A resonant unit of a frequency-modulated, ultrathin, multifunctional low-frequency sound-absorbing device and its use

Abstract

The application discloses a resonant unit of a frequency-modulated, ultrathin and multifunctional low-frequency sound-absorbing device and application thereof. The resonant unit is internally provided with a square air resonant cavity which is surrounded by two end faces and four coiled channels which are located between the two end faces and have the same structure. The four coiled channels are centrally symmetrically distributed. The sound channel entrance and the sound channel exit of the coiled channel are communicated by a plurality of transverse serpentine bends and a plurality of longitudinal serpentine bends, and the transverse serpentine bend and the longitudinal serpentine bend have a right-angle bend. The length of the resonant unit reaches 1 / 11 lambda, has the characteristic of deep subwavelength, and the peak value of the sound energy absorption rate can reach more than 0.95. The length of the resonant unit and the sound-absorbing effect in the low-frequency range can be simultaneously ensured, the resonant unit has good sound-absorbing performance in the low-frequency range, and the space occupancy ratio of the resonant unit can reach 15%, so that the space utilization rate can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of noise control, specifically to the resonant unit of a frequency-modulated, ultra-thin, multi-functional low-frequency noise reduction device and its applications. Background Technology

[0002] Noise pollution is the third largest public hazard after air and water pollution. Noise reduction methods mainly focus on blocking the propagation path and reducing vibration at the sound source. Low-frequency noise reduction / insulation technology has wide practical applications in architectural acoustics and mechanical manufacturing, thus its research has always received widespread attention from the scientific and engineering communities. Traditional noise reduction / insulation materials mainly include porous and fibrous materials, as well as micro-perforated plate structures with cavities. The performance of traditional noise reduction / insulation materials strictly follows the mass density law, leading to large side lengths and high densities in the low-frequency range, thus limiting their application range. In recent years, the emergence of acoustic metamaterials, especially acoustic metasurfaces, has provided new ways to overcome the limitations of traditional noise reduction / insulation materials. Acoustic metasurfaces are characterized by their ultrathinness, openness, and ease of control; their excellent sound wave manipulation capabilities provide theoretical solutions and technical pathways for designing ultrathin, open low-frequency noise reduction / insulation structures.

[0003] Traditional resonant units follow the law of mass density. Traditional resonant units must increase the sound insulation by increasing the side length or surface density of the unit. The side length is generally 1 / 4 to 1 / 2 of the working wavelength. Therefore, they face the problem of large side length and high density in the low frequency range. Alternatively, after ensuring the side length and density, the sound energy density is low in the low frequency range, the sound energy loss efficiency is not high, and the sound attenuation effect is poor. Therefore, traditional resonant units cannot simultaneously guarantee the sound attenuation effect in the low frequency range and the side length of the resonant unit. Summary of the Invention

[0004] To simultaneously ensure the sound attenuation effect of both the side length and low-frequency range of the resonant unit, this invention provides a frequency-tuned, ultra-thin, multifunctional low-frequency sound attenuation device resonant unit and its application. The channel inlet and outlet of the coiled channel are connected by multiple transverse serpentine bends and multiple longitudinal serpentine bends, with right-angle bends between the transverse and longitudinal serpentine bends. This ensures that the side length of the resonant unit meets the depth subwavelength characteristics, thus simultaneously guaranteeing the sound attenuation effect of both the side length and low-frequency range of the resonant unit. In the low-frequency range, the ultra-thin resonant unit exhibits excellent sound absorption performance.

[0005] The technical solution adopted in this invention is:

[0006] A resonant unit for a frequency-modulated, ultra-thin, multifunctional low-frequency noise reduction device is disclosed. The resonant unit is an independent square resonant cavity structure, inside which is a square air resonant cavity. The air resonant cavity is surrounded by two end faces and four identical coiled channels located between the two end faces. The four coiled channels are centrally symmetrically distributed. The beginning and end of each coiled channel have a channel inlet communicating with the outside world and a channel outlet communicating with the air resonant cavity, respectively, allowing the air resonant cavity to communicate with the outside world through the coiled channels.

[0007] The entrance and exit of the convoluted channel are connected by multiple transverse or longitudinal serpentine bends; or:

[0008] The channel entrance and channel exit of the coiled channel are connected by multiple horizontal serpentine bends and multiple vertical serpentine bends, with right-angle bends between the horizontal and vertical serpentine bends.

[0009] Furthermore, the coiled channel has four transverse serpentine bends and two longitudinal serpentine bends; or two transverse serpentine bends and four longitudinal serpentine bends.

[0010] Furthermore, the wall thickness t of the coiled channel is 1mm≤t≤3mm, the width d of the coiled channel is 2mm≤d≤6mm, and the side length w of the resonant unit is w=12*t+11*d.

[0011] Furthermore, the resonant unit material is made of plexiglass or resin.

[0012] The purpose of the resonant unit is to arrange several resonant units with the same parameters in an array in front of the inner wall of a building space or equipment, with the entrance of any channel of the resonant unit facing the inner wall of the building space / equipment, for the absorption of low-frequency sound waves in the building space or equipment.

[0013] Furthermore, the spacing c between adjacent resonant units is 2w≤c≤8w, and the spacing q between the resonant unit and the inner wall of the building space / equipment is q≤20mm; the operating frequency range of the resonant unit applied to the inner wall of the building space / equipment is 310Hz-780Hz.

[0014] The purpose of the resonant unit is to provide grooves larger than the resonant unit arranged in an array on one or both inner walls of a square pipe / corridor / channel. The resonant unit is located in the groove and is surrounded on three sides. The entrance of any channel of the resonant unit faces the square pipe / corridor / channel and is used to absorb low-frequency sound waves in the square pipe / corridor / channel.

[0015] Furthermore, the width e of the gap between the resonant unit and the three sides of the groove is e≤20mm, and the spacing L between adjacent resonant units is w+2e≤L≤7w; the operating frequency range of the resonant unit applied to square pipes / corridors / channels is 240Hz-790Hz.

[0016] The resonant units described herein are arranged in an array of multiple rows to absorb low-frequency sound waves in an unenclosed environment.

[0017] Furthermore, several resonant units with identical parameters are arranged in an array in a double-row structure, with the spacing a between adjacent resonant units in the same row being 1.2w≤a≤1.6w; and the spacing b between two adjacent rows being 2.4w≤b≤3w.

[0018] The beneficial effects of this invention are:

[0019] The resonant unit of this invention has a side length of 1 / 11λ, exhibiting deep subwavelength characteristics and a peak sound energy absorption rate exceeding 0.95. This simultaneously ensures both the side length of the resonant unit and its noise reduction effect in the low-frequency range, achieving excellent sound absorption performance within this range. Furthermore, the resonant unit's space utilization can reach 15%, effectively improving space efficiency. Additionally, the operating frequency of the resonant unit can be adjusted by modifying the wall thickness t and width d of the coiled channel, facilitating its application in various working environments.

[0020] When the resonant unit described in this invention is applied to a square pipe / corridor / channel, the peak sound insulation rate of the resonant unit can still reach about 0.9 when the width of the square pipe / corridor / channel increases to 600mm, which shows excellent sound insulation performance of the square pipe / corridor / channel; and the variation of the spacing L between two adjacent resonant units within the range of less than 500mm has almost no impact on the working effect of the sound insulation device, which shows that the selection of the spacing between two adjacent resonant units is flexible.

[0021] When the resonant units described in this invention are used to form sound barriers, the sound insulation rate is less than -10dB in the frequency ranges of 550Hz-1450Hz and 1700Hz-2150Hz, with relative bandwidths of 90% and 23.4%, respectively, demonstrating excellent ultra-wideband low-frequency sound insulation performance. When sound barriers are used to form soundproof rooms, the sound insulation rate of the soundproof rooms is less than 0.1 in both the 600Hz-1500Hz and 1700Hz-2000Hz frequency bands, with corresponding relative bandwidths of 86% and 16%, respectively, demonstrating excellent ultra-wideband all-around low-frequency sound insulation effect. Furthermore, there are certain gaps between adjacent resonant units, which can achieve good ventilation. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the resonant unit in Embodiment 1 of the present invention.

[0023] Figure 2 This is a 3D printed sample of the resonant unit with one end face removed, as described in Embodiment 1 of the present invention.

[0024] Figure 3 This is a schematic diagram of the resonance unit described in Embodiment 2 of the present invention applied to the inner wall of a building space / equipment. The schematic diagram of the resonance unit in the figure is a cross-sectional view.

[0025] Figure 4 This is a spectrum of the acoustic energy absorption rate of the resonant unit in Embodiment 2 of the present invention.

[0026] Figure 5 This is a graph showing the relationship between the wall thickness t of the coiled channel and the operating frequency in Embodiment 2 of the present invention.

[0027] Figure 6 This is a graph showing the relationship between the width d of the coiled channel and the operating frequency in Embodiment 2 of the present invention.

[0028] Figure 7 This is a schematic diagram of the resonant unit described in Embodiment 3 of the present invention applied to a square pipe / corridor / channel. The schematic diagram of the resonant unit in the figure is a cross-sectional view.

[0029] Figure 8 This is a spectrum diagram of the sound insulation rate of the resonant unit in Embodiment 3 of the present invention.

[0030] Figure 9 This is a graph showing the relationship between the pipe width H and the peak sound insulation rate in Embodiment 3 of the present invention.

[0031] Figure 10 This is a graph showing the relationship between the spacing L between adjacent resonant units and the peak sound insulation rate in Embodiment 3 of the present invention.

[0032] Figure 11 This is a schematic diagram of the sound barrier composed of resonant units according to Embodiment 4 of the present invention. The schematic diagram of the resonant units in the figure is a cross-sectional view.

[0033] Figure 12 This is the experimental measurement device for the acoustic absorption performance of the resonant unit as described in Embodiment 4 of the present invention.

[0034] Figure 13 This is a spectrum of acoustic transmittance of the resonant unit simulated and measured according to Embodiment 4 of the present invention.

[0035] Figure 14 This is a schematic diagram of a soundproof room composed of resonant units as described in Embodiment 5 of the present invention. The schematic diagram of the resonant units in the figure is a cross-sectional view.

[0036] Figure 15 This is a sound insulation curve diagram of a simulated soundproof room in Embodiment 5 of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Resonant unit, 2. Rigid wall, 3. Groove, 4. Pipe wall, 5. Power amplifier, 6. Data controller, 7. Computer, 8. Miniature microphone, 9. Sound source, 10. Sound-absorbing sponge, 11. Waveguide, 12. Rigid load-bearing column, 101. Channel outlet, 102. Channel inlet, 103. Curved channel, 104. End face. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0040] Example 1

[0041] like Figure 1 and Figure 2 As shown, the resonant unit of the silencing device is an independent square resonant cavity structure, inside which is a square air resonant cavity. The air resonant cavity is surrounded by two end faces 104 and four identical coiled channels 103 located between the two end faces 104. The four coiled channels 103 are centrally symmetrically distributed. The beginning and end of each coiled channel 103 have a channel inlet 102 communicating with the outside and a channel outlet 101 extending towards the center of the air resonant cavity, so that the air resonant cavity is connected to the outside through the coiled channels 103. The channel inlet 102 and the channel outlet 101 of the coiled channel 103 are connected by four transverse serpentine bends and two longitudinal serpentine bends, and there is a right angle bend between the transverse serpentine bends and the longitudinal serpentine bends; or: the channel inlet 102 and the channel outlet 101 of the coiled channel 103 are connected by two transverse serpentine bends and four longitudinal serpentine bends, and there is a right angle bend between the transverse serpentine bends and the longitudinal serpentine bends. The wall thickness t of the coiled channel 103 is 1mm ≤ t ≤ 3mm, the width d of the coiled channel 103 is 2mm ≤ d ≤ 6mm, and the side length w of the resonant unit is w = 12*t + 11*d. The resonant unit of the silencing device can be fabricated using 3D printing technology, and the material used can be either plexiglass or resin.

[0042] Example 2

[0043] like Figure 3As shown, several resonant units with identical parameters are arranged in an array in front of the inner wall of a building space or equipment. The sound channel inlet 102 of each resonant unit faces the inner wall of the building space / equipment, forming a sound-absorbing wall structure. The sound energy absorption effect of the sound-absorbing wall is based on the excitation of the intrinsic resonance mode of the resonant unit. The sound energy is drawn into the unit and dissipated through the viscous friction between the air and the wall in the narrow channel, thereby achieving sound energy absorption. It can be used for sound absorption and sound insulation in building spaces and equipment shells to reduce noise pollution. The array arrangement rule is: the distance c between adjacent resonant units is 2w≤c≤8w, and the distance q between the resonant unit and the inner wall of the building space / equipment is q≤20mm.

[0044] The resonant units are arranged in an array in front of the wall according to the rule that the spacing between adjacent resonant units is c = 600 mm and the distance between the resonant unit and the wall is q = 10 mm. Each channel inlet 102 of the resonant unit faces the wall directly, meaning that two sides of the resonant unit are parallel to the wall, forming a sound-absorbing wall structure. The sound wave signal is incident perpendicularly to the wall surface. The parameters of the resonant unit used are: wall thickness of the coiled channel 103 t = 2 mm, width of the coiled channel 103 d = 6 mm, and side length of the resonant unit w = 90 mm. Figure 4 The spectrum of acoustic energy absorption rate in the simulation experiment conducted according to the above parameters and array arrangement is shown below. Figure 4 It can be seen that in this simulation experiment, the silencing device exhibits a sound energy absorption rate greater than 0.5 and a relative bandwidth of 8.2% in the frequency range of 336Hz-365Hz, demonstrating good low-frequency sound absorption performance. It reaches its peak at 352Hz, at which wavelength λ is...

[0045]

[0046] Where v is the speed of sound and f is the frequency. The ambient sound speed is 343 m / s, the calculated wavelength λ = 0.9744 m, and the side length of the resonant unit w = 90 mm, which is 1 / 11 of the working wavelength, exhibiting deep subwavelength characteristics. This ensures the sound attenuation effect of the resonant unit in the low-frequency range. Furthermore, the space ratio of the resonant unit is 15%, calculated as the side length w of the resonant unit / the distance c between adjacent resonant units, demonstrating that the sound-absorbing wall structure has ultra-sparse characteristics.

[0047] Similarly, the resonant units are arranged in an array in front of the wall according to the rule that the spacing between adjacent resonant units is c = 600 mm and the distance between the resonant unit and the wall is q = 10 mm, so that the entrance 102 of any channel of the resonant unit faces the wall directly, and the sound wave signal is incident perpendicular to the wall surface. The width d of the coiled channel 103 is fixed at d = 6 mm, and the wall thickness t of the coiled channel 103 is changed, respectively set to t = 1 mm, 2 mm, and 3 mm. Figure 5This demonstrates the relationship between the wall thickness t of the coiled channel 103 and the operating frequency. Figure 5 It can be seen that the operating frequency of the sound-absorbing wall structure can be changed by adjusting the wall thickness t of the coiled channel 103. The larger the wall thickness t of the coiled channel 103, the lower the operating frequency of the sound-absorbing wall structure, and the peak frequency of the sound absorption spectrum curve varies in the range of 430Hz-700Hz, which reflects the adjustability of the operating frequency of the sound-absorbing wall structure.

[0048] Similarly, the resonant units are arranged in an array in front of the wall according to the rule that the spacing between adjacent resonant units is c = 600 mm and the distance between the resonant unit and the wall is q = 10 mm, so that the entrance 102 of any channel of the resonant unit faces the wall directly, and the sound wave signal is incident perpendicularly to the wall surface. The wall thickness t of the coiled channel 103 is fixed at t = 2 mm, and the width d of the coiled channel 103 is changed to d = 3 mm, 4 mm, and 5 mm respectively. Figure 6 This demonstrates the relationship between the width d of the coiled channel 103 and the operating frequency. Figure 6 It can be seen that the operating frequency of the sound-absorbing wall structure can be changed by adjusting the width d of the coiled channel 103. The larger the width d of the coiled channel 103, the lower the operating frequency of the sound-absorbing wall structure, and the peak frequency of the sound absorption spectrum curve varies in the range of 394Hz-560Hz, which reflects the adjustability of the operating frequency of the sound-absorbing wall structure.

[0049] In addition, the operating frequency of the sound-absorbing wall structure will scale proportionally with the overall structural parameters of the resonant unit. When all the structural parameters of the resonant unit are doubled, its operating frequency will decrease to half of the original. Conversely, if all the structural parameters of the resonant unit are reduced to half of the original, its operating frequency will increase to twice the original. The operating frequency is adjustable between 310Hz and 780Hz.

[0050] Example 3

[0051] like Figure 7 As shown, grooves 3 larger than the resonant units are arranged in an array on one or both inner walls of the square pipe / corridor / channel. The resonant units are located within the grooves 3 and are surrounded on three sides. The sound channel inlet 102 of the resonant units faces the square pipe / corridor / channel, forming a sound insulation device for absorbing low-frequency sound waves in the square pipe / corridor / channel. The sound insulation effect of the sound insulation device for the square pipe / corridor / channel is based on the sound absorption and sound reflection caused by the excitation of the intrinsic resonance mode of the resonant unit. The width e of the gap between the resonant unit and the groove 3 on the three sides is e≤20mm, and the spacing L between adjacent resonant units is w+2e≤L≤7w.

[0052] Two grooves 3, larger than the resonant units, are arranged in an array on one side of the inner wall of the square pipe. The two resonant units are located in the grooves 3 and surrounded on three sides. The channel entrance 102 of each resonant unit faces the square pipe / corridor / channel, forming a sound insulation device. The sound wave signal is emitted parallel to the pipe. The width of the gap between the resonant unit and the groove 3 on three sides is e = 10mm. The spacing between adjacent resonant units is L = 300mm. A pipe with a width of H = 400mm is used. The parameters of the resonant unit used are: wall thickness of the coiled channel 103 t = 2mm, width of the coiled channel 103 d = 6mm, and side length of the resonant unit is w = 90mm. Figure 8 The spectrum of acoustic energy absorption rate in the simulation experiment conducted according to the above parameters and arrangement is shown below. Figure 8 It can be seen that the sound insulation rate of the structure reaches 0.98 at 262Hz, exhibiting excellent sound insulation effect, and the sound insulation rate exceeds 0.8 in the frequency band of 250-276Hz, with a relative bandwidth of 10%. At the same time, the resonant unit does not affect the effective ventilation area of ​​the duct.

[0053] Similarly, two grooves 3, larger than the resonant units, are arranged in an array on one side of the inner wall of the square pipe. The two resonant units are located within the grooves 3 and surrounded on three sides. The channel inlet 102 of each resonant unit faces the square pipe / corridor / channel, forming a sound insulation device. Sound waves are emitted parallel to the pipe. The three-sided gap between the resonant unit and the groove 3 is e = 10mm, and the spacing between adjacent resonant units is L = 300mm. The parameters of the resonant unit used are: wall thickness of the coiled channel 103 t = 2mm, width of the coiled channel 103 d = 6mm, and side length of the resonant unit w = 90mm. Adjusting the width H of the pipe yields... Figure 9 The curve showing the relationship between pipe width H and peak sound insulation rate is from... Figure 9 It can be seen that when the pipe width H increases to 500mm, the peak sound insulation rate remains above 0.95, and when the pipe width increases to 600mm, it can still reach about 0.9, which demonstrates the excellent sound insulation performance of the pipe.

[0054] Similarly, two grooves 3, larger than the resonant units, are arranged in an array on one side of the inner wall of the square pipe. The two resonant units are located within the grooves 3 and surrounded on three sides. The sound channel inlet 102 of each resonant unit faces the square pipe / corridor / channel, forming a sound insulation device. Sound waves are emitted parallel to the pipe. The three-sided gap between the resonant unit and the groove 3 is e = 10mm. A pipe with a width H = 400mm is used. The parameters of the resonant unit are: wall thickness t = 2mm for the coiled channel 103, width d = 6mm for the coiled channel 103, and side length w = 90mm for the resonant unit. The spacing L between adjacent resonant units is adjusted to obtain... Figure 10 The curve showing the relationship between the spacing L between adjacent resonant units and the peak sound insulation rate is shown from... Figure 10It can be seen that the variation of the spacing L between two adjacent resonant units within the range of less than 500mm has almost no impact on the working effect of the sound insulation device, demonstrating the flexibility in selecting the spacing between two adjacent resonant units.

[0055] Example 4

[0056] like Figure 11 As shown, several resonant units with the same parameters are arranged in an array to form a multi-row structure, forming a sound barrier for the absorption of low-frequency sound waves in non-enclosed environments. Its noise reduction effect is based on the combined effect of the excitation of multiple intrinsic resonant modes of the resonant unit 1 and the bandgap effect of the periodic structure. The spacing a between adjacent resonant units in the same row is 1.2w≤a≤1.6w; the spacing b between two adjacent rows is 2.4w≤b≤3w.

[0057] Simulations were performed using Comsol software to construct a resonant element with a wall thickness of t = 2 mm, a width of d = 3 mm, and a side length of w = 57 mm for the coiled channel 103. The material used had a density of 1180 kg / m³. 3 Epoxy resin with a longitudinal wave velocity of 2720 m / s and a transverse wave velocity of 1460 m / s was used, with simulated environmental parameters including an air density of 1.21 kg / m³. 3 The sound velocity is 343 m / s. Several resonant units are arranged in two rows, with a spacing of a = 80 mm between adjacent resonant units in the same row and a spacing of b = 160 mm between the two rows. Sound waves are incident perpendicularly onto the sound barrier. The relationship between the sound insulation rate and frequency of the simulated sound barrier is obtained. Figure 13 Spectrum diagram of simulated sound insulation rate.

[0058] like Figure 12 As shown, the simulation experiment was verified using a four-sensor measurement method. The experimental setup included a power amplifier 5, a data controller 6, a computer 7, a miniature microphone 8, sound-absorbing sponge 10, and a waveguide 11. The resonant unit of the sample under test was placed in the middle of the waveguide 11. Four acquisition points were set on the wall of the waveguide 11, with each pair of acquisition points evenly distributed on both sides of the sample under test. The miniature microphone 8 was set on each acquisition point and connected to the data controller 6 for the acquisition and recording of sound wave information. The data controller 6 was connected to the computer 7 to realize the transmission of data and signals. The data controller 6 was connected to the sound source 9 through the power amplifier 5 to realize the control of the sound source 9. The sound source 9 was set at one end of the waveguide 11 to emit sound waves. Sound-absorbing sponges 10 were set at both ends of the waveguide 11 to absorb the residual sound waves after the sample under test was soundproofed.

[0059] The dimensions and material parameters of the tested samples are the same as in the simulation experiment. Two tested samples are arranged parallel to each other along the direction of waveguide 11, with a distance b = 160 mm between them, achieving a two-row arrangement. Waveguide 11 is constructed of acrylic sheet, and its width is 80 mm, equal to a in the simulation experiment. Sound waves are emitted parallel to waveguide 11, and miniature microphones 8 at both ends of the tested samples collect sound wave information before and after sound insulation. This information is then transmitted by data controller 6 to computer 7 for recording and processing, resulting in... Figure 13 The acoustic transmittance spectrum was measured. Figure 13 As can be seen, the simulation and measurement results are in good agreement, and the sound transmittance of the sound barrier is less than -10dB in the frequency ranges of 550Hz-1450Hz and 1700Hz-2150Hz, with relative bandwidths of 90% and 23.4% respectively, demonstrating excellent ultra-wideband low-frequency sound insulation performance. In addition, there are certain gaps between adjacent resonant units, which can achieve good ventilation.

[0060] Example 5

[0061] The sound barrier in Example 4 is assembled into a multi-faceted soundproof room. Specifically, the soundproof room is supported by four rigid load-bearing columns 12. The four rigid load-bearing columns 12 are connected to form four faces. Two rows of several resonant units with the same parameters are arranged in an array on the four faces to form a two-layer grid-like structure, which constitutes a four-sided soundproof wall.

[0062] The resonant unit adopts a coiled channel 103 with a wall thickness of t=2mm, a width of d=3mm, and a side length of w=57mm. The arrangement rules of the resonant unit array are as follows: the distance between adjacent resonant units in the same row is a=70mm, the distance between two rows is b=150mm, and the sound source point is set at the center point O of the soundproof room. Figure 15 To simulate the sound insulation curve of a soundproof room, from Figure 15 As can be seen from the data, the sound insulation rate of the soundproof room is less than 0.1 in both the 600Hz-1500Hz and 1700Hz-2000Hz frequency bands, with corresponding relative bandwidths of 86% and 16% respectively, demonstrating excellent ultra-wideband all-round low-frequency sound insulation effect. In addition, there are certain gaps between adjacent resonant units, resulting in good ventilation performance.

[0063] The examples described are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the protection scope of the present invention.

Claims

1. A resonant unit of a frequency-tunable, ultra-thin, multi-functional low-frequency sound-attenuation device, characterized by: The resonance unit is a separate square resonant cavity structure, and a square air resonant cavity is arranged in the resonance unit; the air resonant cavity is surrounded by two end faces (104) and four structure-same meandering channels (103) arranged between the two end faces (104); the four meandering channels (103) are arranged in a central symmetry; the meandering channel (103) has a sound channel inlet (102) and a sound channel outlet (101) which are respectively connected with the outside and the air resonant cavity, so that the air resonant cavity is connected with the outside through the meandering channel (103); The sound channel inlet (102) and the sound channel outlet (101) of the meandering channel (103) are connected by a plurality of transverse serpentine bends or longitudinal serpentine bends; or The sound channel inlet (102) and the sound channel outlet (101) of the meandering channel (103) are connected by a plurality of transverse serpentine bends and a plurality of longitudinal serpentine bends, and the transverse serpentine bends and the longitudinal serpentine bends have right-angle bends therebetween.

2. The resonant unit of claim 1, wherein: When the sound channel inlet (102) and the sound channel outlet (101) of the meandering channel (103) are connected by a plurality of transverse serpentine bends and a plurality of longitudinal serpentine bends, the meandering channel (103) has four transverse serpentine bends and two longitudinal serpentine bends; or the meandering channel (103) has two transverse serpentine bends and four longitudinal serpentine bends.

3. The resonant unit of claim 2, wherein: The wall thickness t of the meandering channel (103) is 1mm≤t≤3mm, the width d of the meandering channel (103) is 2mm≤d≤6mm, and the side length w of the resonance unit is w=12*t+11*d.

4. The resonant unit of claim 1, wherein: The resonance unit is made of organic glass or resin.

5. Use of the resonance unit according to any one of claims 1-4 for low frequency sound absorption in a building space or installation, characterized in that: A plurality of resonance units with the same parameters are arranged in an array in front of the inner wall of a building space or equipment, and any sound channel inlet (102) of the resonance unit faces the inner wall of the building space / equipment, so as to absorb low-frequency sound waves in the building space or equipment.

6. The method of use of the resonant unit according to claim 5 for low frequency sound absorption in architectural spaces or devices, characterized in that: The distance c between adjacent resonance units is 2w≤c≤8w, w is the side length of the resonance unit, the distance q between the resonance unit and the inner wall of the building space / equipment is q≤20mm; the working frequency range of the resonance unit applied to the inner wall of the building space / equipment is 310Hz-780Hz.

7. The method of using the resonant unit of any one of claims 1-4 for low frequency sound absorption in a square duct / hallway / corridor, characterized in that: The inner wall of one side or both sides of the square pipeline / corridor / channel is arranged with a groove (3) larger than the resonance unit in an array, the resonance unit is located in the groove (3) and is surrounded by three sides, and any sound channel inlet (102) of the resonance unit faces the square pipeline / corridor / channel, so as to absorb low-frequency sound waves in the square pipeline / corridor / channel.

8. The method of using the resonant unit of claim 7 for low frequency sound absorption in a square duct / corridor / tunnel, characterized by: The gap width e between the resonance unit and the groove (3) is e≤20mm, the distance L between adjacent resonance units is w+2e≤L≤7w, w is the side length of the resonance unit; the working frequency range of the resonance unit applied to the square pipeline / corridor / channel is 240Hz-790Hz.

9. Use of the resonator unit according to any one of claims 1 to 4 for the absorption of low frequency sound waves in an unconfined environment, characterized in that: A plurality of resonance units with the same parameters are arranged in an array in a multi-row structure, and are used for absorbing low-frequency sound waves in a non-closed environment.

10. The method of claim 9, wherein the method is used in a non-enclosed environment. The resonance units with the same parameters are arranged in an array into a double-row structure, the distance a between adjacent resonance units in the same row is 1.2w≤a≤1.6w, w is the side length of the resonance unit; the distance b between the adjacent two rows is 2.4w≤b≤3w.

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