward from the rear surface member. An opening is formed at a position adjoining the front surface member in the predetermined direction. The sound absorbing material is provided in both a first region located behind the opening and a second region sandwiched between the front surface member and the rear surface member.
A sound absorbing structure according to another aspect of the present invention is a sound absorbing structure that absorbs sound and includes: a rear surface member having a length in a predetermined direction; a front surface member that is parallel to the rear surface member and is separated forward from the rear surface member; and a sound absorbing material that is placed in front of the rear surface member. The front surface member has an opening partially in the predetermined direction. The sound absorbing material is provided in both a first region located behind the opening and a second region located behind a reflecting wall portion. The reflecting wall portion is the front surface member excluding the opening.
Preferably, a part of the sound absorbing material which is located in the first region absorbs sounds in a high frequency range, and a part of the sound absorbing material which is located in the second region absorbs sounds in a low frequency range.
Preferably, a length dimension in the predetermined direction of the second region is larger than that in the predetermined direction of the first region.
More preferably, when the length dimension of the first region is 1, the length dimension of the second region is 2 or more.
It is desirable that the length dimension in the predetermined direction of the second region be larger than a depth dimension of the first region.
It is desirable that the length dimension of the first region be a 0.5 module.
Preferably, the sound absorbing structure further includes: a low-pitched sound acoustics variable mechanism that is disposed in the second region and that can change acoustics in the low frequency range.
Alternatively, the sound absorbing structure may further include: a low-pitched sound acoustics variable mechanism including a partition member that adjusts an opening area of a passage for the sounds in the low frequency range to travel from the first region into the second region.
The partition member may be formed by a plate-like member provided so that its angle with respect to the predetermined direction can be changed. In this case, the second region may include a void where the plate-like member can be rotated.
In particular, in the case where the sound absorbing structure does not include the low-pitched sound acoustics variable mechanism, the sound absorbing material may extend from the first region to the second region.
Preferably, the sound absorbing structure further includes: an acoustics variable mechanism that can change acoustics by adjusting an exposed area of a sound absorbing surface exposed through the opening.
The rear surface member may form at least one of sidewalls, a floor, and a ceiling of a room.
An acoustic room according to still another aspect of the present invention includes one of the above sound absorbing structures.
According to the present invention, sound absorption performance can be improved with a simple structure. Since the thickness of the sound absorbing material need not be increased, practicality can be improved.
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the figures, the same or corresponding portions are denoted with the same reference characters, and description thereof will not be repeated.
First, the outline of an acoustic room according to the present embodiment will be described. In the present embodiment, “front” refers to the side closer to a sound source (the side closer to the center of the room), and “rear” refers to the side farther from the sound source.
Referring to
The rear surface member 21 has a rectangular shape and has a length in the vertical direction and the lateral direction. The rear surface member 21 is perpendicular to the sidewalls 93, 95 of the acoustic room 9. The front surface member 22 is parallel to the rear surface member 21 and is separated forward from the rear surface member 21. The front surface member 22 also has a rectangular shape and has a length in the vertical direction and the lateral direction. Arrow A1 in
The rear surface member 21 and the front surface member 22 are rigid, and the front surface member 22 and the rear surface member 21 form a double wall. That is, both the rear surface member 21 and the front surface member 22 form the sidewall 92.
The front surface member 22 has a smaller lateral width than of the rear surface member 21. An opening 23 is thus formed at the position located in front of the rear surface member 21 and adjoining the front surface member 22 in the lateral direction.
The sound absorbing material 3 is disposed in a region (hereinafter referred to as the “first region”) 24 exposed through the opening 23 and extends also in a region (hereinafter referred to as the “second region”) 25 sandwiched between the rear surface member 21 and the front surface member 22. That is, the sound absorbing material 3 is comprised of a portion (hereinafter referred to as the “exposed sound absorbing portion”) 31 located in the first region 24 and exposed in the room and a portion (hereinafter referred to as the “hidden sound absorbing portion”) 32 located in the second region 25 and hidden by the front surface member 22.
The sound absorbing material 3 may be made of a commonly used sound absorber such as glass wool or rock wool, or may be made of a layered sound absorber comprised of a plurality of layer members as shown in
According to the present embodiment, since the front surface of the front surface member 22 and the front surface of a part (the exposed sound absorbing portion 31) of the sound absorbing material 3 are exposed in the room (acoustic room 9), a part of sound produced in the room is reflected by the front surface member 22, and another part of the sound is incident on the exposed sound absorbing portion 31 of the sound absorbing material 3 through the opening 23 and is absorbed by the exposed sound absorbing portion 31.
In the present embodiment, the sound absorbing material 3 has the hidden sound absorbing portion 32 adjoining the exposed sound absorbing portion 31 in the lateral direction. This allows sounds in a high frequency range (hereinafter sometimes simply referred to as “high-pitched sounds”) to be absorbed by the exposed sound absorbing portion 31 and allows sounds in a low frequency range (hereinafter sometimes simply referred to as “low-pitched sounds”) to be diffracted into the second region 25 and absorbed by the hidden sound absorbing portion 32. Accordingly, sounds in a wide frequency range can be absorbed by the sound absorbing material 3 without increasing the thickness of the sound absorbing material 3.
The configuration (size or proportions) of the sound absorbing structure 1 that can appropriately absorb low-pitched sounds by the sound absorbing material 3 and that achieves balanced absorption of low- to high-pitched sounds will be described below.
As shown in
The thickness dimension D3 of the sound absorbing material 3 is, e.g., 100 mm. The thickness dimension D3 is equal to the depth dimension of the first region 24 and the second region 25. In
Sound absorption performance of the sound absorbing structure 1 having such a configuration will be described with reference to the experimental results using comparative examples. In the experiments, such a layered sound absorber as shown in
First, sound absorption performance (sound absorption capability) of the sound absorbing structure 1 for low-pitched sounds will be described with reference to
The sound absorbing structure 1 of the present embodiment is a “¼-absorption” wall structure as the opening dimension D1 is 0.5 P (about 500 mm). The wall structure 101 shown in
In the graph of
In the “full-absorption” wall structure 102 of
The above results show that the sound absorbing structure 1 having the opening dimension D1 of 0.5 P has excellent sound absorption performance for low-pitched sounds.
Balance of sound absorption of the sound absorbing structure 1 will be described below with reference to
In the sound absorbing structure 1 of the present embodiment, the ratio of the opening dimension D1 to the reflecting wall dimension D2 is 1:3. In the wall structure 104 shown in
In the graph of
In the wall structure 104 in which the “ratio of absorption to reflection is 1:1,” the sound pressure level decreases as the sound pitch increases. The wall structure 104 therefore has poor balance of sound absorption. In the wall structure 105 in which the “ratio of absorption to reflection is 1:2,” balance of sound absorption is improved over the wall structure 101, but the sound pressure level still decreases as the sound pitch increases. On the other hand, in the sound absorbing structure 1 in which the “ratio of absorption to reflection is 1:3” according to the present embodiment, the sound pressure level is substantially constant for low- to high-pitched sounds. The sound absorbing structure 1 thus has uniform sound absorption properties.
The above results show that the sound absorbing structure 1 in which the ratio of the opening dimension D1 to the reflecting wall dimension D2 is 1:3 achieves balanced absorption of low- to high-pitched sounds.
In order to transmit sound into the second region 25 (the hidden sound absorbing portion 32) in the lateral direction, a backing member that supports the rear surface member 21 and the front surface member 22 needs to have a portion extending through the second region 25 in the lateral direction. Specifically, for example, a backing material 4 as shown in
The backing material 4 has a plurality of cutouts 40 formed at intervals in the vertical direction so as to extend though the second region 25 in the lateral direction. In
As shown in
As described above, since the sound absorbing structure 1 of the present embodiment is configured so that low-pitched sounds are absorbed by the hidden sound absorbing portion 32, the thickness of the sound absorbing material 3 need not be increased. A larger space is therefore available in the acoustic room 9, which can improve practicality and design. Moreover, excellent sound absorption performance can be achieved with a simple structure. As a result, comfortable acoustics can be created in the acoustic room 9 provided with the sound absorbing structure 1. The acoustic room 9 can thus be provided as a comfortable audio room.
The configuration (size or proportions) of the sound absorbing structure 1 provided in the acoustic room 9 may be as follows.
The ratio of the opening dimension D1 of the opening 23 to the reflecting wall dimension D2 may be 1:2. That is, it is desirable that, when the opening dimension D1 is 1, the reflecting wall dimension D2 be 2 or more. This is because, in the experimental results shown in
The sound absorption coefficient for each frequency range may vary depending on the material or density of the sound absorbing material 3, but the lateral dimension of the hidden sound absorbing portion 32, namely the reflecting wall dimension D2, need only be equal to or larger than ½ of the wavelength of the sound wave in the low frequency range (125 Hz).
Even when the depth dimension of the second region 25 (and the first region 24) is larger than 100 mm, the lateral dimension of the hidden sound absorbing portion 32 that absorbs low-pitched sounds, namely the reflecting wall dimension D2, is larger than at least the thickness dimension D3 of the exposed sound absorbing portion 31 that absorbs high-pitched sounds, namely the depth dimension of the first region 24 (and the second region 25).
A sound absorbing structure of an acoustic room according to a second embodiment of the present invention will be described below. In the present embodiment, the sound absorbing structure has a function to be able to change acoustics in the low frequency range.
The sound absorbing structure 1A includes a low-pitched sound acoustics variable mechanism 5. The low-pitched sound acoustics variable mechanism 5 can change the sound absorption coefficient for low-pitched sounds by adjusting the opening area of a passage (hereinafter referred to as the “passage area” for sounds in the low frequency range to travel from the first region 24 into the second region 25. That is, the low-pitched sound acoustics variable mechanism 5 can change acoustics in the low frequency range.
The low-pitched sound acoustics variable mechanism 5 typically can be implemented by a plate-like partition member 51. For example, the partition member 51 has a width equal to or larger than the depth dimension of the first region 24 and the second region 25 and has a length substantially equal to the height dimension of the first region 24 and the second region 25 (the height from the floor 91 to the ceiling 96 shown in
In the state of
In order to effectively block or reduce passage of low-pitched sounds into the second region 25 by the partition member 51, it is desirable that the partition member 51 be a rigid plate-like member. This will be described with reference to the experimental results shown in
The experimental results of
As described above, according to the present embodiment, acoustics for low-pitched sounds can be changed. The sound absorbing structure 1A can therefore be made to function as a woofer or a subwoofer by intentionally reducing the sound absorption coefficient for low-pitched sounds. Comfortable acoustics can therefore be created according to the type of musical instrument to be used etc.
The vertical length of the partition portion 51 is substantially the same as the height dimension of the boundary plane 26. However, the vertical length of the partition portion 51 may be smaller than the height dimension of the boundary plane 26. That is, the partition member 51 may be configured to partially open the passage for low-pitched sounds even when the partition member 51 is fully inserted.
The low-pitched sound acoustics variable mechanism 5 may have other configurations. A modification of the low-pitched sound acoustics variable mechanism 5 will be described.
(Modification)
In the low-pitched sound acoustics variable mechanism 5A, the partition member 51 is contained in the second region 25. In this case, the passage area for low-pitched sounds can be adjusted by rotating the partition member 51. That is, the partition member 51 is placed so that the angle with respect to the lateral direction can be changed. It is desirable that the partition member 51 be placed near the inlet of the second region 5 (near the boundary plane 26 described above).
In this case, in order to open and close the passage for low-pitched sounds, the partition member 51 need only be rotatable by 90° about its centerline. The passage is fully closed when the partition member 51 is at 90° with respect to the lateral direction (when the partition member 51 is parallel the thickness direction as in
In the low-pitched sound acoustics variable mechanism 5A, the sound absorbing material 3 may not be provided in the rotation range of the partition member 51 so that the partition member 51 can be rotated in the second region 25. That is, as shown in
In order to easily perform the operation of rotating the partition member 51 from inside the room, the low-pitched sound acoustics variable mechanism 5A may include an operation lever 53 coupled to a rotation shaft of the partition member 51. In this case, an operation opening 220 that exposes the tip end of the operation lever 53 may be formed in a part of the front surface member 22 which is located in front of the void 250.
In the case where the void 250 is formed in the second region 25 as in this modification, the lateral dimensions of the rear surface member 21 and the front surface member 22 may be increased by the lateral width of the void 250 in order to avoid slight degradation in sound absorption capability for low-pitched sounds in a fully open state. The lateral dimension of the hidden sound absorbing portion 32 can thus be made equal to the dimension thereof in the second embodiment.
A sound absorbing structure of an acoustic room according to a third embodiment of the present invention will be described below. In the present embodiment, the sound absorbing structure has a function to be able to change acoustics in the entire frequency range.
The sound absorbing structure 1C includes an acoustics variable mechanism 6. The acoustics variable mechanism 6 can change the overall sound absorption coefficient by adjusting the exposed area of a sound absorbing surface exposed through the opening 23 (that is, the front surface of the exposed sound absorbing portion 31 or the front surface of the decorative panel).
Specifically, the acoustics variable mechanism 6 is disposed in the opening 23, and for example, is formed by a plurality of slats 61 like a louver. Each slat 61 extends in the lateral direction and its angle can be changed in the vertical direction. Accordingly, the exposed area of the sound absorbing surface of the sound absorbing material 3 can be adjusted by changing the angles of the slats 61. That is, when the entire sound absorbing surface or a part of the sound absorbing surface is covered by the slats 61, the overall sound absorption coefficient is reduced, so that acoustics in the entire frequency range are enhanced.
Accordingly, in the present embodiment as well, comfortable acoustics can be created according to the type of musical instrument to be used etc.
The acoustics variable mechanism 6 is not limited to the configuration shown in
The acoustic rooms having sidewalls with a lateral dimension of 2 P are described by way of example in the first to third embodiments. Such a sound absorbing structure as described above is also applicable to acoustic rooms surrounded by sidewalls with other lateral dimensions. An example of the configuration of such an acoustic room will be described below.
For example, the sound absorbing structure 1 described in the first embodiment is used as a single unit, and two sound absorbing structures 1 are arranged in the lateral direction in each of the sidewalls 93, 95 with a lateral dimension of 4 P. In the present embodiment, the two units are arranged so that the positional relationship between the front surface member 22 and the opening 23 in the lateral direction is the same between the two units. In this case, a partition material 71 that blocks passage of sound may be provided between the units.
Alternatively, two sound absorbing structures 1 may be arranged symmetrically in terms of the positional relationship between the front surface member 22 and the opening 23 so that the openings 23 are located near the corners of the acoustic room 9A. In either case, the rear surface member 21 can be continuous between the two sound absorbing structures 1.
For example, the sidewall 92 with a lateral dimension of 3 P is formed by a sound absorbing structure 1D. The sound absorbing structure 1D has an opening 23 with an opening dimension of 0.5 P in front of the middle part of the rear surface member 21 with a lateral dimension of 3 P, and has a pair of front surface members 22 on both sides of the opening 23. In this case as well, the thickness dimension D3 of the sound absorbing material 3 need only be 100 mm or more.
As described above, in the case where the sidewall has a lateral width larger than 2 P, the overall lateral dimension D2 of the front surface members 22 may be larger than 1.5 P.
In the sound absorbing structures of the above embodiments, the front surface member 22 and the opening 23 are located so as to adjoin each other in the lateral direction. However, the front surface member 22 and the opening 23 may be located so as to adjoin each other in the vertical direction. In this case, the opening 23 may be formed in the middle in the vertical direction like the sidewall 92 shown in
In the above embodiments, the rear surface member 21 and the front surface member 22 of the sound absorbing structure form the sidewalls of the acoustic room. However, the rear surface member 21 and the front surface member 22 of the sound absorbing structure may form the floor 91 and the ceiling 96 of the acoustic room, as shown in
Alternatively, only the rear surface member 21 of the sound absorbing structure may form at least one of the sidewalls 92 to 95, the floor 91, and the ceiling 96 of the acoustic room. That is, the front surface member 22 may be merely placed as a reflecting panel in front of a surface (the rear surface member 21) forming the acoustic room.
Alternatively, the sound absorbing structures described in the above embodiments may not be embedded in advance in the acoustic room. That is, the sound absorbing structure may be implemented as such a portable sound absorbing device as shown in
Referring to
In this case, the rear surface member 21 and the front surface member 22 form a part of a housing of the sound absorbing device 10. The sound absorbing device 10 may be surrounded by surface members 81 to 84 covering the upper and lower end faces and both side surfaces of the sound absorbing material 3 as well as by the rear surface member 21 and the front surface member 22.
In the sound absorbing device 10 as well, both the rear surface member 21 and the front surface member 22 have a rectangular shape. Assuming that a predetermined direction shown by arrow A2 in
By installing such a sound absorbing device 10 at a desired position in a room, the room can be used as an audio room. Since the sound absorbing device 10 can change acoustics according to the pitch, the sound absorbing device 10 can function as an audio tune. The sound absorbing device 10 may be installed so that the predetermined direction matches the lateral direction of a sidewall of a room, or may be installed so that the predetermined direction matches the vertical direction of the room.
In the example of the sound absorbing device 10 in
The above embodiments are described with respect to the case where the front surface member 22 is shorter in a predetermined direction (e.g., the lateral direction) than the rear surface member 21 and the opening 23 adjoins the front surface member 22 in the predetermined direction. However, the rear surface member 21 and the front surface member 22 may have the same length in the predetermined direction and the opening 23 may be formed in a part of the front surface member 22. In this case, a region located behind the remaining part (reflecting wall portion) of the front surface member 22, i.e., located behind the front surface member 22 excluding the opening 23, corresponds to the second region described above. As in the above embodiments, the first region is a region located behind the opening 23.
For example, even when the front surface member 22 has the opening 23, the opening 23 is located at one end in a predetermined direction of the front surface member 22 and extends in a direction crossing (perpendicular to) the predetermined direction. More specifically, assuming that the predetermined direction is the lateral direction, the opening 23 may extend from the upper end position to the lower end position of the front surface member 22.
As shown in
In the second embodiment, it is described that the sound absorbing material 3 may be divided in the case where the low-pitched sound acoustics variable mechanism is provided. However, the sound absorbing material 3 may be divided regardless of whether the low-pitched sound acoustics variable mechanism is provided or not. That is, the sound absorbing material 3 need only be provided in both of the first and second regions 24, 25 that form a region located in front of the rear surface member 21. The sound absorbing material 3 may not extend from the first region 24 to the second region 25.
For example, as shown in
Moreover, a void, that is, a portion where there is no sound absorbing material 3 (hidden sound absorbing portion 32), may be formed in the second region 25. In the example of
Alternatively, as shown in
As shown in
Although the embodiments of the present invention are described above, the embodiments and the modifications thereof may be combined as appropriate.
The embodiments disclosed herein are by way of example in all respects and should not be interpreted as restrictive. The scope of the present invention is defined by the claims rather than by the above description, and the invention is intended to cover all changes and modifications within the spirit and scope of the invention as defined by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-192609 | Sep 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/067749 | 6/19/2015 | WO | 00 |
