WO2023199667A1

WO2023199667A1 - Sound-absorbing member, sound-absorbing panel, and sound-absorbing wall

Info

Publication number: WO2023199667A1
Application number: PCT/JP2023/009220
Authority: WO
Inventors: 蔵酒五味; 優大平良; 晴洋江連; 匡人河村; 博之伊藤
Original assignee: ピクシーダストテクノロジーズ株式会社
Priority date: 2022-04-11
Filing date: 2023-03-10
Publication date: 2023-10-19
Also published as: JP7246053B1; JP2023155870A; JP2023155665A

Abstract

A sound-absorbing unit 10 has: hollow parts surrounded by an outer shell that is optically transmissive; and holes that connect the insides and outsides of the hollow parts.

Description

Sound absorbing members, sound absorbing panels and sound absorbing walls

The present disclosure relates to technology for reducing sound through sound absorption.

Suppressing noise generated in railways, expressways, construction sites, indoor spaces, etc. is one of the important social issues. Patent Document 1 discloses that sound is absorbed by fixing a sound absorbing panel to a wall surface.

JP2012-077480A

When sound absorbing members are installed on the interior or exterior of a building, or on equipment, the appearance of the building or equipment to which it is installed changes. In particular, if a sound absorbing member is attached to a wall surface such as glass that has light transmittance and the light transmittance is lost, the functionality and design of the wall surface will be impaired.

An object of the present disclosure is to realize a sound absorbing member suitable for use on a wall surface having light transmittance such as glass.

According to one aspect of the present disclosure, the sound absorbing member includes a cavity surrounded by a light-transmitting outer shell, and a perforation that communicates the inside and outside of the cavity.

It is a figure showing the structure of a sound absorption unit. It is a figure showing the structure of a sound absorption unit. It is a figure showing the structure of a chamber member. It is a figure showing the structure of a chamber member. It is a figure explaining the function of a sound absorption unit. It is a figure which shows the example of use of a sound absorption unit. It is a figure which shows the example of use of a sound absorption unit. FIG. 2 is a diagram showing an example of the configuration of a design device. It is a figure which shows the design process of the sound absorption unit by a design device. It is a figure which shows the modification of the structure of a sound absorption unit. It is a figure which shows the modification of the structure of a sound absorption unit. It is a figure which shows the modification of the structure of a chamber member. It is a figure which shows the modification of the structure of a chamber member. It is a figure which shows the modification of the structure of a perforated plate.

Hereinafter, examples of embodiments of the present invention will be described in detail based on the drawings. Note that, in the drawings for explaining the embodiments, repeated explanations of the same components will be omitted.

(1) Structure of Sound Absorption Unit (1-1) Basic Structure of Sound Absorption Unit The basic structure of the sound absorption unit 10 will be explained. The sound absorption unit 10 includes a specific sound absorption structure that has a sound absorption effect of reducing the sound pressure of reflected and transmitted sound by converting or canceling the energy of the sound waves traveling toward the sound absorption unit 10 into other energy. It is a sound absorbing member. FIGS. 1A and 1B are a perspective view and a front view, respectively, showing the structure of a sound absorption unit according to an embodiment. FIGS. 2A and 2B are a side view and a bottom view, respectively, showing the structure of the sound absorption unit according to the embodiment.

In the following description, the "D direction" is the depth direction (thickness direction) of the sound absorbing unit 10. The sound absorption unit 10 mainly absorbs sound waves traveling in the D direction. The “H direction” is a direction substantially perpendicular to the D direction, and is the height direction of the sound absorption unit 10. The “W direction” is a direction perpendicular to the “D direction” and the “H direction” and is the width direction of the sound absorption unit 10. The sound absorption unit 10 has a plurality of cavities (hereinafter referred to as "waveguides") through which sound waves can enter through perforations, and each waveguide functions as a resonator.

As shown in FIG. 1, the sound absorption unit 10 includes a perforated plate 20, which is a plate-like member with perforations formed therein, and a chamber member 40, which forms a cavity when combined with the perforated plate 20. On the surface of the perforated plate 20, there are perforated regions 21 to 27 in which a plurality of perforations are formed, and non-perforated regions 31 to 36 in which no perforations are formed. The sound absorbing unit 10 has a polygonal (specifically hexagonal) shape when viewed from the −D direction.

FIGS. 3(a) and 3(b) are a perspective view and a front view, respectively, showing the structure of the chamber member according to the embodiment. FIGS. 4A and 4B are a side view and a bottom view, respectively, showing the structure of the chamber member according to the embodiment. The chamber member 40 has spaces 41 to 44 partitioned from each other by partition walls 45 to 47. By providing the perforated plate 20 so as to cover the chamber member 40 from the −D direction side, each of the spaces 41 to 44 becomes a waveguide whose walls are formed by the chamber member 40 and the perforated plate 20. Specifically, the space 41 is covered by a perforated region 21 , a non-perforated region 31 adjacent to the perforated region 21 , and a perforated region 22 not adjacent to the perforated region 21 and adjacent to the non-perforated region 31 . Space 42 is covered by non-perforated region 32 , perforated region 23 , non-perforated region 33 and perforated region 24 . Space 43 is covered by perforated region 25 and non-perforated region 34 adjacent to perforated region 25 . The space 44 is covered by a non-perforated region 35 , a perforated region 26 , a non-perforated region 36 and a perforated region 27 .

Hereinafter, a waveguide having a space 41 will be referred to as a waveguide 11, a waveguide having a space 42 will be referred to as a waveguide 12, a waveguide having a space 43 will be referred to as a waveguide 13, and a waveguide having a space 44 will be referred to as a waveguide 13. A waveguide having the following is called a waveguide 14. The waveguide 11 and the waveguide 12 are adjacent to each other via the partition wall 45, the waveguide 12 and the waveguide 13 are adjacent to each other via the partition wall 46, and the waveguide 13 and the waveguide are adjacent to each other via the partition wall 46. 14 with a partition wall 47 in between. That is, the partition walls 45 to 47 divide the inside of the sound absorption unit 10 into a plurality of waveguides.

The partition walls 45 to 47 extend in substantially the same direction. Therefore, each of the waveguides 11 to 14 has a substantially trapezoidal outline when viewed from the -D direction, and extends substantially parallel to each other. The waveguide 11 and the waveguide 12 have different shapes and sizes, and the waveguide 13 and the waveguide 14 have different shapes and sizes. The waveguide 12 and the waveguide 13 have substantially the same cavity shape and size, but differ in the arrangement of the perforations formed in their respective walls. Although the waveguide 11 and the waveguide 14 have substantially the same cavity shape and size, the arrangement of the perforations formed in each wall is different.

Note that the sound absorption unit 10 may be configured as a whole, or may be configured by combining a plurality of members. For example, the sound absorption unit 10 may be configured by combining the perforated plate 20 and the chamber member 40, or the perforated plate 20 and the chamber member 40 may be configured integrally. Furthermore, for example, the sound absorbing unit 10 may be configured by combining members constituting each waveguide. That is, the sound absorption unit 10 only needs to have a plurality of waveguides, and a perforated region and a non-perforated region exist in the member constituting the wall of each waveguide. The inside and outside of each waveguide communicate with each other via a plurality of perforations present in the perforation area, allowing ventilation.

Specifically, the inside and outside of the waveguide 11 communicate with each other through a plurality of perforations formed in the perforation region 21 and the perforation region 22, allowing ventilation. On the other hand, in the portion covered by the non-perforated region 31, ventilation is not possible between the inside and outside of the waveguide 11. Similarly, the inside and outside of the waveguide 12 communicate with each other via a plurality of perforations formed in the perforation region 23 and the perforation region 24 . The inside and outside of the waveguide 13 communicate with each other via a plurality of perforations formed in the perforation region 25. The inside and outside of the waveguide 14 communicate with each other via a plurality of perforations formed in the perforation region 26 and the perforation region 27 .

The perforated surfaces of the perforated plates 20 forming the walls of each of the waveguides 11 to 14 are exposed when viewed from the −D direction. Sound waves arriving from the -D direction with respect to the sound absorption unit 10 and incident on the perforated plate 20 enter the inside of each waveguide through the plurality of perforations formed in the perforated area, and are covered by the non-perforated area. The light travels in a direction non-parallel to the direction D, and is reflected by the side surface of the chamber member 40. Each perforated region of the perforated plate 20 functions as an acoustic impedance matching member, and the waveguides 11 to 14 function as resonators having mutually different resonance characteristics. Therefore, according to the sound absorbing unit 10, a sound absorbing effect can be obtained in a wide frequency band compared to a sound absorbing material having a single waveguide. The sound absorption characteristics of the sound absorption unit 10 in this embodiment are expressed by, for example, sound absorption coefficient for each frequency or acoustic impedance. The sound absorption unit 10 may be designed so that the frequency bands of sound waves absorbed by each waveguide do not overlap with each other, or the sound absorption unit 10 may be designed such that the frequency bands of sound waves absorbed by each waveguide partially overlap. Unit 10 may be designed.

The volume of the waveguide 11 is smaller than the volume of the waveguide 12, and the volume of the waveguide 13 is larger than the volume of the waveguide 14. By making the sizes of the plurality of waveguides different in this way, it is possible to make the resonance characteristics of the waveguides different. Note that the distance between the perforated region 21 and the perforated region 22 on the surface of the perforated plate 20 (length L1 in FIG. It is longer than the thickness L2) in 2(b). With this configuration, in the waveguide 11, the sound absorption coefficient in the low frequency band is improved by increasing the length of the path along which the sound wave travels in a direction non-parallel to the D direction, and the D of the sound absorption unit 10 is increased. The directional depth (that is, the thickness) can be reduced. Further, the length of the non-perforated area 34 in the direction connecting the center of gravity of the perforated area 25 and the center of gravity of the non-perforated area 34 on the surface of the perforated plate 20 (length L3 in FIG. 1(b)) is is longer than the length of the waveguide 13 in the normal direction (thickness L4 in FIG. 2(b)). With this configuration, in the waveguide 13, the sound absorption coefficient in the low frequency band is improved by increasing the length of the path along which the sound wave travels in a direction non-parallel to the D direction, and the thickness of the sound absorption unit 10 is increased. can be made smaller.

Compared to the waveguide 13, the waveguide 11 has a superior sound absorption coefficient in high frequency bands. On the other hand, the waveguide 13 has a better sound absorption coefficient in a low frequency band than the waveguide 11. Here, in the portion of the perforated plate 20 that constitutes the wall of the waveguide 13, the perforations are arranged in one place (that is, perforated area 25). With such a configuration, it is possible to improve the sound absorption coefficient in a low frequency band by the waveguide 13, compared to a case where the perforations are distributed at a plurality of locations. On the other hand, in the portion of the perforated plate 20 that constitutes the wall of the waveguide 11, the perforations are arranged in a plurality of locations (that is, perforated regions 21 and 22). With such a configuration, the sound absorption coefficient in a high frequency band by the waveguide 11 can be improved compared to a case where the perforations are arranged in one place. As described below, it is possible to change the sound absorption characteristics of a waveguide by changing parameters such as the size of each perforation, but this is possible if there are manufacturing restrictions on the size of the perforations, etc. However, desired sound absorption characteristics can be achieved by appropriately designing the arrangement of perforations.

The sound absorbing unit 10 exhibits sound absorbing performance depending on its shape and structure, so it can be constructed using various materials. The sound absorption unit 10 is made of, for example, a material such as resin, metal, silicone, rubber, polymer, paper, cardboard, wood, or nonwoven fabric. However, the sound absorbing unit 10 may be made of materials other than these materials. Further, the sound absorption unit 10 may be configured by combining a plurality of members each made of different materials. For example, the perforated plate 20 and the chamber member 40 of the sound absorption unit 10 may be made of different materials.

(1-2) Configuration of perforated plate The configuration of the perforated plate 20 will be explained. A plurality of perforations are formed in each of the perforation areas 21 to 27 of the perforation plate 20. Note that the perforated plate 20 may be configured as one piece, or may be configured by combining a plurality of members. For example, the portion of the perforated plate 20 that covers each waveguide may be formed from a separate member, or each perforated area and each non-perforated area of the perforated plate 20 may be formed from a separate member. However, the perforated plate 20 may be composed of six triangular plate members. By configuring the entire perforated plate 20 as one piece, the manufacturing process of the perforated plate 20 can be simplified and manufacturing costs can be reduced. On the other hand, by configuring the perforated plate 20 by combining a plurality of members, the size of each member can be reduced, so even if there is a limit to the size of the members that can be manufactured, a large perforated plate 20 can be created.

The resonance characteristics of each waveguide depend on the shape of the waveguide and the shape parameters of the perforated plate (hereinafter referred to as "hole parameters") combined with the waveguide. Pore parameters include, for example:
・Area of the perforation area (area of the surface where the hole is formed)
・Thickness of perforated plate (dimension in the direction perpendicular to the surface)
- Size of the hole (e.g. diameter if the hole is circular)
・Percentage of the area of the holes on the surface of the perforated plate (hereinafter referred to as "hole occupancy")
- Shape of holes, number of holes, spacing between holes

By changing the hole parameters of the perforated plate, the acoustic impedance of the sound absorption unit 10 can be adjusted. Additionally, the perforated plate has the effect of lowering the Q value due to thermoviscous resistance and enabling sound absorption in a wide frequency band. As a specific parameter example, it is assumed that the length of the sound absorbing unit 10 in the H direction and the W direction is respectively 10 cm to 50 cm, and the thickness of the sound absorbing unit 10 in the D direction is 2 cm to 10 cm. Further, when the thickness of the perforated plate 20 is 0.5 mm to 3 mm, the diameter of the hole existing in the perforated plate is set to 0.3 mm to 3 mm. By appropriately setting other parameters such as the number of holes in the perforated plate, it is possible to efficiently absorb (reduce sound pressure) the sounds in the range of 400Hz to 1500Hz, which is the main component of the sounds contained in human conversation. be able to. In this case, the average sound absorption coefficient of sounds in the range of 400 Hz to 1500 Hz by the sound absorption unit 10 is higher than the average sound absorption coefficient of sounds in other frequency bands (frequency bands lower than 400 Hz and frequency bands higher than 1500 Hz) by the sound absorption unit 10. . Moreover, the sound absorption characteristics of the sound absorption unit 10 can be changed by adjusting at least one of the shape of the waveguide and the hole parameters. For example, the sound absorption unit 10 can be designed so that the average sound absorption coefficient for sounds in the range of 1000 Hz to 4000 Hz is higher than the average sound absorption coefficient for sounds in other frequency bands. For example, the sound absorption unit 10 can also be designed to efficiently absorb sounds of 200 Hz or more and 2500 Hz or less.

The hole parameters of the plurality of perforation regions included in the sound absorption unit 10 may be different from each other. For example, the hole parameters of the perforated region 21 and the perforated region 22 may be optimized depending on the sound absorption properties required of the waveguide 11. The hole parameters of the perforated region 23 and the perforated region 24 may be optimized depending on the sound absorption properties required of the waveguide 12. The hole parameters of the perforated region 25 may be optimized depending on the sound absorption properties required of the waveguide 13. The hole parameters of the perforated region 26 and the perforated region 27 may be optimized depending on the sound absorption properties required of the waveguide 14. That is, a hole that communicates the inside and outside of one of the waveguides 11 to 14 and a hole that connects the inside and outside of the other waveguide are determined by at least one of the hole parameters or The arrangement of the holes may be different. Thereby, the sound absorption unit 10 can achieve a high sound absorption coefficient in a wide frequency band. However, the present invention is not limited to this, and the hole parameters of the plurality of perforation regions included in the sound absorption unit 10 may be common. Thereby, the specifications of the holes in the perforated plate 20 can be unified, so that the manufacturing cost of the perforated plate 20 can be reduced.

Note that in the example of the sound absorption unit 10, the surface of the perforated plate 20 is planar, but the shape of the perforated plate 20 is not limited to this. For example, the surface of the perforated plate 20 may be a curved surface or may have irregularities.

(2) How to use the sound absorption unit How to use the sound absorption unit will be explained. FIG. 5 is a diagram illustrating the functions of the sound absorption unit according to the embodiment. As shown in FIG. 5, the sound absorption unit 10 is installed at a position away from the noise source NS that emits the sound to be absorbed in the D direction. Each waveguide included in the sound absorption unit 10 absorbs a frequency of sound waves traveling in the D direction from the noise source NS according to the shape (for example, length or volume) of the waveguide and the hole parameters of the perforated plate. absorb ingredients. Thereby, the sound pressure of the sound wave reaching the position on the D direction side from the sound absorption unit 10 from the noise source NS is significantly reduced compared to the case where the sound absorption unit 10 is not installed.

FIG. 6 is a diagram showing an example of use of the sound absorption unit according to the embodiment. As shown in FIG. 6, by installing a plurality of sound absorption units 10 in combination, the sound pressure of the sound emitted from the noise source NS can be further reduced. The plurality of sound absorbing units 10 are installed in combination so as to constitute a sound absorbing wall 1 that blocks sound waves traveling from the noise source NS in the direction of the human HMa. Specifically, the plurality of sound absorbing units 10 are attached to the support plate 50 so that the surface of the perforated plate 20 (the surface on which the perforations are formed) of each of the plurality of sound absorbing units 10 is exposed when viewed from the same direction. , the sound absorbing wall 1 is constructed. Since the sound absorption wall 1 has a sound insulation effect, by installing the sound absorption wall 1, the sound pressure of the sound wave emitted from the noise source NS is greatly reduced when passing through the sound absorption wall 1, and the sound absorption is reduced as seen from the noise source NS. The noise felt by the person HMa who is located deeper than the wall 1 can be reduced.

In addition, since the sound absorption wall 1 has a sound absorption effect, by installing the sound absorption wall 1, the amount of sound reflected by the wall will be lower than when a wall made of conventional members (for example, a concrete wall) is installed at the same position. The volume of the sound decreases. Therefore, the sound pressure of the sound waves emitted from the noise source NS is greatly reduced when reflected by the sound absorption wall 1, reducing the noise felt by the person HMb who is on the opposite side of the sound absorption wall 1 with respect to the noise source NS. can do. Furthermore, when the sound absorbing wall 1 is installed, the volume of sound that goes around to the back of the wall due to diffraction is also reduced compared to when a wall made of conventional members is installed at the same position. This effect makes it possible to further reduce the noise felt by the person HMa who is behind the wall.

Although the use of the sound absorption wall 1 is not limited, for example, the sound absorption wall 1 can be used in the following applications. The sound-absorbing wall 1 can suppress noise generated by automobiles or trains by being placed around roads or railroad tracks. The sound-absorbing wall 1 can suppress construction noise by being placed at a construction site. By being used as a wall of a building, the sound absorbing wall 1 can suppress noise within the building. The sound-absorbing wall 1 is placed around a person's work place (for example, a work desk) to suppress noise perceived by the worker and to suppress leakage of noise emitted by the worker to the surroundings. be able to. As for how to place the sound absorbing wall 1 around the work place, the sound absorbing wall 1 may be placed so as to surround the work place on all four sides, or the sound absorbing wall 1 may be placed so as to surround the work place in three directions excluding the direction of the entrance/exit. Alternatively, only one sound absorbing wall 1 may be placed. Further, a work booth may be configured by blocking the ceiling of a work place surrounded by sound-absorbing walls 1 on all sides.

In this embodiment, the perforated plate 20 and the chamber member 40 are each made of a light-transmitting material. As the light-transmitting material, for example, resin materials such as glass and acrylic can be used, but the material is not limited thereto. Note that the sound absorbing unit 10 only needs to have at least the outer shell having light transmittance. That is, the portions of the chamber member 40 other than the partition walls 45 to 47 and the perforated plate 20 are made of a transparent or translucent material. The sound absorbing unit 10 having such a configuration is a sound absorbing member suitable for use on a wall surface having light transmittance such as glass or acrylic.

For example, consider a case where a glass screen or low partition is used as the support plate 50 in FIG. 6. When the sound absorption unit 10 is not attached to the support plate 50, the support plate 50 has optical transparency, so the human HMa passes through the support plate 50 and is visually recognized by the human HMb. On the other hand, if a sound absorbing material that does not have optical transparency is attached to the support plate 50, the human HMb will not be able to visually recognize the human HMa. That is, the functionality and design of the support plate 50 are impaired by the attachment of the sound absorbing material. On the other hand, when the light-transmitting sound absorbing unit 10 is attached to the support plate 50, the human HMb can visually recognize the human HMa, and the functionality and design of the support plate 50 are maintained.

Note that by attaching the translucent sound absorbing unit 10 to a wall surface, it is also possible to change the transparency of the wall surface to which it is attached. For example, if a sound absorption unit is not attached to the support plate 50 made of glass, the humans HMa and HMb who are on opposite sides of the support plate 50 can visually recognize each other's actions. On the other hand, when the translucent sound absorption unit 10 is attached to the support plate 50, the transparency of the sound absorption wall 1 made up of the sound absorption unit 10 and the support plate 50 is lower than that of the support plate 50. As a result, human HMa and human HMb can visually recognize each other's presence, but cannot visually recognize the detailed contents of their actions. According to such a configuration, privacy can be protected between people who are on opposite sides of the support plate 50. Note that the translucent sound absorption unit 10 can be realized by using a translucent material for the perforated plate 20 or by increasing the surface roughness of the perforated plate 20.

Furthermore, the sound absorbing unit 10 can also be used on a wall surface that does not have light transmittance. For example, consider a case where a screen that is opaque and has a characteristic pattern on its surface is used as the support plate 50 in FIG. In this case, if a sound absorbing material that does not have light transmittance is attached to the support plate 50, the characteristic pattern will not be visible and the design will be impaired. When installed, the distinctive pattern becomes visible and the design is maintained.

Note that in FIGS. 1(a) and 1(b), the perforated plate 20 is depicted as opaque in order to simplify the drawings. However, since the perforated plate 20 is actually transparent or semi-transparent, when viewed from the same angles as in these figures (oblique direction and -D direction), the partition walls 45 to 47 do not pass through the perforated plate 20. Visible. Furthermore, the partition walls 45 to 47 may be made of a light-transmitting material. Thereby, visibility through the sound absorption unit 10 can be further improved.

FIG. 7 is a diagram showing another usage example of the sound absorption unit according to the embodiment. As shown in FIG. 7, by attaching a plurality of sound absorption units 10 to the wall surface 60 of the space SP, the sound pressure in the space SP can be reduced. Specifically, a sound-absorbing panel is constructed by adding a mounting structure to the sound-absorbing unit 10 that allows the sound-absorbing unit 10 to be attached to the wall surface 60. Then, a plurality of sound absorbing panels are attached to the wall surface 60 side by side so that the surface of the perforated plate 20 (the surface on which the perforations are formed) of each of the plurality of sound absorbing units 10 is exposed when viewed from the normal direction of the wall surface 60. Since the sound absorbing panel has the mounting structure, the sound absorbing unit 10 can be easily attached to or removed from the wall surface 60. As the mounting structure, for example, double-sided tape, screw fixing tool, magnet, hook-and-loop fastener, or suction cup can be used.

If the sound absorption unit 10 is not installed in the space SP, the sound of the conversation between the human HMc and the human HMd in the space SP will echo within the space SP, and will interfere with the conversation between the human HMe and the human HMf who are in the same space SP. Sometimes it happens. On the other hand, by attaching the sound absorbing unit 10 to the wall surface 60, the sound incident on the wall surface 60 is absorbed, and the echo of the sound in the space SP can be suppressed. Further, it is also possible to suppress sound leaking from inside the space SP to the outside of the space SP. Furthermore, by designing the shape of the waveguide and the hole parameters of the perforated plate 20 so that the sound absorption unit 10 has desired sound absorption characteristics, the sound of a specific frequency band in the space SP can be made more efficient than the sound of other frequency bands. It can be significantly reduced. Thereby, the resonance of the sound in the space SP can be adjusted.

As described above, at least the outer shell of the sound absorbing unit 10 is transparent to light. Therefore, for example, when the wall surface 60 is made of a light-transmitting material such as glass, it is possible to particularly prevent the functionality and design of the space SP from being impaired. Furthermore, the mounting structure for mounting the sound absorbing unit 10 on the wall surface 60 may be made of a light-transmitting material. Moreover, regardless of whether the mounting structure has optical transparency, the mounting structure may not be provided on the entire surface of the mounting surface of the sound absorption unit 10, but may be provided only on a part of the mounting surface. These configurations can further prevent the functionality and design of the space SP from being impaired.

(3) Method of designing sound absorption unit (3-1) Configuration of design device The configuration of the design device that executes processing for designing the sound absorption unit 10 will be described. FIG. 8 is a diagram showing an example of the configuration of the design device. As shown in FIG. 8, the design device 210 includes a storage device 211, a processor 212, an input/output interface 213, and a communication interface 214.

The storage device 211 is configured to store programs and data. The storage device 211 is, for example, a combination of ROM (Read Only Memory), RAM (Random Access Memory), and storage (for example, flash memory or hard disk). The programs include, for example, an OS (Operating System) program and an application program (for example, a web browser) that executes information processing. The data includes, for example, data and databases referred to in information processing, and data obtained by executing information processing (that is, execution results of information processing). The programs and data stored in the storage device 211 may be provided via a network, or may be provided by being recorded on a computer-readable recording medium.

The processor 212 implements the functions of the design device 210 by executing programs stored in the storage device 211 and processing data. Note that at least part of the functions of the design device 210 may be realized by dedicated hardware (for example, an ASIC (application specific integrated circuit) or an FPGA (field-programmable gate array)).

The input/output interface 213 has a function of receiving input according to a user operation on an input device connected to the design apparatus 210 and a function of outputting information to an output device connected to the design apparatus 210. The input device is, for example, a keyboard, pointing device, touch panel, or a combination thereof. The output device is, for example, a display that displays images or a speaker that outputs audio. Communication interface 214 controls communication between design device 210 and an external device (eg, a server).

(3-2) Design Processing Processing for designing the sound absorption unit 10 will be explained. FIG. 9 is a diagram showing the design process of the sound absorption unit by the design device.

The processing shown in FIG. 6 is realized by the processor 212 of the design device 210 executing a program stored in the storage device 211. However, at least a part of the processing shown in FIG. 6 may be realized by dedicated hardware. The process shown in FIG. 6 is started in response to a user inputting an instruction to the design device 210 to start designing the sound absorption unit 10. However, the starting conditions for the process shown in FIG. 6 are not limited to this.

In S100, the design device 210 acquires fixed values that can be set as design parameters of the sound absorption unit 10. For example, the processor 212 obtains the fixed value by accepting user input or by reading a file in which the fixed value is stored. The design parameters of the sound absorption unit 10 include, for example, at least one of the following.
・Size of sound absorption unit 10 (dimensions in H direction, D direction, and W direction)
・Number of waveguides ・Length or volume of waveguide (dimensions in H direction or W direction)
・Waveguide depth (D dimension)
- Shape of the waveguide - Shape of the side wall included in the sound absorption unit 10 - Hole parameters of the perforated plate

As an example, in the following description, it is assumed that the size of the sound absorption unit 10, the number of waveguides, and the shape of the side wall are acquired as fixed values in S100. It is assumed that the hole parameters of the perforated plate, the size of the waveguide, and the shape of the waveguide are treated as variables.

In S101, the design device 210 acquires the domain (possible range of the variable) of the design parameter treated as a variable. For example, the processor 212 obtains the domain of the variable by accepting user input or by reading a file in which the domain of the variable is stored.

In S102, the design device 210 constructs an analytical model of the sound absorption unit 10. Specifically, the processor 212 uses the fixed value acquired in S100 and the value of the variable selected from the domain acquired in S101 as design parameters of the analytical model of the sound absorption unit 10.

In S103, the design device 210 evaluates the sound absorption characteristics of the analytical model. Specifically, the processor 212 acquires the evaluation value of the sound absorption characteristics of the analytical model by analyzing the sound absorption characteristics through acoustic simulation using the analytical model constructed in S102. For example, the design device 210 obtains the average sound absorption coefficient or average reflection coefficient in each of a plurality of frequency bands. Note that the method for evaluating sound absorption characteristics is not limited to this. For example, the design device 210 may obtain the average transmittance in each of a plurality of frequency bands.

In S104, the design device 210 determines the search state. Specifically, the processor 212 determines whether the domain obtained in S101 has been searched for each variable (that is, whether the analysis model has been constructed using all selectable values from the domain and the sound absorption characteristics have been evaluated). Determine whether the process has ended (or not).

If it is determined that the search is not completed in S104, the process returns to S102, and the design device 210 selects new variable values from the domain obtained in S101, and executes the construction of the analytical model and the evaluation of the sound absorption characteristics again. On the other hand, if it is determined in S104 that the search has ended, the process advances to S105.

In S105, the design device 210 extracts optimal values of variables. Specifically, the processor 212 extracts, as the optimal value, the numerical value of the design parameter corresponding to the analytical model that showed the highest evaluation value in the repeatedly executed sound absorption characteristic evaluation in S103. For example, if 400 Hz to 1000 Hz is specified as the frequency band for sound absorption, the numerical value of the design parameter of the analytical model with the highest average sound absorption coefficient for 400 Hz to 1000 Hz is extracted as the optimum value. By designing the sound absorbing unit 10 using the optimum values extracted in this way, it is possible to manufacture the sound absorbing unit 10 with excellent sound absorbing characteristics in the range of 400 Hz to 1000 Hz. The frequency band to be subjected to sound absorption may be specified according to user input.

After S105, the processing flow in FIG. 6 ends. In addition, in the process flow of FIG. 6, the processes of S100 and S101 may be performed in the reverse order or may be performed in parallel. Further, the design device 210 may output information indicating the evaluation result of the analytical model instead of extracting the optimum value of the variable in S105, or in addition to the process in S105. For example, the design device 210 may output information indicating the sound absorption characteristics of each of the plurality of analytical models constructed in S102, or output information indicating the sound absorption characteristics of the analytical model corresponding to the optimal value extracted in S105. You may. The information output by the design device 210 may be a numerical value indicating sound absorption characteristics, or may be an image output to a display device.

Note that in the above description, a case has been described in which the sound absorption unit 10 is designed so that the sound absorption performance in a predetermined frequency band is the highest. However, the present invention is not limited to this, and the sound absorption unit 10 may be designed so that a specified sound absorption performance is achieved in a predetermined frequency band. For example, you may want to suppress the echo of a person's voice in a space, but leave some echo so that the voice can be heard naturally. In this case, in S105, the design device 210 extracts the numerical value of the design parameter of the analytical model whose average sound absorption coefficient in the specified frequency band of 400 Hz to 1000 Hz is closest to the specified value (for example, 0.5) as the optimal value. . Further, for example, there may be a case where it is desired to suppress the reverberations of bass sounds in a space, but to leave the reverberations of high sounds. In this case, in S105, the design device 210 optimizes the numerical values of the design parameters of the analytical model in which the average sound absorption coefficient of 100Hz to 500Hz is higher than the average sound absorption coefficient of 800Hz to 2000Hz, and the difference between these average sound absorption coefficients is the largest. It may be extracted as a value.

(4) Modification example (4-1) Modification example 1 of sound absorption unit
A modification of the structure of the sound absorption unit will be described. The sound absorption unit 10 described in the embodiment described above can be replaced with a sound absorption unit of a modified example described below. FIGS. 10(a) and 10(b) are a perspective view and a front view, respectively, showing the structure of a sound absorption unit according to a modification. FIGS. 11(a) and 11(b) are a side view and a bottom view, respectively, showing the structure of a sound absorbing unit according to a modification. FIGS. 12(a) and 12(b) are a perspective view and a front view, respectively, showing the structure of a chamber member according to a modified example. 13(a) and 13(b) are a side view and a bottom view, respectively, showing the structure of a chamber member according to a modified example. In the sound absorption unit 10 described using FIGS. 1 to 4, the plurality of partition walls extend in substantially the same direction, so that the plurality of waveguides are arranged substantially in parallel. On the other hand, in the sound absorption unit 110 described using FIGS. 10 to 13, a plurality of partition walls that divide the inside of the sound absorption unit 110 into a plurality of waveguides are respectively located inside the sound absorption unit 110 when viewed from the -D direction. It extends from the position toward the periphery of the sound absorption unit 110.

As shown in FIG. 10, the sound absorption unit 110 includes a perforated plate 120, which is a plate-like member with perforations formed therein, and a chamber member 140, which forms a cavity when combined with the perforated plate 120. On the surface of the perforated plate 120, there are a plurality of perforated areas each having a plurality of perforations formed therein, and a plurality of non-perforated areas having no perforations formed therein. The sound absorbing unit 110 has a polygonal (specifically hexagonal) shape when viewed from the −D direction.

As shown in FIG. 12, the chamber member 140 has spaces 141 to 146 partitioned from each other by partition walls 147 to 152. By providing the perforated plate 120 to cover the chamber member 140 from the -D direction side, each of the spaces 141 to 146 becomes a waveguide whose walls are formed by the chamber member 140 and the perforated plate 120. Specifically, the space 141 is covered by the perforated region 121 and the non-perforated region 131 adjacent to the perforated region 21 . Space 142 is covered by perforated region 122 and non-perforated region 132. Space 143 is covered by perforated region 123 and non-perforated region 133. Space 144 is covered by perforated region 124 and non-perforated region 134 . Space 145 is covered by perforated region 125 and non-perforated region 135. Space 146 is covered by perforated region 126 and non-perforated region 136.

Hereinafter, waveguides having spaces 141 to 146 will be referred to as waveguides 111 to 116, respectively. The partition walls 147 to 152 divide the inside of the sound absorption unit 110 into a plurality of waveguides, and each waveguide is adjacent to two other waveguides via the partition wall. The partition walls 147 to 152 extend from a position 153 toward each apex of the hexagon when viewed from the −D direction, and the waveguides 111 to 116 each have a triangular shape when viewed from the −D direction. Since the position 153 is shifted from the center of the sound absorption unit 110 when viewed from the −D direction, the waveguide 111, the waveguide 116, and the waveguide 115 have different shapes and sizes, and the waveguide 112, the waveguide The wave tube 113 and the waveguide 114 have mutually different shapes and sizes. The waveguide 12 and the waveguide 13 have substantially the same cavity shape and size, but differ in the arrangement of the perforations formed in their respective walls. The waveguide 111 and the waveguide 112, the waveguide 116 and the waveguide 113, and the waveguide 114 and the waveguide 115 each have cavities of approximately the same size, but are formed in their respective walls. The arrangement of the perforations is different.

The perforated surface of the perforated plate 120 forming the wall of each of the waveguides 111 to 116 is exposed when viewed from the -D direction. A sound wave that comes from the -D direction with respect to the sound absorption unit 110 and enters the perforated plate 120 enters the inside of each waveguide through the plurality of perforations formed in the perforated area, and is covered by the non-perforated area. The light travels in a direction non-parallel to the direction D, and is reflected by the side surface of the chamber member 140. Each perforated region of the perforated plate 120 functions as an acoustic impedance matching member, and the waveguides 111 to 116 function as resonators having mutually different resonance characteristics. Therefore, according to the sound absorbing unit 110, a sound absorbing effect can be obtained in a wide frequency band compared to a sound absorbing material having a single waveguide.

For example, the waveguide 113 has a better sound absorption coefficient in a low frequency band than the waveguide 112, and the waveguide 114 has a better sound absorption coefficient in a lower frequency band than the waveguide 113. Further, the waveguide 116 has a better sound absorption coefficient in a low frequency band than the waveguide 111, and the waveguide 115 has a better sound absorption coefficient in a lower frequency band than the waveguide 116. Note that the sound absorption unit 110 may be designed so that the frequency bands of sound waves absorbed by each waveguide do not overlap with each other, or the sound absorption unit 110 may be designed such that the frequency bands of sound waves absorbed by each waveguide partially overlap. Unit 110 may be designed.

The length of the non-perforated region 135 in the direction connecting the center of gravity of the perforated region 125 and the center of gravity of the non-perforated region 135 (length L5 in FIG. 10(b)) is the length of the waveguide in the normal direction of the surface of the perforated plate 120. 115 (thickness L6 in FIG. 11(b)). With this configuration, in the waveguide 115, the sound absorption coefficient in the low frequency band is improved by increasing the length of the path along which the sound wave travels in a direction non-parallel to the D direction. The directional depth (that is, the thickness) can be reduced.

Note that the arrangement of the perforations in the sound absorption unit 110 is not limited to the example shown in FIG. 10. FIG. 14 shows a modification of the structure of the perforated plate in the sound absorption unit 110. The perforated plate 220 in FIG. 14 is newly provided with a perforated area 221 and a perforated area 222 compared to the perforated plate 120 in FIG. 10 . That is, in the portion of the perforated plate 220 that constitutes the wall of the waveguide 115, the perforations are arranged at multiple locations. With such a configuration, the sound absorption coefficient in a high frequency band by the waveguide 111 can be improved compared to the case where the perforations are arranged in one place (that is, when the perforated plate 120 is used). Note that the distance between the perforated region 125 and the perforated region 221 on the surface of the perforated plate 220 (length L7 in FIG. 14) is the length of the waveguide 111 in the normal direction of the surface of the perforated plate 220 (FIG. ) equal to the thickness L6 at ). With this configuration, in the waveguide 115, the sound absorption coefficient in the low frequency band is improved by increasing the length of the path along which the sound wave travels in a direction non-parallel to the D direction, and the thickness of the sound absorption unit 110 is increased. can be made smaller.

Note that in FIGS. 10(a) and 10(b), the perforated plate 120 is depicted as opaque in order to simplify the drawings. However, since the perforated plate 120 is actually transparent or semi-transparent, when viewed from the same angle as in these figures (oblique direction and -D direction), the partition walls 147 to 152 do not pass through the perforated plate 120. Visible. Further, the partition walls 147 to 152 may be made of a light-transmitting material. Thereby, visibility through the sound absorption unit 110 can be further improved.

(4-2) Other variations

In the embodiments described above, the sound absorption unit has a combination of a plurality of waveguides having different shapes and sizes, and a combination of a plurality of waveguides having substantially the same shape and size. However, the present invention is not limited thereto, and the sound absorbing unit may just have a cavity surrounded by an outer shell and a perforation that communicates the inside of the cavity with the outside. That is, the sound absorbing unit only needs to have at least one space in which air resonates, and it is not essential that the sound absorbing unit has a partition wall that divides the internal space. Further, the number of cavities and the number of perforations that the sound absorbing unit has may be one or more. However, if the sound absorbing unit has a plurality of cavities (waveguides) having at least one different shape and size, it is possible to absorb sound in a wider frequency band. Furthermore, by forming a plurality of perforations in one cavity, it is possible to reduce the deviation in the sound absorption coefficient depending on the frequency (that is, to make the peak of the sound absorption characteristic gentle). Further, in the above-described embodiment, the perforations of the plurality of waveguides included in the sound absorption unit are arranged differently from each other, but the present invention is not limited to this. It may be By providing the sound absorption unit with two or more waveguides having mutually different resonance characteristics, it is possible to absorb sound in a wide frequency band. On the other hand, some of the plurality of waveguides included in the sound absorption unit have resonance characteristics that are close to each other, so that the sound absorption coefficient in a specific frequency band can be improved.

In the embodiment described above, the length of the waveguide in the normal direction to the surface of the perforated plate is non-uniform. For example, the thickness of the sound absorbing unit 10 in the D direction is thicker at the center when viewed from the −D direction than at the peripheral portion when viewed from the −D direction. According to such a configuration, the volume of each waveguide can be made larger than when the thickness of the sound absorption unit 10 is made equal to the thickness of the peripheral edge seen from the -D direction, and as a result, the volume of the waveguide can be increased. Sound absorption performance in frequency bands can be improved. However, the present invention is not limited to this, and the thickness of the sound absorbing unit 10 in the D direction may be uniform. In this case, the length of the waveguide in the normal direction to the surface of the perforated plate also becomes uniform.

In the sound absorption unit according to the above-described embodiment, a cavity (waveguide) is formed by the perforated plate and the base body (chamber member) that is integrally fixed to the perforated plate. Note that the perforated plate provided in the sound absorption unit may be configured to be detachable from the chamber member. Thereby, even if the perforated plate is worn out and the sound absorption characteristics of the sound absorption unit deteriorate, the perforated plate can be easily replaced and the sound absorption characteristics of the sound absorption unit can be improved. Furthermore, by replacing the perforated plate with another perforated plate having different hole parameters, the sound absorption characteristics of the sound absorption unit can be adjusted as desired. In addition, when the perforated plate and the chamber member are separable, the partition wall that divides the internal space of the sound absorption unit may be provided on the chamber member or the perforated plate, or the perforated plate may be provided on both the chamber member and the perforated plate. It may also be a member independent of the plate.

At least one of the perforated plate and the partition wall provided in the sound absorption unit may be configured to be movable. Moreover, a new member may be added inside the waveguide. Thereby, the shape and size of the waveguide can be easily adjusted, and the sound absorption characteristics of the sound absorption unit can be adjusted as desired.

In the above embodiment and each modification, the sound absorption unit has a hexagonal shape when viewed from the -D direction, a perforated surface is provided on the surface of the sound absorption unit on the -D direction side, and the inside of the sound absorption unit is surrounded by a partition wall. Divided into multiple cavities. However, the shape of the sound absorbing unit may be other polyhedrons or spheres. Further, the perforated surface may be provided on another surface of the sound absorption unit. Moreover, a structure other than a cavity may be included inside the sound absorption unit.

As explained using FIGS. 6 and 7, by arranging a plurality of sound absorption units side by side, sound can be absorbed over a wide range. At this time, a plurality of sound absorbing units having the same shape may be arranged side by side, or a plurality of sound absorbing units having different shapes may be arranged side by side. For example, the plurality of types of sound absorbing units described in the above embodiment and each modification may be arranged side by side. Further, for example, a plurality of sound absorption units having the same waveguide shape but different hole parameters of the perforated plate may be arranged side by side. By arranging a plurality of sound absorption units with different sound absorption characteristics side by side, it is possible to obtain a sound absorption effect in a wider frequency band than when arranging the same sound absorption units side by side. On the other hand, when the same sound absorption units are arranged side by side, a higher sound absorption effect can be obtained in a specific frequency band than when a plurality of sound absorption units having different sound absorption characteristics are arranged side by side.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the above embodiments. Moreover, various improvements and changes can be made to the embodiments described above without departing from the spirit of the present invention. Furthermore, the above embodiments and modifications may be combined.

1: Sound absorption wall 10: Sound absorption unit 20: Perforated plate

Claims

a cavity surrounded by a light-transmitting outer shell;
a perforation that communicates the inside and outside of the cavity;
A sound absorbing member having.
The hollow portion is formed by a perforated plate in which the perforated hole is formed, and a base body that is integrally fixed to the perforated plate,
Both the perforated plate and the base body have optical transparency;
The sound absorbing member according to claim 1.
The sound absorbing member according to claim 1, wherein the space contained in the outer shell is divided into a plurality of the hollow parts by partition walls.
The sound absorbing member according to claim 3, wherein the plurality of cavity portions function as resonators having mutually different resonance characteristics.
The sound absorbing member according to any one of claims 1 to 4,
Mounting means that allows the sound absorbing member to be mounted on a wall surface;
Sound absorbing panel with.
The sound absorbing panel according to claim 5, wherein the mounting means has optical transparency.
A wall surface having light transparency;
The sound absorbing member according to any one of claims 1 to 4 attached to the wall surface,
Sound absorbing wall with.
A plurality of the sound absorbing members are attached to the wall surface,
The surface of each of the plurality of sound absorbing members on which the perforations are formed is exposed when viewed from a predetermined direction;
The sound absorbing wall according to claim 7.