Sound wave absorbing structure, sound transmission device, component and preparation method

Abstract

This invention relates to a sound wave absorbing structure, a sound transmission device, an instrument, and a method for its fabrication. The sound wave absorbing structure includes a plurality of sound wave absorbing materials spaced apart along a predetermined axis; the spacing between adjacent sound wave absorbing materials satisfies a predetermined condition along the extension direction of the predetermined axis; each sound wave absorbing material has a first tilt angle relative to the predetermined axis, and a sound wave incident on each sound wave absorbing material has a second tilt angle relative to the predetermined axis; when the first tilt angle and the second tilt angle are symmetrical about the predetermined axis, the first tilt angle is the absorption tilt angle of the sound wave absorbing material; wherein at least a portion of the sound wave absorbing materials are configured to be tilted relative to the predetermined axis within a range of their absorption tilt angle plus or minus a predetermined angle. The above-described sound wave absorbing structure can achieve sound absorption and noise reduction in a target direction.

Description

Technical Field

[0001] This invention relates to the field of sound wave absorption technology, and in particular to a sound wave absorption structure, a sound transmission device, an instrument, and a method for its fabrication. Background Technology

[0002] Most existing sound-absorbing metamaterials have symmetrical sound absorption properties, which may not be suitable for certain scenarios. For example, sometimes it is necessary to directionally interfere with sound from a certain direction without affecting the transmission of sound waves in other directions.

[0003] Furthermore, traditional metamaterials for sound absorption are typically fabricated based on resonance, often resulting in narrow bandwidth. To expand the operating frequency range, several measures have been taken, such as utilizing coupled folded Fabry-Pérot channels or Helmholtz resonators. However, these designs usually require coupling multiple resonators and complex structural designs, increasing the fabrication difficulty. In addition, these sound-absorbing structures typically exhibit symmetrical sound absorption characteristics, making it difficult to achieve asymmetrical sound absorption properties. Summary of the Invention

[0004] To address at least one of the aforementioned problems, the present invention aims to provide an improved sound wave absorbing structure, sound transmission device, instrument, and preparation method to effectively shield sound waves in the target direction.

[0005] In a first aspect, this application provides an acoustic wave absorbing structure, comprising:

[0006] Multiple sound wave absorbing materials are spaced apart along a preset axis;

[0007] Furthermore, along the extension direction of the preset axis, the spacing ω between two adjacent sound wave absorbing materials satisfies: t < ω < λ, where t represents the thickness of the sound wave absorbing material and λ represents the wavelength of the incident sound wave;

[0008] Furthermore, each of the sound wave absorbing materials has a first tilt angle relative to the preset axis, and the sound wave incident on each of the sound wave absorbing materials has a second tilt angle relative to the preset axis. When the first tilt angle and the second tilt angle are symmetrical about the preset axis, the first tilt angle is the absorption tilt angle of the sound wave absorbing material.

[0009] In this embodiment, at least a portion of the sound wave absorbing material is configured to be tilted relative to the preset axis within a range of its absorption tilt angle plus or minus a preset angle.

[0010] The aforementioned sound wave absorption structure, by tilting at least a portion of the sound wave absorbing material relative to a preset axis within a range of its absorption tilt angle plus or minus a preset angle, enables the sound wave absorption structure to absorb sound waves in the target direction based on the reciprocity law, thereby achieving sound absorption and noise reduction in the target direction. At the same time, the aforementioned sound wave absorption structure can also allow sound waves propagating along the tilt direction of the sound wave absorbing material (the direction symmetrical to the perpendicular line of the target direction about the preset axis) to pass through the sound wave absorption structure, thereby achieving an asymmetrical sound absorption effect.

[0011] In one embodiment, each of the sound-absorbing materials is configured to be tilted relative to the preset axis within a range of its absorption tilt angle plus or minus a preset angle.

[0012] In one embodiment, the absorption tilt angle is greater than 0° and less than 90°.

[0013] In one embodiment, the absorption tilt angle is greater than or equal to 20° and less than 90°.

[0014] In one embodiment, the preset angle is less than or equal to 15°.

[0015] In one embodiment, t ≤ ω / 5.

[0016] In one embodiment, the operating frequency f of the acoustic wave absorbing structure is... w It is negatively correlated with the spacing ω between two adjacent acoustic absorbing materials.

[0017] In one embodiment, the sound-absorbing material includes at least one of micro-perforated plates, textile sound-absorbing materials, and foamed metals.

[0018] In one embodiment, the sound wave absorbing material includes a first end near the incident side of the sound wave and a second end near the emitting side of the sound wave. The sound wave absorbing structure also includes a first rigid boundary disposed near the second end, and at least a portion of the first rigid boundary extends in a direction parallel to the preset axis.

[0019] In one embodiment, at least a portion of the second end of the acoustic wave absorbing material is disposed in contact with the first rigid boundary.

[0020] In one embodiment, the acoustic wave absorbing structure further includes a second rigid boundary intersecting the first rigid boundary or an extension of the first rigid boundary, and at least a portion of the second rigid boundary is located on the side of the first rigid boundary closer to the acoustic wave absorbing material.

[0021] In one embodiment, a plurality of second rigid boundaries are provided circumferentially along the first rigid boundary, and the plurality of second rigid boundaries together with the first rigid boundary form a cavity for accommodating the plurality of sound wave absorbing materials that opens toward the incident side of the sound wave.

[0022] In one embodiment, the length of the plurality of acoustic absorbing materials in a direction perpendicular to the preset axis is greater than or equal to a response length, the response length being determined at least based on the bulk modulus of air, the effective bulk modulus of the plurality of acoustic absorbing materials in the static limit, and the wavelength of the incident sound wave in air.

[0023] In one embodiment, it further includes: a first adjustment mechanism coupled to the plurality of acoustic absorbing materials for adjusting the first tilt angle; and / or a second adjustment mechanism coupled to the plurality of acoustic absorbing materials for adjusting the spacing.

[0024] Secondly, this application also provides a method for preparing a sound wave absorbing structure, comprising: obtaining a plurality of sound wave absorbing materials spaced apart along a preset axis; wherein, along the preset axis, the distance ω between two adjacent sound wave absorbing materials satisfies: t < ω < λ, where t represents the thickness of the sound wave absorbing material and λ represents the wavelength of the incident sound wave; obtaining the absorption tilt angle of the sound wave absorbing material; wherein each sound wave absorbing material has a first tilt angle relative to the preset axis, and the sound wave incident on each sound wave absorbing material has a second tilt angle relative to the preset axis, wherein when the first tilt angle and the second tilt angle are symmetrical about the preset axis, the first tilt angle is the absorption tilt angle of the sound wave absorbing material; and causing at least a portion of the sound wave absorbing materials to be tilted relative to the preset axis within a range of their absorption tilt angle plus or minus a preset angle.

[0025] The above-described method for fabricating a sound wave absorbing structure involves calculating the absorption angle of the sound wave absorbing material based on the second tilt angle of the incident sound wave relative to a preset axis, and then setting the first tilt angle of the sound wave absorbing material relative to the preset axis based on the absorption tilt angle, thereby obtaining the aforementioned sound wave absorbing structure. This method allows for the fabrication of a sound-absorbing structure designed based on the propagation direction of the incident sound wave, achieving directional sound absorption.

[0026] In one embodiment, the method further includes: obtaining the operating frequency f of the acoustic wave absorption structure. w According to the operating frequency f w Adjust the spacing ω between two adjacent acoustic wave absorbing materials; where, f w It is negatively correlated with ω.

[0027] In one embodiment, the acoustic absorbing material includes a first end near the incident side of the acoustic wave and a second end near the emitting side of the acoustic wave. The preparation method further includes: setting a first rigid boundary near the second end; wherein at least a portion of the first rigid boundary extends in a direction parallel to the preset axis.

[0028] In one embodiment, the method further includes: providing a second rigid boundary that intersects the first rigid boundary or an extension of the first rigid boundary; wherein at least a portion of the second rigid boundary is located on the side of the first rigid boundary closer to the acoustic absorbing material.

[0029] Thirdly, this application also provides a sound transmission device, comprising: an incident surface and an exit surface of a sound wave disposed opposite to each other; and a sound absorption structure as described above disposed between the incident surface and the exit surface of the sound wave; the sound transmission device is adapted to transmit sound waves incident along a first direction and shield sound waves incident along a second direction, wherein the first direction is parallel to the tilt direction of the sound absorption material, and the first direction and the second direction are symmetrical about the perpendicular line of the preset axis.

[0030] The aforementioned sound transmission device, through the aforementioned sound wave absorption structure, can achieve sound wave transmission in the first direction while shielding sound waves in the second direction, thus achieving an asymmetrical sound transmission effect.

[0031] Fourthly, this application also provides a device comprising: a receiving cavity; a target sound source disposed in the receiving cavity; and a sound wave absorbing structure as described above for absorbing sound waves emitted by the target sound source.

[0032] The aforementioned device can absorb and reduce noise from its internal noise sources through the aforementioned acoustic absorption structure, thereby improving the device's noise control performance. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 Figure (a) shows a schematic diagram of the sound-absorbing metamaterial using Fabry-Pérot channels;

[0035] Figure 1 Figure (b) is a schematic diagram of the sound-absorbing metamaterial using a Helmholtz resonant cavity;

[0036] Figure 2 This is a schematic diagram of the acoustic wave absorption structure according to an embodiment of this application;

[0037] Figure 3 This is a schematic diagram of sound absorption based on the reciprocity principle according to an embodiment of this application;

[0038] Figure 4 The following are curves showing the variation of reflectivity, transmittance, and absorptivity of a sound-absorbing material according to an embodiment of this application under perpendicular sound wave incidence as a function of frequency.

[0039] Figure 5 Figure (a) is a function graph showing the absorptivity of an acoustic wave absorbing structure according to an embodiment of this application as a function of the acoustic wave incident angle and the complementary angle α of the first tilt angle;

[0040] Figure 5 Figure (b) is a function graph showing the reflectivity of an acoustic absorption structure according to an embodiment of this application as a function of the incident angle and frequency of the acoustic wave;

[0041] Figure 5 Figure (c) is a function graph showing the absorptivity of an acoustic absorption structure according to an embodiment of this application as a function of the incident angle and frequency of the acoustic wave.

[0042] Figure 6 Figure (a) is a simulated sound field distribution diagram of a sound wave absorbing structure according to an embodiment of this application when the sound wave is incident at ±45°.

[0043] Figure 6 Figure (b) is a simulated sound field distribution diagram of a sound wave absorption structure according to an embodiment of this application under a point sound source;

[0044] Figure 7 This is a schematic diagram illustrating the effect of using this embodiment of the present application as a superstructure venetian blind;

[0045] Figure 8 Figure (a) is a schematic diagram of the Gaussian acoustic beam experimental architecture of a metamorphic louver sample;

[0046] Figure 8 Figure (b) shows the curves of reflectivity, transmittance, and absorptivity as a function of frequency when sound waves are incident on the metamorphic louver sample at ±45°.

[0047] Figure 8 Figure (c) shows the transmission sound field distribution when sound waves of different frequencies are incident at 45° on the metamorphic louver sample.

[0048] Figure 8 Figure (d) shows the distribution of reflected sound fields when sound waves of different frequencies are incident at -45° on the metamorphic louver sample.

[0049] Figure 9Figure (a) is a schematic diagram of the point sound source experimental architecture of a metamorphic louver sample;

[0050] Figure 9 Figure (b) shows the transmitted sound field distribution of a point sound source in the sample without the superstructure louver (top) and the sample with the superstructure louver (bottom).

[0051] Figure 10 Figure (a) is a structural schematic diagram of Case 1 of this application (with a first rigid boundary set);

[0052] Figure 10 Figure (b) is a function of the absorption rate of Case 1 of this application as a function of the incident angle and operating frequency;

[0053] Figure 11 Figure (a) is a structural schematic diagram of Case 2 of this application (with a first rigid boundary and a second rigid boundary set);

[0054] Figure 11 Figure (b) shows the absorption rate of micro-perforated plates under perpendicular acoustic wave incidence as a function of frequency in Case 1 and Case 2.

[0055] Figure 11 Figure (c) shows the normalized intensity (color) and velocity field (white arrow) of Case 1 and Case 2 in a 330Hz simulation;

[0056] Figure 12 Figure (a) is a schematic diagram of the structure of the three-dimensional omnidirectional sound absorber proposed in this application based on Case 2;

[0057] Figure 12 Figure (b) shows the absorptivity of the three-dimensional omnidirectional sound absorber as a function of the incident angle and operating frequency when the sound wave is incident in the xz plane.

[0058] Figure 12 Figure (c) shows the absorptivity of the three-dimensional omnidirectional sound absorber as a function of the incident angle and operating frequency when the sound wave is incident in the yz plane.

[0059] Figure 13 Figure (a) is a schematic diagram of the impedance tube experimental architecture of a three-dimensional omnidirectional sound absorber;

[0060] Figure 13 Figure (b) shows a schematic diagram of the physical samples 1 and 2 of the three-dimensional omnidirectional sound absorber;

[0061] Figure 13 Figure (c) is a schematic diagram of the structure of sample 2;

[0062] Figure 13Figure (d) shows the absorption rate of sample 1 as a function of frequency under experimental and simulation conditions, as well as the absorption rate of sample 2 as a function of frequency under experimental and simulation conditions.

[0063] Component designation explanation:

[0064] 100. Sound wave absorbing structure; 101-102. Sound wave absorbing material;

[0065] 200. Type I omnidirectional acoustic wave absorption structure; 300. Type II omnidirectional acoustic wave absorption structure;

[0066] AX, preset axis, θ i 1. Sound wave incident angle, β. First tilt angle, α. Complementary angle of the first tilt angle, γ. Second tilt angle. Detailed Implementation

[0067] To make the technical solution and beneficial effects of the present invention more apparent and understandable, a detailed description is provided below by listing specific embodiments. The accompanying drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used in this application have the same meanings as those in the technical field to which this application pertains.

[0068] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0069] Sound absorption has long been a fundamental area of ​​acoustic research, widely applied in indoor acoustics and noise control engineering. Traditional porous materials, such as plastic foam, glass fiber, and mineral wool, rely on the dissipation of wave energy during propagation to achieve absorption. However, these materials require sufficient thickness to match the maximum operating wavelength. Some studies have proposed reducing thickness through local resonant structures, such as microperforated plate (MPP) resonators, which utilize the principle of resonance to achieve impedance matching within certain frequency ranges. However, the inherent strong dispersion of these structures limits the bandwidth of impedance modulation.

[0070] On the other hand, acoustic metamaterials have demonstrated an impressive ability to manipulate sound in unprecedented ways, leading to many interesting applications. In particular, acoustic metamaterials have overcome the limitations of traditional materials, opening up new avenues for designing sound absorbers. Several metamaterial-based sound absorbers have been proposed, including decorative films, bubbles in rubber, spiraling spatial structures, and Helmholtz resonators. However, these methods are limited by their resonance-based mechanisms and thus their operating frequency range. To achieve broadband sound absorption, traditional sound-absorbing metamaterials typically employ two methods:

[0071] (1) Coupled folding of the Fabry-Pérot channel

[0072] like Figure 1 As shown in Figure (a), when sound waves enter the Fabry-Pérot channel, they propagate repeatedly within the channel, resulting in reflections and interference. Due to folding and coupling, sound waves of different frequencies will interfere at different locations and depths, thus achieving broadband sound absorption.

[0073] (2) Coupled Helmholtz resonant cavity

[0074] like Figure 1 As shown in Figure (b), when a sound wave enters a Helmholtz resonator, it will be repeatedly reflected within the cavity, forming a standing wave. By designing resonators of different sizes and shapes, sound waves of different frequencies can be absorbed. By rationally coupling resonators of different sizes and shapes, good sound absorption performance can be achieved over a wide frequency range.

[0075] However, these designs typically require coupling multiple resonant cavities and complex geometries, increasing the difficulty of fabrication. Furthermore, these sound-absorbing structures usually exhibit symmetrical absorption characteristics, making it difficult to achieve asymmetrical absorption properties.

[0076] To address the aforementioned issues, this application utilizes a non-resonant method, considering various physical properties such as the dispersion and effective parameters of the prepared material, to provide a sound wave absorption structure designed based on the reciprocity principle. The sound wave absorption structure of this application possesses near-zero reflection asymmetric sound absorption characteristics (or directional sound absorption characteristics), and also features a wide operating frequency band and thin thickness.

[0077] In one embodiment, such as Figure 2As shown, the sound wave absorbing structure 100 includes a plurality of sound wave absorbing materials spaced apart along a preset axis AX; and, along the extension direction of the preset axis AX, the distance ω between two adjacent sound wave absorbing materials (such as sound wave absorbing material 101 and sound wave absorbing material 102) satisfies: t < ω < λ, where t represents the thickness of the sound wave absorbing material and λ represents the wavelength of the incident sound wave. Furthermore, each sound wave absorbing material has a first tilt angle β relative to the preset axis AX, and the sound wave incident on each sound wave absorbing material has a second tilt angle γ relative to the preset axis AX. When the first tilt angle β and the second tilt angle γ are symmetrical about the preset axis AX, the first tilt angle β is the absorption tilt angle of the sound wave absorbing material; wherein at least a portion of the sound wave absorbing materials are configured to be tilted relative to the preset axis AX within a range of their absorption tilt angle plus or minus a preset angle.

[0078] Based on the principle of reciprocity, Figure 3 As shown in the example, when a sound wave is incident on the sound wave absorbing structure 100 along a direction parallel to the surface of the incident material, the sound wave can be transmitted from the other side of the sound wave absorbing structure 100 with almost no reflection. At this time, the incident angle θ of the sound wave is... i This can be denoted as α1. When the sound wave is incident at an angle symmetrical to α1 about the normal (denoted as -α1), the sound wave will also enter the sound wave absorbing structure 100 with almost no reflection, and will be absorbed by the sound wave absorbing material in the sound wave absorbing structure 100, where R represents reflectivity, T represents transmittance, and H represents the thickness of the sound wave absorbing structure 100. At this time, the sound wave absorbing structure 100 is matched with the air impedance, α1 and the first tilt angle β are complementary, and -α1 and the second tilt angle γ are complementary, so the first tilt angle β and the second tilt angle γ are symmetrical about the preset axis AX, and the first tilt angle β is the absorption tilt angle of the sound wave absorbing material. When at least a portion of the sound-absorbing material is tilted relative to a preset axis AX within a range of its absorption tilt angle plus or minus a preset angle, this portion of the sound-absorbing material can achieve better absorption of sound waves incident at a certain angle (e.g., -α1). In other words, the sound-absorbing structure 100 can possess asymmetrical sound absorption characteristics for sound waves incident at angles α1 and -α1. If the sound dissipation provided by the sound-absorbing material is sufficiently large, it is beneficial to obtain a perfect sound absorption effect. For example, the upper limit of the preset angle can be 15°, and for example, the preset angle can be 3°, 5°, 8°, 10°, or 15°. On the other hand, by controlling the spacing between two adjacent sound-absorbing materials to be less than the wavelength of the incident sound wave and greater than the thickness of the sound-absorbing material, it is beneficial to further ensure that there is essentially no diffraction during sound wave transmission, thereby ensuring the sound absorption effect of the sound-absorbing structure 100.

[0079] For example, the sound wave absorbing structure 100 described above may further include a substrate, on which each sound wave absorbing material is fixedly disposed. Optionally, the first tilt angle of each sound wave absorbing material relative to the substrate is adjustable, thereby facilitating the achievement of better sound absorption effect for sound waves incident at different angles.

[0080] For example, sound-absorbing materials include at least one of micro-perforated plates, textile sound-absorbing materials, and foamed metals.

[0081] The sound wave absorbing structure 100 of this embodiment is configured such that at least a portion of the sound wave absorbing material is tilted relative to a preset axis AX within a range of its absorption tilt angle plus or minus a preset angle. This allows the sound wave absorbing structure 100 to absorb sound waves in the target direction based on the reciprocity law, thereby achieving sound absorption and noise reduction in the target direction. At the same time, the sound wave absorbing structure 100 can also allow sound waves propagating along the tilt direction of the sound wave absorbing material (the direction symmetrical to the perpendicular line of the target direction about the preset axis) to pass through the sound wave absorbing structure, thereby achieving an asymmetrical sound absorption effect.

[0082] In some embodiments, continue to refer to Figure 2 Each sound-absorbing material is configured to be tilted relative to a preset axis AX within a range of its absorption angle plus or minus a preset angle. Thus, when sound waves in the target direction are incident on different parts of the sound-absorbing structure 100, a better sound absorption effect can be achieved, thereby helping to improve the overall sound absorption characteristics of the sound-absorbing structure 100.

[0083] In some embodiments, the absorption tilt angle is greater than 0° and less than 90°, for example, the absorption tilt angle can be 10°, 20°, 30°, 40°, 50°, 60°, 70°, or 80°. If the absorption tilt angle is 0°, the sound wave absorbing material is set parallel to the sound wave incident surface of the sound wave absorbing structure 100, making it difficult to achieve sound absorption and noise reduction in the target direction through the reciprocity principle. Even with perpendicular incident conditions, it is difficult to achieve a good sound absorption effect. Figure 4 As shown, when a micro-perforated plate is used as the sound wave absorbing material, the transmittance of the micro-perforated plate under perpendicular incidence remains approximately 0.3. Similarly, if the absorption angle is 90°, the sound wave absorbing material is positioned perpendicular to the sound wave incident surface of the sound wave absorbing structure 100. In this case, the incident sound wave can pass directly through the sound wave absorbing structure 100 under perpendicular incidence, making it difficult to achieve sound absorption and noise reduction. Furthermore, the absorption angle should be greater than or equal to 20° and less than 90°. By controlling the absorption angle to meet the above range, it is beneficial to ensure the sound absorption performance of the sound wave absorbing structure 100 in practical applications, and also beneficial to improve the structural strength of the sound wave absorbing structure 100. Figure 5 Taking Figure (a) as an example, α represents the angle complementary to the first tilt angle β. It can be seen that the high absorption incident angle θ iIt will increase as α increases, until α is about 70°, so the limit value of the absorption tilt angle is about 20°.

[0084] In the process of preparing the sound wave absorbing structure 100, once the absorption tilt angle is determined, the first tilt angle β of the sound wave absorbing material can be set within the range of the absorption tilt angle plus or minus a preset angle, thereby realizing the sound absorption and noise reduction of the sound wave absorbing structure 100 in the target direction.

[0085] In some embodiments, the thickness t of the sound-absorbing material satisfies t≤ω / 5. This allows the thickness of the sound-absorbing material to be much smaller than the spacing, so that when a sound wave is incident along a direction parallel to the surface of the sound-absorbing material, each sound-absorbing material exerts almost no influence on the sound wave. Furthermore, based on the reciprocity principle, the sound absorption effect of the sound-absorbing structure 100 can be further guaranteed.

[0086] In some embodiments, the operating frequency f of the acoustic wave absorption structure 100 is... w The frequency f of the sound wave absorbing structure 100 is negatively correlated with the distance ω between two adjacent sound wave absorbing materials. In other words, the smaller the distance ω between two adjacent sound wave absorbing materials, the lower the operating frequency f of the sound wave absorbing structure 100. w The higher the value, the better ω can be for the required operating frequency f. w Adjustments will be made.

[0087] The following will refer to Figures 4-9 Further description of specific embodiments that reflect the inventive concept of this application.

[0088] In this specific embodiment, a microperforated plate (MPP) with high absorption rate is used as the sound wave absorbing material. The distance between two adjacent microperforated plates is greater than the thickness of the microperforated plate and less than the wavelength of the incident sound wave in air. The perforation diameter of the MPP is 0.1 mm, the plate thickness is 1 mm, and the porosity is 10%.

[0089] Figure 4 The diagram shows the reflectivity, transmittance, and absorptivity of the MPP in this embodiment under perpendicular sound wave incidence as a function of frequency. The relationship between reflectivity, transmittance, and absorptivity can be expressed as the sum of these three values ​​approaching 1. It can be seen that the absorptivity of the MPP is approximately 45%. However, due to... Figure 5 and Figure 6 As can be seen, when the MPPs are tilted at a certain angle to form an array, that is, to form the sound wave absorption structure 100, their absorption performance will be greatly improved. The thickness H of the sound wave absorption structure 100 is 7cm, and the distance between two adjacent MPPs is 3cm.

[0090] like Figure 5As shown in Figure (a), when a 4000 Hz sound wave is incident, and the incident angle of the sound wave is the complementary angle of the first tilt angle (i.e., the sound wave is incident in a direction parallel to the MPP surface), the absorption rate A is almost 0 (shown by the white dashed line), meaning that almost all the sound wave energy passes through the sound wave absorption structure 100. On the other hand, when the incident angle of the sound wave and the complementary angle of the first tilt angle are antisymmetric (i.e., the second tilt angle of the sound wave is symmetrical to the first tilt angle about a preset axis), the absorption rate A is quite high (generally greater than or equal to 0.9, shown by the black solid line). Figure 5 As shown in Figure (b), with an incident sound wave of 1000Hz to 6000Hz and a first tilt angle of 45° for the MPP, and controlling the distance between two adjacent MPPs to be less than the wavelength of the incident sound wave, it can be seen that within the range of incident angles less than or equal to 70°, the reflection is symmetrical with respect to the incident angle and is quite low (basically less than or equal to 0.1, shown by the white solid line). Furthermore, when the incident angle is 45°, zero reflection occurs. Figure 5 As shown in Figure (c), with the same settings as in Figure (b), the absorption of the sound wave absorbing structure 100 at an incident angle of ±45° is antisymmetric. That is, in the wide frequency range, there is basically no absorption when the incident angle of the sound wave is 45°, but when the incident angle of the sound wave is -45°, complete absorption of greater than or equal to 0.9 can occur. Thus, the sound wave absorbing structure 100 has asymmetrical sound absorption characteristics and can achieve sound absorption and noise reduction in the target direction.

[0091] Figure 6 Figure (a) shows the simulated sound field distribution of the sound wave absorbing structure 100 with a first tilt angle of 45° when the sound wave is incident at ±45°. It can be seen that the reflection phenomenon is eliminated in both cases, and near-perfect absorption can be observed when the sound wave is incident at -45°. Figure 6 Figure (b) shows the simulated sound field distribution of the sound wave absorbing structure 100 under a point sound source. It can be seen that the reflection is still quite low, while the transmission exhibits a significant angular asymmetry. Based on this characteristic, this specific embodiment can be used for... Figure 7 The fabrication of the superstructure venetian blind shown can provide a quiet area on one side while enabling normal sound transmission on the other side, which has important application value in some specific scenarios.

[0092] The following will refer to Figure 8 and Figure 9 To conduct relevant experimental verification of the above-mentioned superstructure venetian blinds.

[0093] exist Figure 8 and Figure 9 In the experiments, steel MPPs with periodically arranged triangular cone holes were used. Under vertical incidence, their absorption rate at the working frequency was about 30%.

[0094] The experimental architecture of the Gaussian sound beam is composed of Figure 8 Figure (a) shows two measurement areas on the xy plane, representing the reflection and transmission sides, respectively. These areas are represented by gray rectangular regions, each measuring 32 x 30 cm. 2 The image shows a photograph of the actual sample, 3 cm away from the sample. The MPP tilt angle (i.e., the first tilt angle β) is 45°, and the spacing ω is 3 cm. To generate a quasi-Gaussian sound beam, a loudspeaker array with parabolic mirrors was constructed. The microphone was then mounted on a moving stage to scan the sound field distribution in 10 mm steps. The experiment was conducted in an anechoic chamber to minimize reflections and noise.

[0095] Figure 8 Figure (b) shows the reflectivity, transmittance, and absorptivity as a function of frequency when sound waves are incident at ±45° on the metamorphic louver sample. It can be seen that the reflectivity is quite low when the sound waves are incident at ±45°, while the transmittance and absorptivity exhibit an asymmetry. Specifically, when the sound waves are incident at 45°, the transmittance is quite high, with virtually no absorption; however, when the sound waves are incident at -45°, the absorption of the MPP leads to a decrease in transmittance, with an absorptivity of approximately 60%. Optionally, the absorptivity can be further improved by using MPPs with higher absorptivity or by increasing the thickness of the sound wave absorbing structure. It is understood that when the thickness of the sound wave absorbing structure increases, the sound waves travel a longer distance within the structure, allowing the sound energy to be more fully dissipated by the MPP. Additionally, some experimental errors may be caused by inaccuracies in sample preparation and defects in the Gaussian beam.

[0096] Figure 8 Figure (c) shows the transmitted sound field distribution when sound waves of different frequencies are incident at 45° on the metamorphic louver sample. Figure 8 Figure (d) shows the reflected sound field distribution when sound waves of different frequencies are incident at -45° on the metamorphic louver sample. It can be seen that at 3000Hz, 4000Hz, and 5000Hz, when the sound waves are incident at 45°, almost all of the sound waves are transmitted, and the reflection is almost zero, indicating that the sound absorption structure has ultra-wideband zero-reflection characteristics protected by the reciprocity principle. However, when the sound waves are incident at -45°, the sound absorption structure exhibits better sound absorption at different frequencies.

[0097] The experimental architecture of the point sound source consists of Figure 9 Figure (a) shows that the measurement area, marked by the black box in the figure, measures 40 x 20 cm. 2 The distance between the measurement area and the sound wave absorbing structure is 2cm, and the distance between the loudspeaker and the sound wave absorbing structure is 2cm. Figure 9Figure (b) shows the transmitted sound field distribution of the point source in the sample without the superstructure louvers (top) and the sample with the superstructure louvers (bottom). It can be seen that the left half of the transmitted sound field exhibits greater absorption, while the right half of the transmitted sound field exhibits greater transmission.

[0098] In summary, the aforementioned metamorphic louvers exhibit asymmetrical sound absorption characteristics (i.e., significant angular asymmetry) under the incidence of sound waves from different sound sources. In other words, the aforementioned metamorphic louvers can absorb sound waves in the target direction while transmitting sound waves in a direction symmetrical about the normal to the target direction.

[0099] In some embodiments, by adjusting the boundary conditions, both the reciprocity principle and the complex resonance principle can be introduced, thereby achieving ultra-wideband omnidirectional sound absorption performance. Specifically, such as Figure 10 As shown in Figure (a), the sound wave absorbing material (MPP) includes a first end near the incident side of the sound wave and a second end near the emitting side of the sound wave. The sound wave absorbing structure also includes a first rigid boundary disposed near the second end, and at least a portion of the first rigid boundary extends in a direction parallel to the preset axis. In this way, a first type of omnidirectional sound wave absorbing structure 200 can be formed. Due to the addition of the first rigid boundary, the transmitted sound wave will be reflected back to the sound wave absorbing structure and continue to be dissipated by the sound wave absorbing material, which is beneficial to achieving an omnidirectional sound absorption effect.

[0100] In some embodiments, at least a portion of the second end of the acoustic wave absorbing material is disposed in contact with the first rigid boundary. By directly contacting the first rigid boundary with the second end, it is beneficial to reduce the thickness of the acoustic wave absorbing structure, making the acoustic wave absorbing structure thinner.

[0101] In some embodiments, such as Figure 11 As shown in Figure (a), the acoustic absorbing structure further includes a second rigid boundary intersecting the first rigid boundary or an extension of the first rigid boundary, and at least a portion of the second rigid boundary is located on the side of the first rigid boundary closer to the acoustic absorbing material. Thus, a second type of omnidirectional acoustic absorbing structure 300 can be formed. Due to the addition of the first and second rigid boundaries, complex resonances can be supported, thereby further enhancing the sound absorption effect of the omnidirectional acoustic absorbing structure. Optionally, a gap exists between the second rigid boundary and the acoustic absorbing material, which is beneficial for further enhancing sound dissipation.

[0102] In some embodiments, continue to refer to Figure 11Figure (a) shows that multiple second rigid boundaries are arranged circumferentially along the first rigid boundary. These multiple second rigid boundaries, together with the first rigid boundary, enclose a cavity that opens towards the incident side of the sound wave to accommodate multiple sound-absorbing materials. This arrangement facilitates the formation of a three-dimensional omnidirectional sound absorber, allowing the sound waves to be absorbed more fully by the sound-absorbing materials, thereby further improving the sound absorption performance.

[0103] In some embodiments, the length of the plurality of acoustic absorbing materials in a direction perpendicular to a predetermined axis is greater than or equal to a response length, which is determined at least based on the bulk modulus of air, the effective bulk modulus of the plurality of acoustic absorbing materials in the static limit, and the wavelength of the incident sound wave in air. Specifically, the material response function of the incident sound wave must satisfy the causality principle, which leads to an inequality relating a given absorption spectrum to the sample thickness d:

[0104]

[0105] Where λ and A(λ) represent the wavelength and absorption coefficient of the sound wave in the air, respectively, the absorption coefficient being a function of the wavelength, and B0 being the bulk modulus of air. eff This represents the effective bulk modulus of multiple acoustic absorbing materials under the static limit, with a response length of... Based on the above relationship, the thickness of the sound wave absorbing structure can be reduced as much as possible while satisfying the causality law. In other words, the thickness of the sound wave absorbing structure can be made consistent with the response length, thereby achieving the thinning of the sound wave absorbing structure while satisfying the causality law.

[0106] In some embodiments, the sound wave absorbing structure further includes a first adjustment mechanism coupled to a plurality of sound wave absorbing materials for adjusting a first tilt angle; and / or a second adjustment mechanism coupled to a plurality of sound wave absorbing materials for adjusting the spacing between two adjacent sound wave absorbing materials. The first adjustment mechanism allows adjustment of the first tilt angle of the sound wave absorbing materials, thereby facilitating the adjustment of the first tilt angle to the corresponding absorption tilt angle based on the second tilt angle of the incident sound wave, achieving a better sound absorption effect. The second adjustment mechanism allows adjustment of the spacing between two adjacent sound wave absorbing materials, thereby facilitating the widening of the operating frequency range of the sound wave absorbing structure and meeting the application requirements of higher operating frequencies. For example, the first adjustment mechanism can achieve adjustment of the first tilt angle by connecting to the sound wave absorbing materials via a pivoting structure or a motor. For example, the second adjustment mechanism can achieve adjustment of the spacing by connecting to the sound wave absorbing materials via a thread, a lead screw, or a motor.

[0107] The following will refer to Figures 10-12 Further description of specific embodiments that reflect the inventive concept of this application.

[0108] like Figure 10As shown in Figure (a), the bottom of the first type of omnidirectional acoustic wave absorbing structure 200 (Case 1) changes from an open boundary to a rigid boundary. The relevant parameters are: the complementary angle α of the first tilt angle is 60°, thus the first tilt angle β is 30°; the spacing ω between two adjacent acoustic wave absorbing materials (MPP) is 1 cm; the length D of the first rigid boundary is 10 cm; the thickness of the first rigid boundary is 2 mm; the thickness H of the acoustic wave absorbing structure is 10 cm; and the periodic boundary represents the infinitely far boundary in the simulation. Among them, the parameters of the MPP are: aperture (diameter) of 0.2 mm, plate thickness of 0.1 mm, and porosity of 2%. Figure 10 Figure (b) shows the absorptivity of the first-type omnidirectional acoustic wave absorbing structure 200 as a function of the incident angle and operating frequency. It can be seen that the absorptivity of the acoustic wave is symmetrical about the incident angle and is significantly improved; furthermore, almost |θ... i Sound waves incident at angles ≤ 75° can achieve high absorption rates (A > 0.9) and cover a wide operating frequency range. For example, at |θ i Within the range of ≤60°, sound waves from 800Hz to 16800Hz can achieve a high absorption rate.

[0109] like Figure 11 As shown in Figure (a), the second type of omnidirectional sound wave absorbing structure 300 (Case 2) also has rigid boundaries (i.e., second rigid boundaries) on both the left and right sides of the first type of omnidirectional sound wave absorbing structure 200. At this time, sound waves can form complex resonances within the sound wave absorbing structure, which is beneficial to further improve the absorption rate. In addition, an opening with a distance of s = 5 mm is provided on the left side of the second type of omnidirectional sound wave absorbing structure 300 to enhance sound dissipation. Figure 11 Figure (b) shows the absorption rate versus frequency curves of Case 1, Case 2, and the micro-perforated plate under perpendicular sound wave incidence, where the back cavity depth corresponding to the micro-perforated plate is 9.8 cm (the total thickness is 10 cm). It can be seen that Case 2 exhibits significantly better sound absorption performance compared to the other two. To visually illustrate the complex resonance supported by Case 2, Figure 11 Figure (c) shows the normalized acoustic intensity (|P|) at 330 Hz for Case 1 and Case 2. 2 The sound intensity in Case 1 (M) is uniformly accumulated along the propagation direction, indicating that the dissipation of the micro-perforated plate itself plays a dominant role. However, due to the constraint of the second rigid boundary on both sides, the highest intensity in Case 2 (Q) occurs in the lower left corner, showing a complex resonance that contributes to the highest sound absorption. Furthermore, the curvature of the velocity flow in Case 2 (Q) (indicated by the white arrow) indicates that the coupling between the micro-perforated plates is stronger than in Case 1 (M). It is understandable that stronger coupling results in higher and smoother overall absorption of the sound wave absorbing structure, while weaker coupling leads to a poorer overall absorption effect.

[0110] Figure 12 Figure (a) is a schematic diagram of the structure of the three-dimensional omnidirectional sound absorber proposed in Case 2, wherein, This represents the angle of incidence of the sound wave in the xz plane. This represents the angle of incidence of the sound wave in the yz plane. The relevant parameters of this three-dimensional omnidirectional sound absorber can be found in Case 2, and will not be repeated here. Optionally, the bottom surface of the three-dimensional omnidirectional sound absorber is square. For clarity, the front panel of this three-dimensional omnidirectional sound absorber is rendered transparent to observe internal details. Figure 12 Figure (b) shows the absorptivity of the three-dimensional omnidirectional sound absorber as a function of the incident angle and operating frequency when the sound wave is incident in the xz plane. It can be seen that the three-dimensional omnidirectional sound absorber exhibits omnidirectional and ultra-wideband absorption performance in the xz plane. For example, in... At that time, the absorption rate of sound waves reached 90% at a frequency of 370 Hz, and the average absorption rate in the frequency band of 370 Hz to 12000 Hz was 92.4%. It is worth noting that... When the second tilt angle is symmetrical to the first tilt angle about the preset axis, the average absorption rate of the sound wave in the frequency band of 370Hz to 12000Hz can reach 97.1%. Figure 12 Figure (c) shows the functional relationship between the absorptivity of the three-dimensional omnidirectional sound absorber and the incident angle and operating frequency when the sound wave is incident in the yz plane. It can be seen that although the sound absorption effect of the three-dimensional omnidirectional sound absorber is slightly inferior to that when the sound wave is incident in the xz plane, it still exhibits omnidirectional and ultra-wideband sound absorption performance. On the other hand, by substituting the parameters of the three-dimensional omnidirectional sound absorber into the aforementioned formula (1), the theoretical minimum value d of the thickness of the three-dimensional omnidirectional sound absorber can be obtained. min =9.52cm, which is close to the actual thickness of the three-dimensional omnidirectional sound absorber (H=10cm), indicating that the three-dimensional omnidirectional sound absorber has been made as thin as possible.

[0111] The following will refer to Figure 13 To verify the above-mentioned three-dimensional omnidirectional sound absorber through relevant experiments.

[0112] like Figure 13 As shown in Figure (a), the impedance tube method was used in the experiment. Figure 13 Figure (b) shows a photograph of the actual sample (sample 1) made using steel plate etching technology. A smaller sample (sample 2) was also made to measure the sound absorption performance at a higher frequency. Figure 13Figure (c) shows the structure of sample 2. The relevant parameters of sample 2 are: the complementary angle α of the first tilt angle is 60°, resulting in a first tilt angle β of 30°; the spacing ω between two adjacent acoustic wave absorbing materials (MPPs) is 1 cm; the bottom surface of sample 2 is square; the length D of the first rigid boundary is 5 cm; the length D of the second rigid boundary in the direction perpendicular to the preset axis is 5 cm, and the spacing s between the second rigid boundary and the acoustic wave absorbing material is 3 mm; the thickness H of sample 2 is 10 cm; the parameters of the MPPs can be found in Case 1. The experimental setup includes two square impedance tubes with side lengths of 10 cm and 5 cm, respectively. Their cross-sectional dimensions represent cutoff frequencies of approximately 800 Hz and 3300 Hz, respectively. Above these frequencies, the measurement results become inaccurate. Figure 13 The large image in Figure (d) shows the absorption rate curves of Sample 1 and Sample 2 under simulation, where Sample 1 (simulation) is represented by a solid circle and Sample 2 (simulation) by a solid square. The inset in the large image shows both the absorption rate curves of Sample 1 and Sample 2 in the gray area of ​​the large image and the absorption rate curves of Sample 1 and Sample 2 under experimental measurement, where Sample 1 (experimental) is represented by a hollow circle and Sample 2 (experimental) by a hollow square. It can be seen that the experimental measurement results are very close to the simulation results, and Sample 1 and Sample 2 can even achieve high sound absorption in the simulation frequency range of 10000Hz and above. In addition, for comparison, the inset also includes the absorption rate curves of an MPP with a back cavity depth of 9.8cm (total thickness 10cm) under simulation and experimental measurement, where MPP (simulation) is represented by a solid triangle and MPP (experimental) by a hollow triangle. Clearly, compared with traditional MPPs, the three-dimensional omnidirectional sound absorber of this application exhibits superior sound absorption performance.

[0113] This application also provides a method for preparing an acoustic wave absorbing structure.

[0114] In one embodiment, the preparation method includes the following steps:

[0115] S100. Obtain multiple sound wave absorbing materials spaced apart along a preset axis; wherein, along the preset axis, the distance ω between two adjacent sound wave absorbing materials satisfies: t < ω < λ, where t represents the thickness of the sound wave absorbing material and λ represents the wavelength of the incident sound wave.

[0116] For example, the aforementioned sound wave absorbing material includes at least one of micro-perforated plates, textile sound-absorbing materials, and foamed metals.

[0117] S200. Obtain the absorption tilt angle of the sound wave absorbing material; wherein, each sound wave absorbing material has a first tilt angle relative to a preset axis, and the sound wave incident on each sound wave absorbing material has a second tilt angle relative to the preset axis. When the first tilt angle and the second tilt angle are symmetrical about the preset axis, the first tilt angle is the absorption tilt angle of the sound wave absorbing material.

[0118] For example, when the first tilt angle and the second tilt angle are symmetrical about a preset axis, wideband impedance matching characteristics can be achieved based on the reciprocity principle.

[0119] S300, at least a portion of the sound wave absorbing material is tilted relative to the preset axis within a range of its absorption tilt angle plus or minus a preset angle.

[0120] For example, the upper limit of the preset angle can be 15°, and the preset angle can be 3°, 5°, 8°, 10°, or 15°.

[0121] The above-described method for fabricating a sound wave absorbing structure involves calculating the absorption angle of the sound wave absorbing material based on the second tilt angle of the incident sound wave relative to a preset axis, and then setting the first tilt angle of the sound wave absorbing material relative to the preset axis based on the absorption tilt angle, thereby obtaining the aforementioned sound wave absorbing structure. This method allows for the fabrication of a sound-absorbing structure designed based on the propagation direction of the incident sound wave, achieving directional sound absorption.

[0122] In some embodiments, the preparation method further includes:

[0123] S10. Obtain the operating frequency f of the acoustic wave absorption structure. w ;

[0124] S20, according to the working frequency f w Adjust the spacing ω between two adjacent sound-absorbing materials; where f w It is negatively correlated with ω.

[0125] In this way, the spacing between two adjacent sound-absorbing materials can be adjusted according to the frequency of the incident sound wave, thereby helping to meet customized sound absorption requirements. Optionally, these two steps can be arranged before or after step S100. This application does not impose any restrictions on this.

[0126] In some embodiments, the sound-absorbing material includes a first end near the incident side of the sound wave and a second end near the emitting side of the sound wave, and the preparation method further includes:

[0127] S400, A first rigid boundary is provided near the second end; wherein at least a portion of the first rigid boundary extends in a direction parallel to the preset axis.

[0128] In this way, the transmitted sound waves will be reflected back to the sound wave absorbing structure by the first rigid boundary and continue to be dissipated by the sound wave absorbing material, which is beneficial to achieving an omnidirectional sound absorption effect.

[0129] Furthermore, the preparation method also includes:

[0130] S500, a second rigid boundary is provided that intersects with the first rigid boundary or the extension of the first rigid boundary; wherein at least a portion of the second rigid boundary is located on the side of the first rigid boundary closer to the sound wave absorbing material.

[0131] In this way, the transmitted sound waves will be reflected by both the first and second rigid boundaries, thus forming a complex resonance within the sound wave absorption structure, which is beneficial to further improve the sound absorption effect of the omnidirectional sound wave absorption structure.

[0132] This application also provides a sound transmission device.

[0133] In one embodiment, the sound transmission device includes: an incident surface and an exit surface of a sound wave disposed opposite to each other; and a sound absorption structure as described in the preceding embodiment disposed between the incident surface and the exit surface of the sound wave; the sound transmission device is adapted to transmit sound waves incident along a first direction and shield sound waves incident along a second direction, wherein the first direction is parallel to the tilt direction of the sound absorption material, and the first direction and the second direction are symmetrical about a predetermined axis.

[0134] For example, the sound transmission device can be used in directional communication devices and encrypted communication devices.

[0135] The aforementioned sound transmission device, through the sound wave absorption structure described in the previous embodiment, can achieve sound wave transmission in the first direction while shielding sound waves in the second direction, thus achieving an asymmetrical sound transmission effect.

[0136] This application also provides a device comprising: a receiving cavity; a target sound source disposed in the receiving cavity; and a sound wave absorbing structure as described above for absorbing sound waves emitted by the target sound source.

[0137] Some devices may generate significant noise during operation. After locating the noise source, sound wave absorption structures, as described above, can be placed near the noise source or along the noise transmission path to absorb sound and reduce noise, thereby improving the noise control performance of the device.

[0138] It should be noted that the numbers used to describe and claim certain embodiments of this application, representing quantities or properties, should be understood to be modified in some cases by the terms "approximately," "about," "approximately," or "essentially." For example, unless otherwise stated, "approximately," "about," "approximately," or "essentially" can indicate a variation of ±20% of the value they describe. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed according to the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this application are approximate values, in specific embodiments, such numerical values ​​are set as precisely as feasible.

[0139] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of the present invention and do not limit the scope of protection of this patent.

Claims

1. A sound wave absorbing structure, characterized in that, include: A plurality of sound wave absorbing materials are spaced apart along a preset axis. The sound wave absorbing materials include a first end near the incident side of the sound wave and a second end near the emitting side of the sound wave. The sound wave absorbing structure also includes a first rigid boundary near the second end, and at least a portion of the first rigid boundary extends in a direction parallel to the preset axis. and, The spacing between two adjacent sound-absorbing materials along the extension direction of the preset axis satisfy: ,in, This indicates the thickness of the sound wave absorbing material. Indicates the wavelength of the incident sound wave; and, Each of the sound wave absorbing materials has a first tilt angle relative to the preset axis, and the sound wave incident on each of the sound wave absorbing materials has a second tilt angle relative to the preset axis. When the first tilt angle and the second tilt angle are symmetrical about the preset axis, the first tilt angle is the absorption tilt angle of the sound wave absorbing material. in, At least a portion of the sound-absorbing material is configured to be tilted relative to the preset axis within a range of its absorption tilt angle plus or minus a preset angle.

2. The acoustic wave absorbing structure according to claim 1, characterized in that, Each of the aforementioned acoustic absorbing materials is configured to be tilted relative to the preset axis within a range of its absorption tilt angle plus or minus a preset angle.

3. The acoustic wave absorption structure according to claim 1, characterized in that, The absorption tilt angle is greater than 0° and less than 90°.

4. The acoustic wave absorbing structure according to claim 3, characterized in that, The absorption tilt angle is greater than or equal to 20° and less than 90°.

5. The acoustic wave absorbing structure according to claim 1, characterized in that, The preset angle is less than or equal to 15°.

6. The acoustic wave absorbing structure according to claim 1, characterized in that, 。 7. The acoustic wave absorbing structure according to claim 1, characterized in that, The operating frequency of the sound wave absorption structure The spacing between two adjacent acoustic absorbing materials Negative correlation.

8. The acoustic wave absorbing structure according to claim 1, characterized in that, The sound wave absorbing material includes at least one of micro-perforated plates, textile sound-absorbing materials, and foamed metals.

9. The acoustic wave absorbing structure according to claim 1, characterized in that, At least a portion of the second end of the acoustic wave absorbing material is disposed in contact with the first rigid boundary.

10. The acoustic wave absorbing structure according to claim 1, characterized in that, The acoustic wave absorbing structure further includes a second rigid boundary that intersects the first rigid boundary or the extension of the first rigid boundary, and at least a portion of the second rigid boundary is located on the side of the first rigid boundary closer to the acoustic wave absorbing material.

11. The acoustic wave absorbing structure according to claim 10, characterized in that, A plurality of second rigid boundaries are provided circumferentially along the first rigid boundary, and the plurality of second rigid boundaries together with the first rigid boundary form a cavity for accommodating the plurality of sound wave absorbing materials, which opens toward the incident side of the sound wave.

12. The acoustic wave absorbing structure according to any one of claims 1 to 11, characterized in that, The length of the plurality of acoustic wave absorbing materials in the direction perpendicular to the preset axis is greater than or equal to a response length, which is determined at least based on the bulk modulus of air, the effective bulk modulus of the plurality of acoustic wave absorbing materials under the static limit, and the wavelength of the incident sound wave in air.

13. The acoustic wave absorbing structure according to claim 1, characterized in that, Also includes: A first adjustment mechanism coupled to the plurality of acoustic wave absorbing materials for adjusting the first tilt angle; And / or, A second adjustment mechanism coupled to the plurality of acoustic wave absorbing materials for adjusting the spacing.

14. A method for preparing an acoustic wave absorbing structure, characterized in that, include: A plurality of sound wave absorbing materials are obtained and spaced apart along a preset axis; wherein, each sound wave absorbing material includes a first end near the incident side of the sound wave and a second end near the emitting side of the sound wave, and the spacing between two adjacent sound wave absorbing materials along the preset axis is... satisfy: , This indicates the thickness of the sound wave absorbing material. Indicates the wavelength of the incident sound wave; A first rigid boundary is provided near the second end; wherein at least a portion of the first rigid boundary extends in a direction parallel to the preset axis; Obtain the absorption tilt angle of the sound wave absorbing material; wherein, each of the sound wave absorbing materials has a first tilt angle relative to the preset axis, and the sound wave incident on each of the sound wave absorbing materials has a second tilt angle relative to the preset axis. When the first tilt angle and the second tilt angle are symmetrical about the preset axis, the first tilt angle is the absorption tilt angle of the sound wave absorbing material. At least a portion of the sound wave absorbing material is tilted relative to the preset axis within a range of its absorption tilt angle plus or minus a preset angle.

15. The preparation method according to claim 14, characterized in that, Also includes: Obtain the operating frequency of the sound wave absorption structure ; According to the operating frequency Adjust the spacing between two adjacent sound-absorbing materials ;in, and Negative correlation.

16. The preparation method according to claim 14, characterized in that, Also includes: A second rigid boundary is provided that intersects the first rigid boundary or an extension of the first rigid boundary; wherein at least a portion of the second rigid boundary is located on the side of the first rigid boundary closer to the sound wave absorbing material.

17. A device, characterized in that, include: Receptacle; The target sound source is located in the receiving cavity; and, The sound wave absorbing structure as described in any one of claims 1 to 13 for absorbing the sound waves emitted by the target sound source.

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