Low-broadband sound absorber and sound absorption method of seat for railway vehicle

Abstract

The low-broadband sound absorption body is composed of at least one low-broadband sound absorption unit, each low-broadband sound absorption unit is composed of a closed cavity with a sound wave incidence hole and a sound absorption body arranged in the closed cavity, the sound absorption body is provided with a wave absorption modulation channel, and the sound wave incidence hole of the closed cavity is opposite to the wave absorption modulation channel of the corresponding sound absorption body. And sound waves are guided into the wave absorption modulation channel through the sound wave incidence hole. Impedance cooperative coupling is formed under the cross-scale multi-parameter cooperative design of the incidence hole, the porous sound absorption material and the wave absorption modulation channel, wave absorption energy consumption is achieved, effective absorption of low-frequency noise is formed, the multiple low-broadband sound absorption units synchronously absorb sound waves to form multi-cavity tuning resonance, the sound absorption frequency band is widened, low-frequency broadband efficient sound absorption is achieved, and the sound absorption efficiency is improved. The number of low-broadband sound absorption units in the low-broadband sound absorber and the sound absorption frequency band corresponding to each low-broadband sound absorption unit are designed, and targeted absorption of low-frequency broadband noise is achieved. The invention further provides a sound absorption method of the seat for the railway vehicle.

Description

Technical Field

[0001] The invention relates to a low-bandwidth sound absorber and a sound absorption method for a rail vehicle seat, belonging to the technical field of sound absorption structures. Background Art

[0002] With the rapid development of rail transit and the continued increase in train speeds, in-car noise levels are also increasing, directly impacting passenger and driver comfort. When a train operates at high speeds, external wheel-rail noise, traction equipment noise, and aerodynamic noise are transmitted through the train body into the interior, generating both direct and reverberant sound. Noise transmitted through the underfloor is the primary component. Currently, measures to control in-car noise in rail vehicles primarily employ composite sound insulation structures, filling with sound-absorbing materials, and spraying / applying damping coatings in body components such as the floor, ceiling, and side walls to block noise transmission into the vehicle. However, these noise reduction measures only reduce structural vibration and direct sound; they cannot mitigate the reverberant sound already forming within the vehicle. Furthermore, these noise reduction measures are effective at reducing mid- and high-frequency noise, but less effective at reducing low-frequency noise. Consequently, after body insulation, in-car noise is dominated by low-frequency components. Seats are important sound absorbers in rail vehicles, numerous and covering a large total sound absorption area. Improving their sound absorption performance, particularly their low-frequency sound absorption, can effectively reduce in-vehicle reverberation and overall noise levels, thereby lowering noise levels within the train. Conventional rail vehicle seats typically utilize polyurethane or silicone foam pads in the seat cushions or backrests for sound absorption. Their sound absorption performance depends primarily on the material's microscopic parameters (porosity, flow resistance, tortuosity, viscous characteristic length, thermal characteristic length, etc.) and overall thickness. For example, patent document CN201520718175.6 discloses a seat for high-speed rail vehicles, CN201520718198.7 discloses a sound-absorbing seat for rail vehicles, and CN201520718807.9 discloses a sound-absorbing seat for high-speed trains. The sound absorption structure of current rail vehicle seats has good sound absorption effect in the medium and high frequencies, but the sound absorption effect is poor at low frequencies, which makes it difficult to meet the noise reduction target requirements. In addition, the sound absorption design cannot be carried out according to the frequency characteristics of the noise inside the vehicle, making it difficult to achieve good low-frequency broadband sound absorption performance. Summary of the Invention

[0003] The low-bandwidth sound absorber provided by the present invention achieves impedance synergistic coupling through the cross-scale, multi-parameter collaborative design of the incident hole, porous sound-absorbing material, and wave-canceling modulation channel, achieving wave absorption energy consumption and effectively absorbing low-frequency noise. Multiple low-bandwidth sound-absorbing units simultaneously absorb sound waves to form multi-cavity tuned resonance, broadening the sound absorption band. This provides excellent sound absorption performance in the low-bandwidth range of 100 to 800 Hz, achieving low-frequency, broadband, and efficient sound absorption. The number of low-bandwidth sound-absorbing units in the low-bandwidth sound absorber and the corresponding sound absorption frequency band of each low-bandwidth sound absorber are designed to ensure that the sound absorption band of the low-bandwidth sound absorber covers the low-frequency range of noise, achieving targeted absorption of low-frequency, broadband noise. The present invention also provides a sound absorption method for rail vehicle seats.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: A low-bandwidth sound absorber is composed of at least one low-bandwidth sound absorbing unit, characterized in that the low-bandwidth sound absorbing unit is composed of a sealed chamber with a sound wave inlet hole and a sound absorber arranged in the sealed chamber and made of a porous sound absorbing material, the sound absorber is provided with a wave-canceling modulation channel, the sound wave inlet hole of the sealed chamber is arranged opposite to the wave-canceling modulation channel of the corresponding sound absorber, and the sound wave is introduced into the wave-canceling modulation channel through the sound wave inlet hole.

[0005] Preferably, it is composed of multiple low-wideband sound absorbing units connected in parallel, and the closed cavities of the multiple low-wideband sound absorbing units are arranged and combined together to form a combined cavity. The combined cavity is composed of a cavity box, a partition that divides the inner cavity of the cavity box into multiple independent sub-cavities, and a surface cover covering the cavity box. The surface cover seals the sub-cavities to form a closed cavity, and the surface cover is provided with openings corresponding to the sub-cavities to form sound wave incident holes for the closed cavity.

[0006] Preferably, at least two of the sealed chambers have different shapes, cross-sectional areas and depths, and the shape, cross-sectional area and thickness of the sound absorber are adapted to the corresponding sealed chambers.

[0007] Preferably, the sound absorber is cut and formed from fiber or foam sound absorbing cotton, and the number, cross-sectional shape, depth and arrangement of the wave-absorbing modulation channels on the sound absorber in each low-bandwidth sound absorbing unit are not exactly the same.

[0008] Preferably, the aperture of the sound wave entrance hole is 1~5mm, the perforation rate of the perforation area of ​​the sound wave entrance hole on each closed chamber is 1%~40%, and the cross-sectional area of ​​the wave-absorbing modulation channel on the sound absorber is larger than the cross-sectional area of ​​the sound wave entrance hole on the corresponding closed chamber.

[0009] Preferably, a side opening is provided on the side of the cavity box, and a wave-cutting modulation channel opposite to the side opening is provided on the side of the sound absorber.

[0010] Preferably, the number of the low-bandwidth sound absorbing units is single, and multiple sound absorbers are placed in the closed chamber. The closed chamber consists of a single cavity and a surface cover. The surface cover seals the single cavity to form a closed chamber. An opening corresponding to the single cavity is opened on the surface cover to form a sound wave incident hole for the closed chamber. The sound absorbers are arranged according to the inner shape of the single cavity.

[0011] A method for absorbing sound of a rail vehicle seat, using the low broadband sound absorber described above to achieve sound absorption of the seat, is characterized by comprising the following steps: S1. Based on the low-frequency range of the noise in the carriage under the operating conditions of the rail vehicle, the number of low-band sound absorbing units in the low-band sound absorber and the sound absorption frequency band corresponding to each low-band sound absorbing unit are designed so that the sound absorption frequency band of the low-band sound absorber covers the low-frequency range of the noise in the carriage; S2, determining the shape and size of the low broadband sound absorber based on the spatial shape and size of the corresponding installation position on the seat frame; S3, manufacturing a corresponding low broadband sound absorber based on the data obtained in steps S1 and S2 and in combination with the lightweight requirements of the rail vehicle; S4, installing the low broadband sound absorber at the corresponding mounting position of the bottom seat frame, with the sound wave incident hole of the sealed cavity facing downward; S5. When the rail vehicle is running, the sound waves in the carriage are shot into the sealed cavity through the sound wave incident hole and enter the wave elimination modulation channel. The sound waves form a soft boundary sound cavity resonance in the wave elimination modulation channel to achieve wave elimination modulation. Under the coordination of the incident hole, porous sound-absorbing material and wave elimination modulation channel, impedance cooperative coupling is formed to achieve wave absorption energy consumption, forming the incidence, modulation, wave elimination and energy consumption of the sound waves, and realizing the sound absorption of the seats.

[0012] Preferably, "designing the sound absorption frequency band corresponding to each low-bandwidth sound absorption unit" specifically refers to designing the shape, cross-sectional area, depth of the closed cavity, the porous sound absorption material, cross-sectional shape, area, thickness of the sound absorber, and the number, cross-sectional shape, depth and arrangement of the wave-absorbing modulation channels.

[0013] The beneficial effects of the invention are: The low-bandwidth sound absorber of the present invention is composed of at least one low-bandwidth sound absorbing unit. A single low-bandwidth sound absorbing unit is composed of a closed chamber and a sound absorber. A sound wave inlet hole is provided on the closed chamber, and a wave elimination modulation channel is provided on the sound absorber. The sound wave inlet hole and the wave elimination modulation channel are arranged relative to each other. Sound waves are injected into the closed chamber from the sound wave inlet hole and enter the wave elimination modulation channel, thereby realizing concentrated and efficient injection of sound waves. The sound waves form soft-boundary acoustic cavity resonance in the wave elimination modulation channel, realizing wave elimination modulation, and then enter the porous sound absorbing material. Under the cross-scale multi-parameter collaborative design of the inlet hole, the porous sound absorbing material and the wave elimination modulation channel, impedance collaborative coupling is formed to realize wave absorption energy consumption and form effective absorption of low-frequency noise. Multiple low-bandwidth sound absorbing units synchronously absorb sound waves to form multi-cavity tuned resonance, thereby broadening the sound absorption frequency band and playing a role in the low-bandwidth range of 100-800 Hz. Excellent sound absorption performance, achieving low-frequency and broadband high-efficiency sound absorption, combined with the porous sound-absorbing material with good medium and high-frequency sound absorption characteristics, forming a synchronous absorption of low-bandwidth and medium and high-frequency sound waves, thereby improving the sound absorption effect; according to the low-frequency range of the noise, the number of low-bandwidth sound absorbing units in the low-bandwidth sound absorber and the sound absorption frequency band corresponding to each low-bandwidth sound absorbing unit can be designed, so that the sound absorption frequency band of the low-bandwidth sound absorber covers the low-frequency range of the noise, thereby achieving targeted absorption of low-frequency broadband noise, and applying the low-bandwidth sound absorber to the seats of rail vehicles can be designed according to the low-frequency range of the noise in the car under the operating conditions of the rail vehicle, so that the sound absorption frequency band of the low-bandwidth sound absorber covers the low-frequency range of the noise in the car, thereby improving the noise reduction effect on the low-frequency noise in the car during the operation of the rail vehicle, effectively reducing the reverberation sound and the total noise level in the car, and improving riding comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the low broadband sound absorber in Example 1.

[0015] Figure 2 Schematic diagram of the combined cavity.

[0016] Figure 3 Schematic diagram of a sound absorber.

[0017] Figure 4 Schematic diagram of the exploded view of the low broadband sound absorber in Example 1.

[0018] Figure 5 Schematic diagram of a cavity box with side openings and a sound absorber with wave-absorbing and modulation channels on the side.

[0019] Figure 6 Schematic diagram of the low broadband sound absorber in the second embodiment. DETAILED DESCRIPTION

[0020] The following combination Figures 1 to 6 The embodiments of the present invention are described in detail. Example 1

[0021] A low-bandwidth sound absorber is composed of at least one low-bandwidth sound absorbing unit 1, characterized in that the low-bandwidth sound absorbing unit comprises a sealed chamber 2 with a sound wave inlet hole A and a sound absorber 3 disposed in the sealed chamber 2 and made of a porous sound absorbing material. The sound absorber 3 is provided with a wave-canceling modulation channel 4. The sound wave inlet hole A of the sealed chamber 2 is arranged opposite to the wave-canceling modulation channel 4 of the corresponding sound absorber 2, and the sound wave is introduced into the wave-canceling modulation channel 4 through the sound wave inlet hole A.

[0022] The low-bandwidth sound absorber described above is composed of at least one low-bandwidth sound absorbing unit 1. A single low-bandwidth sound absorbing unit is composed of a closed chamber 2 and a sound absorber 3. A sound wave inlet A is opened on the closed chamber 2, and a wave elimination modulation channel 4 is opened on the sound absorber 3. The sound wave inlet A and the wave elimination modulation channel 4 are arranged opposite to each other. The sound wave is injected into the closed chamber from the sound wave inlet A and enters the wave elimination modulation channel 4, so as to realize the concentrated and efficient injection of the sound wave. The sound wave forms a soft boundary acoustic cavity resonance in the wave elimination modulation channel 4 to realize wave elimination modulation, and then enters the porous sound absorbing material. Under the cross-scale multi-parameter collaborative design of the inlet A, the porous sound absorbing material and the wave elimination modulation channel 4, impedance collaborative coupling is formed to realize wave absorption energy consumption and form effective absorption of low-frequency noise. Multiple low-bandwidth sound absorbing units synchronously absorb sound waves to form multi-cavity tuned resonance, thereby broadening the sound absorption frequency band and achieving low-bandwidth sound absorption of 100~800Hz. The frequency range can play an excellent sound absorption performance, realize low-frequency broadband high-efficiency sound absorption, and combined with the porous sound-absorbing material with good medium and high frequency sound absorption characteristics, form a synchronous absorption of low-band and medium and high frequency sound waves, thereby improving the sound absorption effect; according to the low-frequency range of the noise, the number of low-band sound absorbing units 1 in the low-band sound absorber and the sound absorption frequency band corresponding to each low-band sound absorbing unit 1 can be designed, so that the sound absorption frequency band of the low-band sound absorber covers the low-frequency range of the noise, thereby realizing targeted absorption of low-frequency broadband noise, and the low-band sound absorber can be used in the seats of rail vehicles. The low-band sound absorber can be designed according to the low-frequency range of the noise in the car under the operating conditions of the rail vehicle, so that the sound absorption frequency band of the low-band sound absorber covers the low-frequency range of the noise in the car, thereby improving the noise reduction effect of the low-frequency noise in the car during the operation of the rail vehicle, effectively reducing the reverberation sound and the total noise level in the car, and improving the riding comfort.

[0023] The structure is composed of multiple low-bandwidth sound absorbing units 1 connected in parallel. The closed chambers 2 of the multiple low-bandwidth sound absorbing units 1 are arranged and combined together to form a combined cavity. The combined cavity is composed of a cavity box 5, a partition 6 that divides the inner cavity of the cavity box 5 into multiple independent sub-cavities, and a surface cover 7 covering the cavity box 5. The surface cover 7 seals the sub-cavities to form a closed cavity. The surface cover 7 is provided with openings corresponding to the sub-cavities to form the sound wave incident holes A of the closed cavity. Figure 2As shown, a plurality of sub-cavities are separated by partitions 6 in the cavity box 5, and the sound absorber 3 is placed in the sub-cavity. The surface cover 7 is covered on the cavity box 5 to seal the cavity box 5 to form a plurality of sealed closed chambers 2. The surface cover 7 is opened according to the distribution of the closed chambers 2 to form sound wave entrance holes A for the sealed closed chambers 2. The surface cover 7 is fixed to the cavity box 5 by bolts to form a firm overall structure. The attenuation modulation channel 4 of the sound absorber 3 corresponds to the sound wave entrance hole A. When installed, the surface cover 7 is facing the direction of sound wave injection so that the sound wave is injected from the sound wave entrance hole A and enters the attenuation adjustment channel 4.

[0024] At least two of the sealed chambers 2 have different shapes, cross-sectional areas, and depths, and the shape, cross-sectional area, and thickness of the sound absorber 3 are adapted to the corresponding sealed chamber 2. Because the sound absorption frequencies corresponding to each low-bandwidth sound absorbing unit 1 are not exactly the same, the sealed chambers 2 have at least two sizes and depths. Therefore, the sound absorption frequency band of the corresponding low-bandwidth sound absorbing unit 1 can be adjusted by designing the shape, cross-sectional area, and depth of the sealed chamber 2, thereby meeting the requirement for independently designing the sound absorption frequency band of each low-bandwidth sound absorbing unit 1.

[0025] The sound absorber 3 is cut and formed from fiber or foamed sound-absorbing cotton. The number, cross-sectional shape, depth, and arrangement of the wave-canceling modulation channels 4 on the sound absorber 3 vary within each low-bandwidth sound absorbing unit 1. The wave-canceling modulation channels 4 on the sound absorber 3 are used to form soft-boundary acoustic cavity resonance, achieve wave-canceling modulation, and achieve impedance cooperative coupling with the porous sound-absorbing material. Different numbers, cross-sectional shapes, depths, and arrangements of the wave-canceling modulation channels 4 on the sound absorber 3 result in different sound absorption frequencies for the corresponding low-bandwidth sound absorbing units 1. Therefore, the sound absorption frequency band of the corresponding low-bandwidth sound absorbing units 1 can be adjusted by designing the number, cross-sectional shape, depth, and arrangement of the wave-canceling modulation channels 4 on the sound absorber 3.

[0026] The aperture of the acoustic wave incident hole A is 1 to 5 mm, the perforation rate of the perforated area of ​​the acoustic wave incident hole A in each sealed chamber 2 is 1% to 40%, and the cross-sectional area of ​​the wave-canceling modulation channel 4 on the sound absorber 3 is larger than the cross-sectional area of ​​the acoustic wave incident hole A in the corresponding sealed chamber 2. The sealed chamber 2 uses a large aperture and a high perforation rate to form an array of acoustic wave incident holes A, ensuring that both low-frequency sound waves and medium- and high-frequency sound waves can enter the interior of the sound absorber 3, ensuring the reliability of sound absorption. As a soft-boundary acoustic cavity, the cross-sectional area of ​​the wave-canceling modulation channel 4 must be larger than the cross-sectional area of ​​the corresponding acoustic wave incident hole A to ensure the reliability of the modulation and wave-canceling.

[0027] The cavity box 5 has a side opening 51 formed on its side, and the sound absorber 3 has a side opening 51 formed on its side, opposite to the side opening 51, and a wave-canceling modulation channel 4 formed on its side. To increase the penetration rate of sound waves and further enhance the sound absorption effect, the side opening 51 is formed on the cavity box 5, and the wave-canceling modulation channel 4 is formed on the sound absorber 3, opposite to the side opening 51, so that sound waves can also enter the sealed chamber 2 from the side and enter the wave-canceling modulation channel 4. Example 2

[0028] The difference from the first embodiment is that: the number of the low-bandwidth sound absorbing unit 1 is single, and multiple sound absorbers 3 are placed in the closed chamber 2. The closed chamber 3 consists of a single cavity 8 and a surface cover 7. The surface cover 7 seals the single cavity 8 to form the closed chamber 2. The surface cover 7 is provided with an opening corresponding to the single cavity 8 to form the sound wave incident hole A of the closed chamber 2. The sound absorbers 3 are arranged according to the inner shape of the single cavity 8. Figure 6 It can be seen that the inner cavity of the single cavity 8 is not separated by a partition and is an integral cavity. Multiple sound absorbers 3 are arranged in the single cavity 8 according to the inner cavity shape of the single cavity 8. The surface cover 7 covers the single cavity 8. The sound wave incident hole A on the surface cover 7 corresponds to the wave elimination modulation channel 4 on the sound absorber 3. The sound wave is injected into the closed cavity from the sound wave incident hole A and enters the wave elimination modulation channel 4, realizing concentrated and efficient injection of the sound wave. The sound wave forms a soft boundary acoustic cavity resonance in the wave elimination modulation channel 4 to realize wave elimination modulation, and then enters the porous sound absorbing material. Under the cross-scale multi-parameter collaborative design of the incident hole, the porous sound absorbing material and the wave elimination modulation channel, impedance collaborative coupling is formed to realize wave absorption energy consumption and form effective absorption of low-frequency noise. The molding of the closed cavity 2 is simpler and easier to assemble.

[0029] The present invention also protects a method for absorbing sound of a rail vehicle seat, which uses the low broadband sound absorber described above to achieve sound absorption of the seat, and is characterized by comprising the following steps: S1, based on the low-frequency range of the noise in the carriage under the operating conditions of the rail vehicle, design the number of low-band sound absorbing units 1 in the low-band sound absorber and the sound absorption frequency band corresponding to each low-band sound absorbing unit 1, so that the sound absorption frequency band of the low-band sound absorber covers the low-frequency range of the noise in the carriage; S2, determining the shape and size of the low broadband sound absorber based on the spatial shape and size of the corresponding installation position on the seat frame; S3, manufacturing a corresponding low broadband sound absorber based on the data obtained in steps S1 and S2 and in combination with the lightweight requirements of the rail vehicle; S4, install the low broadband sound absorber on the corresponding mounting position of the bottom seat frame, and set the sound wave incident hole A of the sealed cavity 2 downward; S5, when the rail vehicle is running, the sound waves in the carriage are shot into the sealed cavity through the sound wave incident hole A and enter the wave elimination modulation channel 4. The sound waves form a soft boundary sound cavity resonance in the wave elimination modulation channel 4 to achieve wave elimination modulation. Under the coordination of the incident hole, porous sound absorbing material and wave elimination modulation channel, impedance cooperative coupling is formed to achieve wave absorption energy consumption, forming the incidence, modulation, wave elimination and energy consumption of the sound waves, and realizing sound absorption of the seats.

[0030] The sound absorption method described above applies low-bandwidth sound absorbers to rail vehicle seats. The low-bandwidth sound absorbers are designed based on the low-frequency range of the noise in the car under the operating conditions of the rail vehicle, so that the sound absorption frequency band of the low-bandwidth sound absorber covers the low-frequency range of the noise in the car, thereby improving the noise reduction effect of the low-frequency noise in the car during the operation of the rail vehicle, effectively reducing the reverberation sound and the total noise level in the car, and improving riding comfort.

[0031] Specifically, "designing the sound absorption frequency band corresponding to each low-bandwidth sound absorption unit" refers to designing the shape, cross-sectional area, and depth of the enclosed chamber 2; the porous sound-absorbing material, cross-sectional shape, area, and thickness of the sound absorber 3; and the number, cross-sectional shape, depth, and arrangement of the wave-canceling modulation channels. The enclosed chamber 2 and sound absorber 3 within the low-bandwidth sound absorption unit 1 are designed to adjust the sound absorption frequency band corresponding to the low-bandwidth sound absorption unit 1. The sound absorption band of the low-bandwidth sound absorber formed by connecting multiple low-bandwidth sound absorption units 1 in parallel covers the low-frequency range of the noise inside the vehicle cabin, achieving targeted absorption of low-frequency, broadband noise within the vehicle cabin.

[0032] The above fully describes the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings. It should be noted that the embodiments described are only part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Claims

1. A low-bandwidth sound absorber, comprising at least one low-bandwidth sound absorbing unit, characterized in that: The low-bandwidth sound absorbing unit is composed of a sealed chamber with a sound wave inlet hole and a sound absorbing body made of a porous sound absorbing material and arranged in the sealed chamber. The sound absorbing body is provided with a wave-canceling modulation channel. The sound wave inlet hole of the sealed chamber is arranged opposite to the wave-canceling modulation channel of the corresponding sound absorbing body, and the sound wave is introduced into the wave-canceling modulation channel through the sound wave inlet hole.

2. The low broadband sound absorber according to claim 1, characterized in that: It is composed of multiple low-bandwidth sound absorbing units connected in parallel. The closed cavities of the multiple low-bandwidth sound absorbing units are arranged and combined together to form a combined cavity. The combined cavity is composed of a cavity box, a partition that divides the inner cavity of the cavity box into multiple independent sub-cavities, and a surface cover covering the cavity box. The surface cover seals the sub-cavities to form a closed cavity, and the surface cover is provided with openings corresponding to the sub-cavities to form sound wave incident holes for the closed cavity.

3. The low broadband sound absorber according to claim 2, characterized in that: At least two of the sealed chambers have different shapes, cross-sectional areas and depths, and the shape, cross-sectional area and thickness of the sound absorber are adapted to the corresponding sealed chambers.

4. The low broadband sound absorber according to claim 2, characterized in that: The sound absorber is cut and formed from fiber or foam sound absorbing cotton. The number, cross-sectional shape, depth and arrangement of the wave-absorbing modulation channels on the sound absorber in each low-bandwidth sound absorbing unit are not exactly the same.

5. The low broadband sound absorber according to claim 1, characterized in that: The aperture of the sound wave entrance hole is 1~5mm, the perforation rate of the perforation area of ​​the sound wave entrance hole on each closed chamber is 1%~40%, and the cross-sectional area of ​​the wave-breaking modulation channel on the sound absorber is larger than the cross-sectional area of ​​the sound wave entrance hole on the corresponding closed chamber.

6. The low broadband sound absorber according to claim 2, characterized in that: A side opening is provided on the side of the cavity box, and a wave-cutting modulation channel opposite to the side opening is provided on the side of the sound-absorbing body.

7. The low broadband sound absorber according to claim 1, characterized in that: The number of the low-bandwidth sound absorbing units is single, and multiple sound absorbers are placed in the closed chamber. The closed chamber consists of a single cavity and a surface cover. The surface cover seals the single cavity to form a closed chamber. An opening corresponding to the single cavity is opened on the surface cover to form a sound wave incident hole for the closed chamber. The sound absorbers are arranged according to the inner shape of the single cavity.

8. A method for absorbing sound of a seat for a railway vehicle, wherein the low-bandwidth sound absorber according to any one of claims 1 to 7 is used to absorb sound of the seat, characterized in that: The following steps are involved: S1. Based on the low-frequency range of the noise in the carriage under the operating conditions of the rail vehicle, the number of low-band sound absorbing units in the low-band sound absorber and the sound absorption frequency band corresponding to each low-band sound absorbing unit are designed so that the sound absorption frequency band of the low-band sound absorber covers the low-frequency range of the noise in the carriage; S2, determining the shape and size of the low broadband sound absorber based on the spatial shape and size of the corresponding installation position on the seat frame; S3, manufacturing a corresponding low broadband sound absorber based on the data obtained in steps S1 and S2 and in combination with the lightweight requirements of the rail vehicle; S4, installing the low broadband sound absorber at the corresponding mounting position of the bottom seat frame, with the sound wave incident hole of the sealed cavity facing downward; S5. When the rail vehicle is running, the sound waves in the carriage are shot into the sealed cavity through the sound wave incident hole and enter the wave elimination modulation channel. The sound waves form a soft boundary sound cavity resonance in the wave elimination modulation channel to achieve wave elimination modulation. Under the coordination of the incident hole, porous sound-absorbing material and wave elimination modulation channel, impedance cooperative coupling is formed to achieve wave absorption energy consumption, forming the incidence, modulation, wave elimination and energy consumption of the sound waves, and realizing the sound absorption of the seats.

9. The method for absorbing sound of a rail vehicle seat according to claim 8, characterized in that: "Designing the sound absorption frequency band corresponding to each low-bandwidth sound absorption unit" specifically refers to designing the shape, cross-sectional area, and depth of the enclosed cavity, the porous sound absorption material, cross-sectional shape, area, and thickness of the sound absorber, and the number, cross-sectional shape, depth, and arrangement of the wave-canceling modulation channels.

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