Passive superstructure sound absorption and noise reduction earmuff and method based on acoustic capillary effect

Abstract

The invention discloses a passive superstructure sound absorption and noise reduction earmuff based on an acoustic capillary effect and a method. The passive superstructure sound absorption and noise reduction earmuff is formed by regularly arranging and combining a plurality of F-P resonant cavity superstructures (1) with different working frequencies in three different areas of an ear shell (2), an ear pad (3) and a head band (4), the resonant cavities are tightly arranged, and some longer resonant cavities are folded to reduce the occupation of the structural volume. The passive superstructure sound absorption and noise reduction earmuff design method is provided by comprehensively utilizing the acoustic capillary effect, the siphonic effect and the F-P resonance sound absorption mechanism, and compared with a traditional device, the passive superstructure sound absorption and noise reduction earmuff design method can adapt to a smaller use space while exerting the passive noise reduction advantage.

Description

Technical Field

[0001] The invention belongs to the technical field of sound absorption, and in particular relates to a passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect and a method thereof. Background Art

[0002] The auditory system is an important component of the environmental perception of humans and other animals, and is also one of the main means of interacting with the external environment. When the human body is in a high noise environment of more than 80 decibels for a long time, hearing will be damaged. If the noise reaches more than 120 decibels, the human hearing organs and internal organs will be irreversibly damaged. Although traditional acoustic protection technology, including traditional porous sound-absorbing materials and active noise reduction technology, guarantees the sound absorption effect under certain conditions, it is not applicable when there are space limitations and lacks designability. Active noise reduction technology has limited effect on high-frequency noise with very short wavelengths.

[0003] Traditional sound-absorbing materials can be divided into two categories according to their sound absorption mechanisms: resonant sound-absorbing materials and porous sound-absorbing materials. Resonant sound-absorbing materials are mainly based on the viscous loss mechanism. When the structure resonates under the excitation of sound waves, the wall viscous damping plays a major role at this time, and the sound absorption effect is the best; however, due to the resonance characteristics, its bandwidth is narrow, and it can only have good sound absorption performance near the resonance frequency. Porous sound-absorbing materials have both viscous loss mechanism and thermal conduction loss mechanism. The material does not have obvious resonance characteristics and has a wide sound absorption bandwidth that can cover the entire high-frequency range. Traditional porous sound-absorbing materials, such as sponges and foams, require a large thickness to achieve noise reduction and are not suitable for confined small spaces.

[0004] At present, active noise reduction technology is the mainstream technology for ear noise control. Its working principle is to output sound waves with opposite phases through electrical signal feedback to offset the incoming noise to achieve the effect of noise suppression. Active noise reduction technology has a good noise reduction effect on low-frequency noise, but for high-frequency noise with a very short wavelength, it is difficult for the electrical signal to accurately and in real time generate an active signal with a phase difference of 0.5 from the noise signal to offset it. When there is a phase offset, it will even enhance the noise. In addition, the active noise reduction system requires a certain amount of time to process the signal and generate reverse sound waves, which causes delays in its operation and affects the user experience. Therefore, there is an urgent need to develop passive noise reduction earmuffs that break through the restrictive relationship between broadband noise reduction design and small space size, while achieving timely response. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of existing foam porous materials and active noise reduction technologies, and to provide a passive superstructure sound absorption and noise reduction earmuff and method based on acoustic capillary effect. An FP resonance cavity structure based on acoustic capillary effect and siphon effect is introduced into the design of the earmuff to achieve passive noise reduction with wide frequency bandwidth and good sound absorption effect.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect, which is composed of a plurality of FP resonance cavity superstructures with different working frequencies arranged and combined in three different areas: the ear shell, the ear pad and the headband; the resonance cavities are closely arranged, and some of the resonance cavities are folded to reduce the volume occupied by the structure.

[0007] A further improvement of the present invention is that a high sound absorption coefficient is ensured by the acoustic capillary effect of a relatively thin FP resonant cavity superstructure.

[0008] A further improvement of the present invention is that broadband passive sound absorption and noise reduction is achieved by combining FP resonant cavity superstructures with different gradient lengths.

[0009] A further improvement of the present invention is that the sound absorption and noise reduction in the low frequency range is achieved through the gradient parameter design of the FP resonance cavity superstructure, and the high-order sound absorption performance of the FP resonance cavity superstructure is combined to achieve medium and high frequency sound absorption and noise reduction, thereby achieving low, medium and high broadband coverage of the sound absorption frequency band.

[0010] A further improvement of the present invention is that the earmuff uses an FP resonance cavity superstructure, and the impedance matching characteristics are optimized by adjusting the cross-sectional area and length of the resonance cavity, so as to achieve the requirements of both sound absorption bandwidth and sound absorption efficiency.

[0011] A further improvement of the present invention is that, through the arrangement of the FP resonance cavity superstructure on the ear shell, ear pad and headband, full coverage of the sound space around the ear is achieved, and all-directional sound waves are passively weakened through the structural resonance sound absorption effect, thereby achieving a multi-directional stereo sound absorption effect.

[0012] A further improvement of the present invention is that the earmuff adopts a split structure to maximize the use of the three areas of the earmuff, namely the ear shell, the ear pad and the headband, and the FP resonance cavity superstructure is adapted to the narrow space by folding.

[0013] A further improvement of the present invention is that the device utilizes a FP-type multi-order broadband sound-absorbing superstructure, which is simple and regular and has good structural rigidity and load-bearing capacity.

[0014] A further improvement of the present invention is that the FP resonance cavity is a curled channel with a narrow cross-section, different lengths correspond to different frequency groups, and resonance loss occurs after the sound energy enters, and broadband sound absorption is achieved through a combination of different lengths.

[0015] A method for using a passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect. When working, noise enters from the resonance cavity openings at the ear shell and the ear pad. The acoustic capillary effect and siphon effect brought by the FP resonance cavity superstructure gradually weaken the noise energy, achieving a broadband passive sound absorption effect.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: 1. Sound absorption is achieved through the combination of FP resonant cavity superstructures with different gradient lengths. The combination of resonant cavities can be customized according to the working frequency range to achieve broadband noise reduction and sound absorption in different frequency domains, which is widely used in various noise environments in production and life; 2. By adjusting the cross-sectional area and length of the FP resonant cavity superstructure and optimizing the impedance matching characteristics, the requirements of both sound absorption bandwidth and sound absorption efficiency can be achieved; 3. The FP type multi-order broadband sound absorption superstructure used has a simple and regular shape. The structure is simple and regular, easy to process, and has good structural rigidity and load-bearing capacity, which is suitable for large-scale engineering applications; 4. Through reasonable arrangement and bending and folding of the FP resonant cavity superstructure, it can adapt to the actual volume requirements under different working conditions and achieve broadband noise reduction and sound absorption in a small area; 5. The acoustic capillary effect of the finer FP resonance cavity superstructure ensures a high sound absorption coefficient, and the excellent high-order sound absorption performance of the FP resonance cavity structure is combined to achieve mid- and high-frequency sound absorption and noise reduction, thereby achieving low, medium and high broadband coverage of the sound absorption frequency band; 6. Broadband passive sound absorption and noise reduction is achieved through the combination of FP resonant cavity superstructures with different gradient lengths; 7. By adopting a split structure, the earmuffs are mainly divided into three areas: ear shell, ear pad and headband, so as to achieve full coverage of the sound space around the ear. The sound waves in all directions are passively weakened through the sound absorption effect of structural resonance, achieving a multi-directional three-dimensional sound absorption effect; 8. Through the passive noise reduction design based on acoustic capillary effect, siphon effect and FP resonance cavity structure, the earmuffs can meet the requirements of small working spaces while having low latency, wide frequency range and excellent sound absorption effects.

[0017] In summary, we designed a passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect, which uses FP-type multi-order broadband sound absorption superstructure based on acoustic capillary effect and siphon effect. Compared with traditional materials, this structure achieves low-frequency broadband sound absorption in the deep subwavelength range. The structure is simple and regular, easy to process, and has good structural stiffness and bearing capacity, and has good potential for practical engineering application. The sound absorption and noise reduction in the low-frequency range is achieved by structural gradient parameter design, and the sound absorption and noise reduction in the medium and high frequency range is achieved by combining the excellent high-order sound absorption performance of the FP resonance cavity structure, thereby achieving low, medium and high broadband coverage of the sound absorption frequency band. By adjusting the cross-sectional area and length of the FP resonance cavity and optimizing the impedance matching characteristics, the requirements of both sound absorption bandwidth and sound absorption efficiency can be achieved. The reasonable arrangement and bending and folding of the FP resonance cavity can improve the space utilization rate and achieve broadband noise reduction and sound absorption in a small area. The earmuffs adopt a split structure, which is mainly divided into three areas: ear shell, ear pad, and headband, to achieve full coverage of the sound space around the ear. The sound waves in all directions are passively weakened through the structural resonance sound absorption effect, achieving a multi-directional three-dimensional sound absorption effect. This passive noise reduction design based on the acoustic capillary effect, siphon effect and FP resonance cavity structure can adapt to smaller usage spaces while taking advantage of passive noise reduction compared to traditional devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The schematic diagram of the structure of the passive superstructure sound absorption and noise reduction earmuffs based on the acoustic capillary effect; Figure 2 It is a schematic diagram of the cross section of the FP resonant cavity; Figure 3 It is the arrangement diagram of FP resonant cavity; Figure 4 Integrated structural diagram for earmuff simulation; Figure 5 This is the simulation result diagram of the earmuff integrated structure; Figure 6 It is the body diagram of the earmuff FP resonance cavity unit; Figure 7 This is the simulation result diagram of the earmuff FP resonance cavity unit. DETAILED DESCRIPTION

[0019] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0020] 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 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0024] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0025] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Example 1 like Figure 1 , Figure 2 As shown, the passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect provided by the present invention is mainly composed of a plurality of FP resonance cavity superstructures 1 with different working frequencies which are regularly arranged and combined in three different areas of the ear shell 2, the ear pad 3 and the headband 4; the resonance cavities are closely arranged, and some longer resonance cavities are folded to reduce the volume occupied by the structure.

[0029] In this embodiment, a high sound absorption coefficient is ensured by the acoustic capillary effect of the thinner FP resonant cavity superstructure 1 .

[0030] In this embodiment, broadband passive sound absorption and noise reduction is achieved by combining FP resonant cavity superstructures 1 with different gradient lengths.

[0031] In this embodiment, the gradient parameter design of the FP resonant cavity superstructure 1 is used to achieve sound absorption and noise reduction in the low-frequency range, and the high-order sound absorption performance of the FP resonant cavity superstructure 1 is combined to achieve mid- and high-frequency sound absorption and noise reduction, thereby achieving low, mid and high broadband coverage of the sound absorption frequency band.

[0032] In this embodiment, the earmuff uses the FP resonant cavity superstructure 1, and optimizes the impedance matching characteristics by adjusting the cross-sectional area and length of the resonant cavity, so as to achieve the requirements of taking into account both the sound absorption bandwidth and the sound absorption efficiency.

[0033] In this embodiment, by arranging the FP resonance cavity superstructure 1 on the ear shell 2, ear pad 3 and headband 4, full coverage of the sound space around the ear is achieved, and all-directional sound waves are passively weakened through the structural resonance sound absorption effect, achieving a multi-directional stereo sound absorption effect.

[0034] In this embodiment, the earmuff adopts a split structure to maximize the use of the three areas of the earmuff, namely the ear shell 2, the ear pad 3 and the headband 4, and the FP resonance cavity superstructure 1 is folded to adapt to the narrow space.

[0035] In this embodiment, the device utilizes the FP type multi-order broadband sound absorbing superstructure 1, which has a simple and regular structure and good structural rigidity and load-bearing capacity.

[0036] In this embodiment, the FP resonance cavity 1 is a curled channel with a narrow cross-section. Different lengths correspond to different frequency groups. Resonance loss occurs after the sound energy enters, and broadband sound absorption is achieved through a combination of different lengths.

[0037] Example 2 The present invention provides a method for using a passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect. When working, noise enters from the resonance cavity openings at the ear shell 2 and the ear pad 3, and the acoustic capillary effect and siphon effect brought by the FP resonance cavity superstructure 1 gradually weaken the noise energy, thereby achieving a broadband passive sound absorption effect.

[0038] Example 3 1. Analysis of sound absorption coefficient The sound absorption coefficient of a sound-absorbing material or structure refers to the ratio of the energy absorbed by it to the total incident energy, represented by the symbol α, that is: (1-1) In general, when the sound wave p i When incident on the sound absorbing material, part of the sound wave will be reflected r , part of the sound wave will be transmitted to the rear t , and part of it is absorbed by the sound absorbing material. Therefore, the total incident sound wave energy consists of three parts, namely: (1-2) The sound absorption coefficient can be obtained from the above formula: (1-3) in is the sound pressure reflection coefficient, which is the ratio of reflection to incident; is the sound pressure projection coefficient, which is the ratio of the projected part to the total incident. In most cases, when the sound-absorbing material is subjected to sound absorption treatment, the back end is regarded as an absolute hard boundary condition, at which time the transmitted energy is zero and the sound absorption coefficient is: (1-4) like Figure 5 , Figure 7 As shown, the vertical axis is the sound absorption coefficient.

[0039] (II) Acoustic siphon effect broadband sound absorption mechanism The most effective way to achieve broadband sound absorption is to increase the number of resonant cavities to obtain multiple different sound absorption peaks. Figure 7 A continuous sound absorption broadband is shown. However, when multiple resonance cavities are used for sound absorption in parallel, in order to achieve 100% sound absorption, a certain resonance cavity is required to absorb all incident energy. At this time, the sound wave will have a phenomenon of concentrated energy flowing to this unit. This phenomenon is called the "acoustic siphon effect". The acoustic siphon effect is caused by the inconsistent acoustic impedance of the surface of the structure. The difference in impedance will produce a sound pressure difference between the two resonance cavities, which will cause the concentrated flow of sound wave particles.

[0040] (III) Analysis of FP resonant cavity structure performance The passive noise reduction earmuffs use the FP resonant cavity structure as the basic subunit, which has multiple sound absorption peaks and can achieve customized sound absorption effects and frequency ranges through different combinations. The superstructure is simple in composition and easy to process, while having good structural rigidity and a certain load-bearing capacity.

[0041] FP structure impedance Z a The cavity impedance Z c and end correction Z e composition: (3-1) Terminal correction impedance Z e It is mainly caused by the end radiation caused by the discontinuous interface area at the opening. Under the action of sound pressure, when the sound wave particles enter the cavity, due to the reduction of area, some particles will flow along the plate surface, resulting in energy loss under the influence of friction; on the other hand, when the sound wave flows out of the cavity, it will form a jet and generate energy loss. In fact, the end impedance has little effect on the sound quality, and it can be expressed as only the form of acoustic resistance, that is, Z e =X e Therefore, the impedance ratio z of the FP structure is s It can be expressed as: (3-2) in is the end-corrected relative acoustic resistivity.

[0042] Here, the sound absorption peak is divided into two parts: peak frequency and sound absorption coefficient. First, according to the impedance matching condition, at the peak frequency, the system resonates and its acoustic reactance should be zero, that is: (3-3) So, we can get: (3-4) Simplified: (3-5) or: (3-6) It can be seen from formula (3-3) that the peak frequency has multiple solutions, which means that the structure has multiple sound absorption peaks. Reasonable arrangement of these FP resonance cavities with different peaks can achieve a broadband sound absorption effect. The peak frequency is determined by the equivalent sound velocity and cavity depth The equivalent sound speed depends on the cross-sectional area of ​​the cavity, so the peak frequency is mainly determined by the cavity depth. The greater the depth, the lower the peak frequency. Therefore, in order to achieve better sound absorption effects in the three frequency bands of low, medium and high, it is necessary to design FP resonance cavities of different lengths. By writing formula (3-5) in the form of (3-6), it can be seen that the cavity depth is 1 / 4 times the wavelength corresponding to the peak frequency, that is, when the wavelength of the sound wave is 4 times the depth of its cavity, the sound absorption peak appears. Obviously, the smaller the cross-sectional area and the greater the depth, the greater the acoustic resistance, and the corresponding sound absorption capacity and peak value will first increase and then decrease. When designing FP superstructure earmuffs, first determine its operating frequency range, and then use formula (3-5) to substitute different cavity depths l0 to calculate the sound absorption peak frequency f corresponding to different depths l, so as to obtain multiple different sound absorption peaks, and obtain a continuous sound absorption broadband through strict coupling between the peaks, as shown in the result. Figure 7 shown.

[0043] After the required FP resonant cavity combination is calculated by the formula, further verification is required, such as Figure 6 As shown, the resonant cavity of all lengths of the combination is modeled, and then a sound absorption simulation experiment is performed to obtain the simulation results as shown in Figure 7 As shown, it can be seen that the combination can achieve a stable sound absorption coefficient of more than 0.7 in the 500-4000Hz range, especially in the 500-800Hz range, the sound absorption coefficient can be close to 1.0. Overall, broadband sound absorption with good sound absorption effect is achieved.

[0044] Get as Figure 7 After the simulation results are in line with expectations, the resonant cavity assembly is embedded in the earmuff, as shown in FIG. Figure 3 As shown, the next step is to carry out the physical experiment. Figure 4 As shown in Figure 1, the model is a collection of all FP resonant cavities in the earmuff. A simulation experiment was also conducted on the model before the actual experiment, and the results are shown in Figure 1. Figure 5 As shown. It can be found that Figure 5 Results and Figure 7Compared with the results, the overall sound absorption coefficient is lower, because the sound absorption coefficient is affected by the number of resonance cavity openings per unit area. The more FP resonance cavities per unit area, the higher the sound absorption coefficient.

[0045] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0046] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect, characterized in that: The invention is composed of a plurality of FP resonant cavity superstructures (1) with different working frequencies arranged and combined in three different areas: the ear shell (2), the ear pad (3) and the headband (4); the resonant cavities are closely arranged, and some of the resonant cavities are folded to reduce the volume occupied by the structure.

2. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: The high sound absorption coefficient is ensured by the acoustic capillary effect of the thin FP resonant cavity superstructure (1).

3. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: Broadband passive sound absorption and noise reduction is achieved by combining FP resonant cavity superstructures (1) with different gradient lengths.

4. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: The gradient parameter design of the FP resonant cavity superstructure (1) is used to achieve sound absorption and noise reduction in the low frequency range, and the high-order sound absorption performance of the FP resonant cavity superstructure (1) is combined to achieve mid- and high-frequency sound absorption and noise reduction, thereby achieving low, mid and high broadband coverage of the sound absorption frequency band.

5. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: The earmuffs use the FP resonant cavity superstructure (1) and optimize the impedance matching characteristics by adjusting the cross-sectional area and length of the resonant cavity to achieve the requirements of both sound absorption bandwidth and sound absorption efficiency.

6. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: By arranging the FP resonance cavity superstructure (1) on the ear shell (2), the ear pad (3) and the headband (4), full coverage of the sound space around the ear is achieved, and sound waves in all directions are passively weakened through the structural resonance sound absorption effect, thereby achieving a multi-directional three-dimensional sound absorption effect.

7. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: The earmuff adopts a split structure to maximize the use of three areas of the earmuff, namely the ear shell (2), the ear pad (3) and the headband (4), and the FP resonance cavity superstructure (1) is folded to adapt to a small space.

8. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: The device utilizes a FP-type multi-order broadband sound-absorbing superstructure (1), which is simple and regular while having good structural stiffness and load-bearing capacity.

9. The passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to claim 1, characterized in that: The FP resonant cavity (1) is a curled channel with a narrow cross-section. Different lengths correspond to different frequency groups. After the sound energy enters, resonance loss occurs. The combination of different lengths achieves broadband sound absorption.

10. A method for using a passive superstructure sound absorption and noise reduction earmuff based on acoustic capillary effect according to any one of claims 1 to 9, characterized in that: When working, noise enters from the resonant cavity openings at the ear shell (2) and the ear pad (3), and the acoustic capillary effect and siphon effect brought about by the FP resonant cavity superstructure (1) gradually weaken the noise energy, thereby achieving a broadband passive sound absorption effect.

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