Sound absorption structure and anechoic chamber

Abstract

The utility model provides a sound absorption structure. The sound absorption structure is sequentially provided with a sound absorption assembly, a first micro-perforated plate assembly is arranged on the surface of the sound wave emitting side of the sound absorption assembly, and the first micro-perforated plate assembly is provided with one or more first micro-perforated plates; the surface of the sound wave incidence side of the sound absorption wedge is provided with at least one second micro-perforated plate opposite to at least one first micro-perforated plate in the first micro-perforated plate assembly, and the surface of the sound wave emergence side of the sound absorption wedge is provided with a bottom plate opposite to the second micro-perforated plate; wherein a first cavity is formed between the first micro-perforated plate and the second micro-perforated plate opposite to the first micro-perforated plate, a second cavity is formed between the second micro-perforated plate and the bottom plate opposite to the second micro-perforated plate, and a first sound absorption material is arranged in the second cavity. The sound absorption structure can realize full-band efficient sound absorption, saves the space occupation of the micro-perforated plate, and reduces the overall size of the sound absorption structure.

Description

Technical Field

[0001] The utility model relates to the technical field of sound absorption, in particular to a sound absorption structure and a anechoic chamber. Background Art

[0002] With the advancement of science and technology, people's demand for the acoustic performance of high-tech products and quiet homes is increasing. Anechoic chambers are specialized laboratories used for acoustic experiments. They are widely used in various industries, including automotive, home appliances, electromechanical, and electroacoustics, for measuring noise and testing the acoustic properties of products. Acoustic wedges, the most commonly used sound-absorbing material in anechoic chambers, have a high sound absorption coefficient and can create a free-field space indoors, ensuring the accuracy of acoustic measurements.

[0003] A sound-absorbing wedge typically consists of a tip and a base. The overall sound wave incident surface is a perforated plate, and the inner cavity behind the plate is usually filled with porous sound-absorbing materials such as fiberglass, mineral wool, and foam plastic. Once the sound wave reaches the tip, the impedance matching between the tip and base allows the sound wave to enter the sound-absorbing material and be efficiently absorbed. The total length of a traditional wedge is approximately one-quarter of its cutoff frequency. For example, at a cutoff frequency of 100 Hz and a known sound velocity c of 340 m / s, the total length of a traditional wedge must reach 850 mm. Excessively long wedges significantly increase the difficulty of manufacturing and on-site installation. Furthermore, their weight increases with their size, increasing the structural load on the wall where they are installed. Furthermore, to ensure sound absorption performance at low and mid-range frequencies, the tip-to-base length ratio of a traditional wedge must be maintained at 4:1. This results in a fixed cutoff frequency, limiting the design space and flexibility. Utility Model Content

[0004] Based on this, the present invention aims to provide an improved sound absorbing structure to solve at least one of the above problems.

[0005] In a first aspect, the present application provides a sound absorbing structure, which is provided with:

[0006] A sound absorbing component, wherein a first micro-perforated plate component is provided on a surface of the sound wave exit side of the sound absorbing component, wherein the first micro-perforated plate component has one or more first micro-perforated plates; and

[0007] at least one sound absorbing wedge, wherein a surface on the sound wave incident side of the sound absorbing wedge is provided with at least one second microperforated plate opposite to the at least one first microperforated plate in the first microperforated plate assembly, and a surface on the sound wave exit side of the sound absorbing wedge is provided with a bottom plate opposite to the second microperforated plate;

[0008] A first cavity is formed between the first micro-perforated plate and the second micro-perforated plate opposite thereto, a second cavity is formed between the second micro-perforated plate and the bottom plate opposite thereto, and a first sound absorbing material is provided in the second cavity.

[0009] The above-mentioned sound absorbing structure has at least the following beneficial effects:

[0010] 1. By introducing at least two micro-perforated plates, efficient absorption of low- and medium-frequency sound waves is achieved. Furthermore, the sound-absorbing wedge can be shortened for high- and medium-frequency sound waves. This ensures impedance matching from the tip to the bottom, achieving efficient absorption of high- and medium-frequency sound waves, while reducing the height of the sound-absorbing wedge. This reduces the overall size of the sound-absorbing structure, facilitating its manufacture, transportation, storage, and wall installation.

[0011] 2. The double-layer micro-perforated plate sound absorption structure is formed by combining the micro-perforated plate on the sound-absorbing wedge with the micro-perforated plate in the sound-absorbing assembly, which can further save the space occupied by the micro-perforated plate and reduce the overall size of the sound-absorbing structure;

[0012] 3. Compared with traditional sound-absorbing wedges at the same cutoff frequency, the space occupancy rate of the above-mentioned sound-absorbing structure is significantly reduced, thereby obtaining a larger free field range when applied to the anechoic chamber, which is beneficial for various acoustic work and acoustic experiments;

[0013] 4. The above-mentioned sound-absorbing structure is significantly smaller in volume than the traditional sound-absorbing wedge, which helps to reduce the use of materials, reduce the preparation cost, and more easily meet the lightweight requirements, which helps to reduce the difficulty of construction;

[0014] 5. The structural parameters of the above-mentioned sound absorption structure can also be adjusted according to the target sound absorption frequency band. Therefore, the above-mentioned sound absorption structure also has strong frequency design adjustability, which is conducive to meeting different customized sound absorption needs.

[0015] In one embodiment, the sound absorbing assembly includes a plurality of sound absorbing units arranged in a reference plane perpendicular to the propagation direction of the sound wave, and a first micro-perforated plate is provided on the surface of the sound absorbing unit on the sound wave exit side; the sound absorbing structure includes a plurality of sound absorbing wedges arranged in a plane parallel to the reference plane, the sound absorbing wedges are arranged in a one-to-one correspondence with the sound absorbing units, and at least one second micro-perforated plate opposite to the first micro-perforated plate is provided on the surface of the sound absorbing wedge on the sound wave incident side.

[0016] In one embodiment, the sound-absorbing wedge is sequentially arranged along the propagation direction of the sound wave: a tip, whose surface on the sound wave incident side is provided with at least one of the second micro-perforated plates; a base, connected to the tip, whose surface on the sound wave exit side is provided with the bottom plate; wherein the ratio of the height of the tip to the height of the base is less than 4; or, the ratio of the height of the tip to the height of the base is less than or equal to 2.

[0017] In one embodiment, the surface of the tip portion on the sound wave incident side includes a first surface and a second surface arranged at an angle, and both the first surface and the second surface are provided with the second micro-perforated plate.

[0018] In one embodiment, the vertical distance between the center of the second micro-perforated plate and the first micro-perforated plate is the equivalent cavity depth D1 of the first cavity, and the vertical distance between the center of the second micro-perforated plate and the bottom plate is the equivalent cavity depth D2 of the second cavity, where D1 / D2 is 1 / 2.

[0019] In one embodiment, at least one layer of non-woven fabric is disposed between the first sound absorbing material and the second micro-perforated plate.

[0020] In one embodiment, the sound absorbing assembly includes one or more sound absorbing units, wherein the sound absorbing unit is sequentially provided with a perforated plate and the first micro-perforated plate along the propagation direction of the sound wave, wherein a third cavity is formed between the perforated plate and the first micro-perforated plate, and a second sound absorbing material is provided in the third cavity.

[0021] In one embodiment, at least one layer of non-woven fabric is disposed between the second sound absorbing material and the first micro-perforated plate.

[0022] In one embodiment, the sound absorbing structure further comprises a shell for accommodating the sound absorbing assembly and the at least one sound absorbing wedge, and at least one surface of the shell is a flat surface or a curved surface.

[0023] In a second aspect, the present application provides a sound absorbing structure comprising: a first sound absorbing module comprising a first sound absorbing element; a second sound absorbing module comprising a second sound absorbing element disposed opposite the first sound absorbing element and combined with the first sound absorbing element to form a third sound absorbing module; and an intrinsic sound absorbing element disposed on a side of the second sound absorbing element away from the first sound absorbing element; wherein the intrinsic sound absorbing element has intrinsic sound absorption parameters configured to absorb sound waves in a first frequency band; and the third sound absorbing module has combined sound absorption parameters configured to absorb sound waves in a second frequency band; wherein the lower limit of the second frequency band is less than the lower limit of the first frequency band.

[0024] The above-mentioned sound-absorbing structure, by combining the first and second sound-absorbing elements to form a third sound-absorbing module, avoids the introduction of additional sound-absorbing elements, thereby reducing the overall size of the sound-absorbing structure. The small size of the sound-absorbing structure not only reduces material usage and manufacturing costs, but also makes it easier to meet lightweight requirements and reduces construction difficulty. It also helps expand the internal free sound field when used in anechoic chambers, thereby facilitating various acoustic work and acoustic experiments. Furthermore, by rationally setting the intrinsic sound absorption parameters and combined sound absorption parameters, the lower limit of the sound absorption frequency band of the third sound-absorbing module is lower than the lower limit of the sound absorption frequency band of the intrinsic sound absorption elements, which helps achieve better low-frequency sound absorption performance while ensuring mid- and high-frequency sound absorption. Furthermore, the intrinsic sound absorption parameters and combined sound absorption parameters can be adjusted according to the target sound absorption frequency band. Therefore, the above-mentioned sound-absorbing structure also has strong frequency design adjustability, which helps meet different customized sound absorption requirements.

[0025] In a third aspect, the present application provides an anechoic chamber comprising at least one interior wall panel, a bottom plate, and a sound absorbing structure as described in any of the above embodiments provided on at least one of the interior wall panels and / or the bottom plate.

[0026] The above-mentioned anechoic chamber, by providing the above-mentioned sound-absorbing structure on at least one indoor wall panel and / or floor, is conducive to achieving better low-frequency sound absorption performance while having medium and high-frequency sound absorption effects; at the same time, since the overall thickness of the above-mentioned sound-absorbing structure is much smaller than the thickness of traditional sound-absorbing components when achieving basically the same sound absorption effect, the above-mentioned anechoic chamber also has a larger free sound field, which is conducive to the development of various acoustic work and acoustic experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the implementation methods of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the implementation methods or the description of the prior art. Obviously, the drawings described below are only some implementation methods recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 This is a structural diagram of an embodiment of the present application;

[0029] Figure 2 A schematic top view of a sound absorbing assembly according to an embodiment of the present application;

[0030] Figure 3 for Figure 2 A schematic cross-sectional view of the AA plane of the sound absorbing component;

[0031] Figure 4A schematic top view of a sound-absorbing wedge according to an embodiment of the present application;

[0032] Figure 5 for Figure 4 A schematic cross-sectional view of the BB surface of the sound-absorbing wedge;

[0033] Figure 6 A schematic diagram of a sound absorption model according to an embodiment of the present application;

[0034] Figure 7 A schematic diagram of the arrangement of a sound absorbing component and a sound absorbing wedge according to an embodiment of the present application;

[0035] Figure 8 This is a schematic diagram of the arrangement of a sound absorbing component and a sound absorbing wedge according to another embodiment of the present application;

[0036] Figure 9 This is a schematic diagram of the arrangement of a sound absorbing component and a sound absorbing wedge according to another embodiment of the present application;

[0037] Figure 10 This is a schematic diagram of the arrangement of a sound absorbing component and a sound absorbing wedge according to another embodiment of the present application;

[0038] Figure 11 A schematic diagram of a sound absorption coefficient simulation curve of a specific embodiment of the present application;

[0039] Figure 12 for Figure 11 Schematic diagram of the sound absorption coefficient measurement curve of the specific embodiment in a reverberation chamber.

[0040] Component number description:

[0041] 100. Sound absorbing structure, 110. Housing, 120. Sound absorbing assembly, 121. Perforated plate, 122. Non-woven fabric, 123. Second sound absorbing material, 124. First micro-perforated plate assembly, 130. Sound absorbing wedge, 131. Second micro-perforated plate, 132. Non-woven fabric, 133. First sound absorbing material, 134. Perforated plate, 135. Bottom plate;

[0042] AP, apex, BP, base. DETAILED DESCRIPTION

[0043] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0046] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0047] The present embodiment provides an improved sound-absorbing structure. By incorporating at least two microperforated plates, this facilitates broadband absorption of low- and medium-frequency sound waves. Furthermore, the sound-absorbing wedge can be shortened for high- and medium-frequency sound waves. This ensures efficient absorption of high- and medium-frequency sound waves while ensuring impedance matching from tip to base. This reduces the height of the wedge, thereby reducing the overall size of the sound-absorbing structure and facilitating its manufacture, transportation, storage, and wall installation. Furthermore, the present application utilizes the microperforated plates on the sound-absorbing wedge in combination with the microperforated plates in the sound-absorbing assembly to form a double-layer microperforated plate sound-absorbing structure, further reducing the space occupied by the microperforated plates and reducing the overall size of the sound-absorbing structure.

[0048] like Figures 1 to 5As shown, an embodiment of the present application provides a sound absorbing structure 100, which is provided in order along the propagation direction of sound waves: a sound absorbing assembly 120, whose surface on the sound wave exit side is provided with a first microperforated plate assembly 124, and the first microperforated plate assembly 124 has one or more first microperforated plates; and at least one sound absorbing wedge 130, whose surface on the sound wave incident side is provided with at least one second microperforated plate 131 opposite to the at least one first microperforated plate in the first microperforated plate assembly 124, and whose surface on the sound wave exit side is provided with a bottom plate 135 opposite to the second microperforated plate 131. A first cavity is formed between the first microperforated plate 124 and the second microperforated plate 131 opposite thereto, and a second cavity is formed between the second microperforated plate 131 and the bottom plate 135 opposite thereto, and a first sound absorbing material 133 is provided in the second cavity.

[0049] Compared to conventional sound-absorbing wedges, the aforementioned sound-absorbing structure 100 can have a smaller size. For example, it can be approximately half the size (or height / thickness) of a conventional sound-absorbing wedge, breaking through the size limitations of conventional sound-absorbing wedge designs. Under certain structural parameters, it can even reach approximately one-third the size of a conventional sound-absorbing wedge at the same cutoff frequency. Therefore, when the sound-absorbing structure 100 of the present application, with comparable or better sound-absorbing performance, is used in an anechoic chamber, a larger free sound field can be obtained, facilitating various acoustic work and acoustic experiments. Furthermore, the small size of the sound-absorbing structure 100 can reduce material usage, lower production costs, and more easily meet lightweight requirements, thereby reducing construction difficulty. Furthermore, the structural parameters of the sound-absorbing structure 100 can be adjusted according to the target sound absorption frequency band. Therefore, the sound-absorbing structure also has strong frequency design adjustability, facilitating the satisfaction of different customized sound absorption requirements.

[0050] For example, the principle of sound absorption achieved by the double-layer microperforated plate sound absorption structure formed by the combination of the first microperforated plate and the second microperforated plate 131 in the first microperforated plate assembly 124 can be expressed as follows: sound waves enter the back cavity of the microperforated plate through the perforations on the microperforated plate. When the sound frequency is close to the resonance frequency of the back cavity, the air in the micropores repeatedly rubs against the hole wall, and heat loss is generated through the thermoviscous effect, thereby dissipating heat energy to achieve the purpose of sound absorption; the double-layer microperforated plate can produce multiple absorption peaks with high sound absorption coefficients in the frequency spectrum, which is conducive to slowing down the attenuation of the sound absorption coefficient at both ends of the absorption peak and achieving broadband sound absorption.

[0051] Furthermore, the first sound absorbing material 133 can maximize its high-frequency sound absorption function through the impedance matching characteristics of the sound absorbing wedge 130 itself, while greatly reducing the size of the first sound absorbing material 133. Optionally, the first sound absorbing material 133 can be a porous sound absorbing material, such as a fibrous porous sound absorbing material (such as glass wool or mineral wool) or a foam porous sound absorbing material (such as polyurethane foam or phenolic foam).

[0052] For example, the four structural parameters of the micro-perforated plate, namely, the perforation diameter, perforation ratio, plate thickness and cavity behind the plate, mainly affect the sound absorption performance, resonance frequency and sound absorption bandwidth of the micro-perforated plate. Figure 6 As shown, a first cavity is formed between the first micro-perforated plate and the sound-absorbing wedge. Since the cavity depths of the first and second cavities will change with the change of the incident position of the sound wave, the midpoint O of the oblique line O1O2 can be taken as the overall equivalent point, and the equivalent back-plate cavity depths D1 and D2 can be determined. The double-layer micro-perforated plate sound-absorbing structure of the present application can calculate the structural parameters of the resonant sound absorber by determining the resonant frequency and the sound absorption coefficient at the resonant frequency. Specifically, the double-layer micro-perforated plate sound-absorbing structure of the present application can have two absorption peaks, and the corresponding resonant frequencies f1 and f2 can be expressed as:

[0053]

[0054] Among them, P1 and P2 are perforation rates, and t1 and t2 are plate thicknesses.

[0055] Furthermore, the sound absorption coefficient α of the sound absorbing structure 100 at the resonant frequency is the maximum value within the effective sound absorption frequency band and can be calculated using the following formula:

[0056] α=1-|(Z s -1) / (Z s +1)| 2 (3)

[0057] Among them, Z s The overall acoustic impedance of the sound absorbing structure 100 needs to be calculated by the characteristic impedance Z of the micro-perforated part. MPP And the characteristic impedance Z of the cavity behind the board c Impedance Z of the first sound-absorbing material lining behind the board p To determine the characteristic impedance Z of the cavity behind the board c It can be determined by the characteristic wave number k of air and the cavity depth D. For example, Z MPP , Z c , Z p They can be determined by the following formulas:

[0058] Z c =-j cot(kD) (4)

[0059]

[0060] Among them, η, ρ, c, γ, and P0 are respectively the air dynamic viscosity, air density, sound speed in air, specific heat ratio of air, and air pressure, α ∞ ,σ, λ, λ p are the material’s tortuosity, resistivity, porosity, viscous characteristic length, and thermal characteristic length, ω is the angular frequency, d is the pore size, and k m is the pore constant.

[0061]

[0062] For example, the ratio of the structural dimensions of the sound-absorbing structure 100 determines that D1 / D2 is approximately 1 / 2. Based on processing considerations, the perforation diameter should be greater than or equal to the thickness of the micro-perforated plate. When these are equal, the acoustic performance is optimal. The four-unknown homogeneous nonlinear equation system determined by equations (1)-(7) can be used to determine the perforation diameter and perforation ratio using MATLAB numerical analysis software.

[0063] For example, the micro-perforated plate may include a metal micro-perforated plate or a non-metal micro-perforated plate. For example, the metal micro-perforated plate may include a steel plate, an iron plate, an aluminum alloy plate, etc., while the non-metal micro-perforated plate may include an organic glass plate, a plastic plate, a wood plate, a carbon fiber composite plate, etc. It is understood that the plate used in the sound-absorbing structure 100 can be made of materials such as plastic and metal according to fire protection and process requirements.

[0064] In some embodiments of the present application, Figures 7 to 10 As shown, the sound absorbing assembly 120 includes multiple sound absorbing units arranged in a reference plane perpendicular to the direction of sound wave propagation. The sound-wave-emitting surfaces of the sound absorbing units are provided with first microperforated plates. The sound absorbing structure 100 includes multiple sound absorbing wedges 130 arranged in a plane parallel to the reference plane. Each sound absorbing wedge corresponds to a sound absorbing unit, and the sound-wave-incident surface of each sound absorbing wedge 130 is provided with at least one second microperforated plate 131, opposite the first microperforated plate. By proportionally expanding the sound absorbing structure 100 in at least one direction, the overall sound absorption performance of the sound absorbing structure 100 is substantially unaffected, thereby adapting to varying wall installation dimensions.

[0065] Optional, such as Figure 7As shown, the sound absorbing assembly 120 includes a plurality of sound absorbing units arranged along the x-direction within a reference plane, and a first micro-perforated plate is provided on the surface of the sound absorbing unit on the sound wave exit side. Correspondingly, the sound absorbing structure 100 also includes a plurality of sound absorbing wedges 130 arranged along the x-direction within a plane parallel to the reference plane, with each sound absorbing wedge 130 corresponding to each sound absorbing unit. At least one second micro-perforated plate 131 opposite to the first micro-perforated plate is provided on the surface of the sound wave incident side of the sound absorbing wedge 130.

[0066] Optional, such as Figure 8 As shown, the sound absorbing assembly 120 includes a plurality of sound absorbing units arranged along the x-direction and the y-direction within a reference plane, and a first micro-perforated plate is provided on the surface of the sound absorbing unit on the sound wave exit side. Correspondingly, the sound absorbing structure 100 also includes a plurality of sound absorbing wedges 130 arranged along the x-direction and the y-direction within a plane parallel to the reference plane, and each sound absorbing wedge 130 corresponds to each sound absorbing unit one by one. The surface of the sound absorbing wedge 130 on the sound wave incident side is provided with at least one second micro-perforated plate 131 opposite to the first micro-perforated plate.

[0067] Optional, such as Figure 9 As shown, in Figure 8 Based on the illustrated embodiment, the arrangement orientation of at least one sound absorbing wedge 130 is different.

[0068] Optional, such as Figure 10 As shown, in Figure 8 On the basis of the illustrated embodiment, the number of sound absorbing units arranged along the x direction and along the y direction is different, and correspondingly, the number of sound absorbing wedges arranged along the x direction and along the y direction is also different.

[0069] Depending on the size and geometric shape of the wall, the basic combination scheme given above can be adopted but is not limited to it. The sound absorbing structure 100 can be proportionally expanded in different directions or the installation orientation can be adjusted according to the actual installation situation.

[0070] In some embodiments of the present application, Figure 4 and Figure 5As shown, the sound-absorbing wedge 130 is sequentially arranged along the direction of sound wave propagation: a tip AP, whose surface on the sound wave incident side is provided with at least one second microperforated plate 131; and a base BP, connected to the tip AP and whose surface on the sound wave exit side is provided with a bottom plate 135. The ratio of the height of the tip AP to the height of the base BP is less than 4. Optionally, the tip AP is generally triangular pyramid-shaped, while the base BP is box-shaped, with perforated plates 134 disposed on at least one of its four peripheral surfaces. Because the double-layer microperforated plate sound-absorbing structure achieves broadband absorption of mid- and low-frequency sound waves, the sound-absorbing wedge 130 can be shortened for mid- and high-frequency sound waves. This reduces the height of the wedge 130 while ensuring impedance matching from the tip to the base, thereby reducing the overall size of the sound-absorbing structure 100. Furthermore, for some cutoff frequencies (eg, 100 Hz), the ratio of the height of the tip AP to the height of the base BP may be less than or equal to 2. In this case, the size of the sound absorbing wedge 130 is approximately one-third of that of a traditional sound absorbing wedge.

[0071] In some embodiments of the present application, Figure 4 and Figure 5 As shown, the surface of the tip AP on the sound wave incident side includes a first surface and a second surface arranged at an angle, both of which are provided with second microperforated plates 131. Providing second microperforated plates 131 on both surfaces of the tip AP on the sound wave incident side facilitates full utilization of the space occupied by the sound absorbing wedge 130, forming as many double-layer microperforated plate sound absorbing structures as possible within the limited space, thereby further broadening the sound absorption bandwidth of the sound absorbing structure 100 for mid- and low-frequency sound waves.

[0072] In some embodiments of the present application, Figure 5 As shown, at least one layer of non-woven fabric 132 is disposed between the first sound-absorbing material 133 and the second microperforated plate 131. This arrangement modifies the radiation impedance of the microperforated ends and the acoustic impedance of the second cavity, thereby achieving a wider sound absorption band. Furthermore, it ensures uniform loading of the first sound-absorbing material 133, preventing fibers from overflowing and affecting the external environment or clogging the microperforations, which could affect sound absorption performance.

[0073] In some embodiments of the present application, Figure 2 and Figure 3As shown, the sound absorption assembly 120 includes one or more sound absorption units, which are sequentially arranged along the propagation direction of the sound waves, including a perforated plate 121 and a first micro-perforated plate. A third cavity is formed between the perforated plate 121 and the first micro-perforated plate, and a second sound absorption material 123 is disposed within the third cavity. Optionally, the second sound absorption material 123 may also be a porous sound absorption material. The specific material of the second sound absorption material 123 can be referred to above for the description of the first sound absorption material 133 and will not be repeated here. With this arrangement, after passing through the sound absorption assembly 120, the sound waves reach the surface of the sound absorption wedge 130. A portion of the sound waves is reflected from the surface, resulting in secondary absorption between the first cavity and the second sound absorption material 123. This further reduces the attenuation of the absorption peak of mid- and low-frequency sound waves and broadens the absorption peak of mid- and low-frequency sound waves.

[0074] Furthermore, at least one layer of non-woven fabric 122 is disposed between the second sound-absorbing material 123 and the first microperforated plate. This arrangement modifies the radiation impedance of the microperforated ends and the acoustic impedance of the first cavity, thereby achieving a wider sound absorption band. Furthermore, it ensures uniform loading of the second sound-absorbing material 123, preventing fiber overflow from affecting the external environment or clogging the microperforations, which could affect sound absorption performance.

[0075] In some embodiments of the present application, Figure 1 As shown, the sound-absorbing structure 100 also includes a housing 110 for accommodating a sound-absorbing assembly 129 and at least one sound-absorbing wedge 130. At least one surface of the housing 110 is flat or curved. This facilitates adapting to the shape of the wall on which it is installed and helps the sound-absorbing assembly 110 achieve better impedance matching, thereby improving sound absorption performance. Optionally, when the sound-absorbing assembly 110 is a flat sound-absorbing plate, the top surface of the plate can be curved; optionally, when the sound-absorbing assembly 110 is a sound-absorbing wedge, the side surfaces of the wedge can be curved. Furthermore, when all surfaces of the housing 110 are flat, the sound-absorbing structure 100 can have a flat surface and a regular appearance, facilitating product transportation, storage, and wall installation.

[0076] The following is an example of a specific embodiment to illustrate the sound absorption effect of the sound absorption structure 100 of the present application:

[0077] like Figures 1 to 5As shown, the sound-absorbing assembly 110 is box-shaped, surrounded by 1.2mm-thick sealed aluminum plates to enhance sound reflection within the first cavity. The upper surface is a 1.2mm-thick perforated aluminum panel, serving as the outward-facing sound-absorbing surface of the overall structure, through which sound waves enter. The lower surface is a 0.8mm-thick micro-perforated aluminum panel. The sound-absorbing wedge 130 is a shortened wedge positioned below the sound-absorbing assembly 110. Its tip AP is an overall triangular pyramid shape, while its base BP is box-shaped. The height ratio of the tip AP to the base BP is 2:1. The wedge's sidewalls (non-sound-absorbing surface) and bottom plate are both 1.2mm-thick aluminum plates, while the wedge's sound-absorbing surface is a 0.8mm-thick micro-perforated panel. In this test embodiment, the perforation rate of the first and second micro-perforated plates 131 can be 0.1% to 0.4%, the perforation diameter is 0.8 mm to 1 mm, the thickness of the sound absorbing structure 100 is 350 mm, the thickness of the sound absorbing component 110 is 50 mm, D1 is 100 mm, and D2 is 200 mm.

[0078] Figure 11 A schematic diagram of simulation curves comparing the sound absorption coefficients of a conventional 350mm thick sound-absorbing wedge and a flat sound-absorbing plate in the frequency domain of 100Hz to 5000Hz is shown. The flat sound-absorbing plate is a flat-plate sound-absorbing unit made of sound-absorbing materials (such as polyester fiber, glass fiber, mineral wool, or foam plastic) that convert sound energy into other forms of energy, such as heat. As can be seen, compared to conventional wedges and flat sound-absorbing plates of the same size, at a cutoff frequency of 100Hz, the sound-absorbing structure 100 of the present application (i.e., the super-structured broadband composite sound absorber described in the figure) exhibits excellent mid- and low-frequency sound absorption while maintaining mid- and high-frequency sound absorption performance. The sound absorption coefficient at the cutoff frequency is above 0.85, significantly outperforming the sound absorption performance of conventional wedges and flat sound-absorbing plates of the same size.

[0079] Figure 12 A schematic diagram of the sound absorption coefficient measurement curve of the sound-absorbing structure 100 of the present application in a reverberation chamber is shown. As can be seen, the sound absorption coefficient of the sound-absorbing structure 100 (i.e., the super-structured broadband composite sound absorber in the figure) is above 1 across the entire frequency range. The low-frequency sound absorption design is also very effective, with a sound absorption coefficient of 1.32 at a cutoff frequency of 100 Hz, fully meeting the requirements for efficient sound absorption across the entire frequency range.

[0080] The present application also provides a sound absorbing structure comprising: a first sound absorbing module including a first sound absorbing element; a second sound absorbing module including a second sound absorbing element disposed opposite the first sound absorbing element and combined with the first sound absorbing element to form a third sound absorbing module; and an intrinsic sound absorbing element disposed on a side of the second sound absorbing element away from the first sound absorbing element. The intrinsic sound absorbing element has intrinsic sound absorption parameters configured to absorb sound waves in a first frequency band; and the third sound absorbing module has combined sound absorption parameters configured to absorb sound waves in a second frequency band. The lower limit of the second frequency band is lower than the lower limit of the first frequency band.

[0081] The above-mentioned sound-absorbing structure, by combining the first and second sound-absorbing elements to form a third sound-absorbing module, avoids the introduction of additional sound-absorbing elements, thereby reducing the overall size of the sound-absorbing structure. The small size of the sound-absorbing structure not only reduces material usage and manufacturing costs, but also makes it easier to meet lightweight requirements and reduces construction difficulty. It also helps expand the internal free sound field when used in anechoic chambers, thereby facilitating various acoustic work and acoustic experiments. Furthermore, by rationally setting the intrinsic sound absorption parameters and combined sound absorption parameters, the lower limit of the sound absorption frequency band of the third sound-absorbing module is lower than the lower limit of the sound absorption frequency band of the intrinsic sound absorption elements, which helps achieve better low-frequency sound absorption performance while ensuring mid- and high-frequency sound absorption. Furthermore, the intrinsic sound absorption parameters and combined sound absorption parameters can be adjusted according to the target sound absorption frequency band. Therefore, the above-mentioned sound-absorbing structure also has strong frequency design adjustability, which helps meet different customized sound absorption requirements.

[0082] For example, the intrinsic sound absorption element can be a component within the sound-absorbing wedge that can utilize its inherent sound absorption properties, such as a porous sound-absorbing material with a wedge shape. The intrinsic sound absorption parameters also include the tip height and base height of the porous sound-absorbing material. The combined sound absorption parameters include the perforation diameter, perforation ratio, cavity depth, and plate thickness of the microperforated plate, which are essentially the same as the structural parameters of the microperforated plate described above and are not further detailed here.

[0083] An embodiment of the present application further provides a anechoic chamber, comprising at least one indoor wall panel, a bottom plate, and a sound absorbing structure as described in any of the above embodiments, which is arranged on at least one indoor wall panel and / or bottom plate.

[0084] The above-mentioned anechoic chamber, by providing the above-mentioned sound-absorbing structure on at least one indoor wall panel and / or floor, is conducive to achieving better low-frequency sound absorption performance while having medium and high-frequency sound absorption effects; at the same time, since the overall thickness of the above-mentioned sound-absorbing structure is much smaller than the thickness of traditional sound-absorbing components when achieving basically the same sound absorption effect, the above-mentioned anechoic chamber also has a larger free sound field, which is conducive to the development of various acoustic work and acoustic experiments.

[0085] For example, the interior wall panel can be any one of a wall, a wallboard, an aluminum alloy plate, a wooden board, or a suspended ceiling. For a broader understanding, the interior wall panel can also be a non-removable plate-like component of the anechoic chamber. For example, the bottom plate can be any one of a floor, an aluminum alloy plate, or a tile (including ceramic tile). For a broader understanding, the bottom plate can also be a non-removable plate-like component of the anechoic chamber.

[0086] For example, when the anechoic chamber adopts a semi-anechoic setting, the aforementioned sound-absorbing structure may be provided on all wall panels except the bottom panel; and when the anechoic chamber adopts a full-anechoic setting, the aforementioned sound-absorbing structure may be provided on the bottom panel and all wall panels.

[0087] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A sound absorbing structure, characterized in that: The following are arranged in order along the propagation direction of the sound wave: A sound absorbing component, wherein a first micro-perforated plate component is provided on a surface of a sound wave exiting side of the sound absorbing component, wherein the first micro-perforated plate component has one or more first micro-perforated plates; as well as, At least one sound absorbing wedge, wherein the surface of the sound absorbing wedge on the sound wave incident side is provided with at least one second micro-perforated plate opposite to at least one first micro-perforated plate in the first micro-perforated plate assembly, and the surface of the sound wave exit side of the sound absorbing wedge is provided with a bottom plate opposite to the second micro-perforated plate; A first cavity is formed between the first micro-perforated plate and the second micro-perforated plate opposite thereto, a second cavity is formed between the second micro-perforated plate and the bottom plate opposite thereto, and a first sound absorbing material is arranged in the second cavity.

2. The sound absorbing structure according to claim 1, characterized in that: The sound absorbing assembly includes a plurality of sound absorbing units arranged in a reference plane perpendicular to the propagation direction of the sound wave, and a first micro-perforated plate is provided on the surface of the sound wave exit side of the sound absorbing unit; The sound absorbing structure includes a plurality of sound absorbing wedges arranged in a plane parallel to the reference plane, the sound absorbing wedges are arranged in one-to-one correspondence with the sound absorbing units, and at least one second micro-perforated plate opposite to the first micro-perforated plate is arranged on the surface of the sound wave incident side of the sound absorbing wedge.

3. The sound absorbing structure according to claim 1 or 2, characterized in that: The sound absorbing wedges are arranged in sequence along the propagation direction of the sound wave: A tip portion, the surface of which on the sound wave incident side is provided with at least one of the second micro-perforated plates; A base part connected to the tip part, and having the bottom plate disposed on the surface of the sound wave exit side; Wherein, the ratio of the height of the tip to the height of the base is less than 4; or, the ratio of the height of the tip to the height of the base is less than or equal to 2.

4. The sound absorbing structure according to claim 3, characterized in that: The surface of the tip portion at the sound wave incident side includes a first surface and a second surface arranged at an angle, and the first surface and the second surface are both provided with the second micro-perforated plate.

5. The sound absorbing structure according to claim 4, characterized in that: The vertical distance between the center of the second micro-perforated plate and the first micro-perforated plate is the equivalent cavity depth D1 of the first cavity, and the vertical distance between the center of the second micro-perforated plate and the bottom plate is the equivalent cavity depth D2 of the second cavity, where D1 / D2 is 1 / 2.

6. The sound absorbing structure according to claim 1 or 2, characterized in that: At least one layer of non-woven fabric is disposed between the first sound absorbing material and the second micro-perforated plate.

7. The sound absorbing structure according to claim 1, characterized in that: The sound absorbing component includes one or more sound absorbing units, and the sound absorbing unit is provided with a perforated plate and the first micro-perforated plate in sequence along the propagation direction of the sound wave, wherein a third cavity is formed between the perforated plate and the first micro-perforated plate, and a second sound absorbing material is provided in the third cavity.

8. The sound absorbing structure according to claim 7, characterized in that: At least one layer of non-woven fabric is disposed between the second sound absorbing material and the first micro-perforated plate.

9. The sound absorbing structure according to claim 1, characterized in that: The sound absorbing structure further comprises a shell for accommodating the sound absorbing assembly and the at least one sound absorbing wedge, and at least one surface of the shell is a plane or a curved surface.

10. An anechoic chamber, characterized in that: The invention comprises at least one indoor wall panel, a bottom plate, and the sound absorbing structure according to any one of claims 1 to 9 arranged on at least one of the indoor wall panel and / or the bottom plate.

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