465 results about "Frequency sound" patented technology

The invention discloses a high-reliability data transmission method and device based on multi-frequency sound waves. The device comprises a transmitting end which is connected with a sound-producing device for transmitting a sound wave signal, and a receiving end which is connected with a receiving device for receiving the sound wave signal, wherein the transmitting end comprises a data coding unit and a multi-frequency sound wave transmitting unit; and the receiving end comprises a data decoding unit and a multi-frequency sound wave receiving unit. The high-reliability data transmission method and the device based on multi-frequency sound waves provided by the invention have low hardware requirements, data transmission can be performed by only arranging a loudspeaker and a microphone, the method and the device can be applied to mobile phones and computers, and quick realization of application and services at low cost is facilitated; and during data decoding, a probability sequence is referred, and a calibration method is adopted, so that the hit rate and accuracy of data are increased effectively.

The invention relates to low-frequency sound absorption needling non-woven composite materials and a preparation method of the low-frequency sound absorption needling non-woven composite materials and application of the low-frequency sound absorption needling non-woven composite materials. The composite materials comprise kapok fibers or hollow Dacron non-woven fabric and polyethylene films. The preparation method comprises: mixing, opening, carding and meshing are conducted to 60%-90% kapok fibers and 40%-10% hollow Dacron non-woven fabric according to mass percent; a fiber mesh is inputted in a needling machine so as to conduct needling reinforcement, the fiber mesh is reeled and cut off so as to obtain kapok or hollow Dacron needle non-woven fabric; the polyethylene films in 0.06mm-0.10mm are smoothly placed on one side of the needle non-woven fiber mesh, and are composited, taken out and cooled, and then the low-frequency sound absorption needling non-woven composite materials are obtained. The composite materials can be applied to the field of automotive trim, construction, high-speed rail and the like. The sound absorption materials have the advantages of being light in weight, simple in operation of the preparation method, good in economic benefit and suitable for industrial production.

The invention discloses a double-vibrating-diaphragm speaker module which comprises a single speaker body and a peripheral shell for accommodating the single speaker body. The single speaker body comprises a first vibrating diaphragm, a voice coil, a magnetic circuit and a second vibrating diaphragm, a first sound outlet and a second sound outlet communicating with the outside are formed in the peripheral shell, a first sound cavity communicating with the first sound outlet is formed between the first vibrating diaphragm and the peripheral shell, a second front sound cavity communicating with the second sound outlet is formed between the second vibrating diaphragm and the peripheral shell, a space between the first vibrating diaphragm and the second diaphragm is communicated with a rear sound cavity. The double-vibrating-diaphragm speaker module of the structure can be used with a double-vibrating-diaphragm speaker, so that low-frequency sound effect of the speaker module is improved, and acoustic performance of the double-vibrating-diaphragm speaker module is improved.

The invention discloses a three-dimensional multiple moving objects locating method and a corresponding apparatus which make use of multi-frequency sound waves. The method figures out the distances between an objective point and each receiving point according to the dynamic Doppler frequency deviation and phase differences of a measurement signal sent by the objective point and a measurement signal received by the receiving point and then gets a three-dimensional coordinate of the objective point in a referential coordinate system through a three-dimensional space geometric computation. The apparatus comprises a control unit and an objective sensor unit which are mutually connected with or without wire; wherein, the control unit comprises a digital signal processor, a modem, an oscillator, a multi-channel AD converter and a plurality of frequency dividers; the objective sensor unit comprises a plurality of objective apparatuses and a plurality of receiving sensors; the objective apparatus consists of a sensor provided with an on-off function and a transmission energy convertor; the oscillator is connected with a plurality frequency dividers. The invention has high locating accuracy for three-dimensional moving objects and high anti-interruption capability, and the structure of the apparatus is simple and the arrangement and use are convenient. The invention is applicable to various locating sites.

The invention relates to full-frequency sound absorbing cotton which is provided with a double-layer structure or three-layer structure. The full-frequency sound absorbing cotton of the double-layer structure is composed of a melt-blow high polymer fiber layer and a varicosity polytetrafluoroethylene layer. The full-frequency sound absorbing cotton of the three-layer structure is composed of a melt-blow high polymer fiber layer with double faces compounded with the varicosity polytetrafluoroethylene layer or the varicosity polytetrafluoroethylene layer with double faces compounded with the melt-blow high polymer fiber layer. A high-performance composite micropore thin layer new material has better full-frequency sound absorbing capacity; is environment-friendly, non-toxic and free of peculiar smell, volatile gas, pollution or carcinogenic substances; and is free of stimulation caused by operating similar glass fiber on the skin, can be machined in punching mode, and does not generate dust or scraps and the like. The sound absorbing cotton made of the two materials of the melt-blow high polymer fiber layer and the varicosity polytetrafluoroethylene layer has good thermal resistance, and a sound absorbing effect cannot be affected by high-humidity climate and water.

The invention provides a laser mosquito killing device. The device comprises a mosquito recognition unit, an infrared detection unit, a laser device, a calibration unit, a control unit and an image scanning unit. According to the specific flapping frequency sound wave characteristic of mosquitos, the device can detect the existence of mosquitos and fix the positions of mosquitos, the laser device can be started to burn the body and wings of mosquitos so that the mosquitos fall down and lose the capability of approaching to the living body. The calibration unit of the device can also calibrate the emission range of the laser device, so as to guarantee the safety of articles placed in the working area of the device and the safety of human or animals in the working area of the device. In addition, the infrared detection unit of the device can stop emission of laser beams when detecting the overlapping of position of the living body and the emission direction of the laser beam.

The invention discloses a detection method and a device of a loudspeaker. The detection method comprises the following steps: collecting sound signals played by the loudspeaker to be tested; Performing discrete short-time Fourier transform on the sound signal to obtain a time-frequency sound signal corresponding to each sampling frequency; Wherein the time-frequency sound signal comprises a signalstrength corresponding to a sampling frequency at each sampling time; Dividing all sampling frequencies according to preset frequency intervals to obtain a plurality of frequency intervals; Calculating a signal strength sum of the sampling frequency in the frequency interval at the corresponding sampling time according to the time-frequency sound signal corresponding to the sampling frequency ineach frequency interval; According to the signal strength, judging whether there is abnormal sound fault in the loudspeaker to be tested. According to the detection method of the present invention, itis possible to quickly and effectively detect whether the loudspeaker has abnormal sound fault or not.

The invention provides a high-frequency acoustic wave resonator and a preparation method thereof. The high-frequency acoustic wave resonator comprises a high-acoustic-velocity support substrate, an insulating dielectric layer which is located on the upper surface of the high-sound-velocity supporting substrate, a piezoelectric film which is located on the upper surface of the insulating dielectriclayer, and an interdigital electrode which is located on the upper surface of the piezoelectric film. By arranging the high-sound-velocity supporting substrate below the piezoelectric film, the soundvelocity of target elastic waves excited and propagated in the piezoelectric film can be increased, propagation of the target elastic waves can be effectively restrained, and the resonant frequency of the high-frequency sound wave resonator is improved; the insulating dielectric layer is arranged between the piezoelectric film and the high-sound-velocity supporting substrate, the leakage of electric field energy in the piezoelectric film can be effectively reduced, and the electromechanical coupling coefficient of the high-frequency sound wave resonator can be enhanced; by selecting the appropriate insulating dielectric layer, temperature compensation can be carried out on the high-frequency acoustic wave resonator, temperature drift of the high-frequency acoustic wave resonator is reduced, and temperature stability of the high-frequency acoustic wave resonator is improved.

The invention discloses a method for positioning an underwater low-frequency sound source by laying acoustic sensor arrays in the air, which comprises the steps: (1) laying two round acoustic sensor arrays on any horizontal plane in the air, measuring an acoustic pressure signal, estimating directions of arrival of the sound source from the projection position on the horizontal plane to the sensor arrays, and determining the position of the projection of the sound source on the horizontal plane according to the two directions of arrival; (2) freely selecting two sensors in certain array, drawing a change curve of the sound pressure difference at the two positions along with the depth of the sound source based on a law of low-frequency acoustic transmission of underwater point sources, and determining possible depths of the underwater sound source through one-dimensional search according to the actually measured sound pressure difference; and (3) determining the depth of the underwater sound source by calculating and comparing average deviations of measured values and theoretical values of sound pressure differences among all sensors in the array under various possible depths. The method can cheaply, simply and conveniently position underwater target sound sources, and has great practical value.

A loudspeaker with low-frequency oscillation, comprising: a housing (21) with a ring portion (211) extending inwardly from the bottom thereof; and a reed element (22) having a top end attached to an oscillatable sound assembly, the reed element (22) further having an external ring (221) and two vibration arms (222) symmetrically extending from the internal side of the external ring (221) to the internal side of the loudspeaker in a bent manner, each of the vibration arms (222) having a free end (223) extending to the center of the reed element (22), the oscillatable sound assembly including either a magnetic ring (25) or a coil (28) disposed within the housing (21), the ring portion (211) being attached to either another coil corresponding to the magnetic ring (25) or another magnetic ring corresponding to the coil (28), whereby, when the coil (28) is fed with electric current, a magnetic force is created to impart an up and down vibration to the oscillatable sound assembly, thereby enhancing the effect of the low-frequency sound field as well as the resonance effect.

The invention, which relates to the field of metamaterial sound insulation, discloses a lightweight honeycomb type low-frequency sound insulation metamaterial structure which comprises an upper frame,a lower frame, elastic thin films arranged between the two frames, a mass blocks attached to the films and a homogeneous thin plate covering the outer sides of the frames. Each frame is composed of aplurality of regularly arranged hexagonal honeycomb units, and the honeycomb units of the upper frame and the lower frame are in one-to-one correspondence in position. The mass blocks are attached tothe elastic thin films of all honeycomb units, the mass blocks can be all identical or different in type and are arranged in a combined mode according to a certain rule, wherein the shapes of the mass blocks comprise a circular ring shape, a cylindrical shape and a circular truncated cone shape. The used honeycomb type acoustic metamaterial is superior to a traditional sound insulation material and has very excellent sound insulation performance in a low-frequency band; the overall quality of a structure can be controlled effectively by selecting a light frame material, so that the purposes of light weight and low-frequency sound insulation are achieved. The lightweight honeycomb type low-frequency sound insulation metamaterial structure has very broad application prospects in the fieldsof automobiles, buildings and the like.

The invention relates to a method for accurately drawing downhole conditions of an oil field by acoustic emission located monitoring, which comprises the steps of: arranging at least three signal receivers in any direction at intervals on the ground around a water injection well to collect dynamic signals of a formation fracture of the water injection well and process time difference; pressing liquid into the water injection well by a fracture and water injection device, wherein the liquid pressed into the underground rock stratum enables the rock stratum crack or close and the liquid flows to generate a low frequency sound, and receiving and processing the signal by a low frequency sound signal receiving and processing device; checking and measuring a sound source signal according to the signal and drawing a right angle coordinate map corresponding to the distribution of each sound source signal by using the water injection well as an origin so as to obtain the downhole conditions of the water injection well accurately. According to the invention, a changing low-frequency sound can be formed by pressing liquid into an oil storage layer of the water injection well effectively so that a downhole condition map of the water injection well can be quickly and accurately drawn, and the economic benefit of the oil field can be greatly improved.

The invention discloses a sound based gesture recognition method. A normal microphone and a loudspeaker are used as hardware supports for receiving and transmitting signals, the loudspeaker generates high-frequency sounds difficult for human ears to perceive, the microphone receives sound signals rebounded in limb movements, spectral analysis is conducted by the aid of physical phenomenon Doppler effect of the rebounded sound signals, acquired information of the limb movements is defined as corresponding logic signals, and operations of a computer are controlled by the aid of the logic signals. A brand-new man-computer interaction method is provided in the aspect of computer control, and interesting user experience and interaction feelings can be brought to computer users.

The invention relates to an infrasound sensor array telemetric system of a micro-electronic mechanical system in the telemetric field. A data detecting control system controls a scanning orientation control system; the scanning orientation control system controls an ultralow-frequency sound wave emitting system and a micro-electronic mechanical frequency coupling sensor array and transmits feedback information to a data analyzing system; an ultralow-frequency sound wave bunch emitting system emits detecting sound wave to a geologic structure, and the detecting sound wave passes through the micro-electronic mechanical frequency coupling sensor array; the micro-electronic mechanical frequency coupling sensor array receives low-frequency signals, carries out frequency mixing and coupling for the low-frequency signals, transforms the low-frequency signals into medium-frequency signals; measuring frequency coupling signals are transmitted to an analog-to-digital conversion data transmitting network to carry out analog digital signal conversion; measured data is transmitted to a data analyzing system and a data detecting and controlling system to carry out information exchange; and analyzed data result and the feedback information are transmitted to the data detecting and controlling system. The system has the advantages of fast testing speed, strong response ability and high quality of data transmission.

The invention discloses a muffling structure which comprises more than two layers of resonant film materials. The adopted film is soft, uneven in surface and has airflow barrier. The surface of the film is uneven on the basis of the soft film, so that the absorption peak of the resonant structure deflects to the low frequency, the absorption of the low frequency is promoted; and moreover, when the medium-high frequency sound is incident from different angles, the sound waves have a chance to reflect on the surface of the film repeatedly; and therefore, the opportunity that the sound waves pass through the airflow barrier film is greatly increased, the strong reflection of the smooth airflow barrier film on the medium-high frequency sound is avoided, most of the medium-high frequency sound can enter the structure to be absorbed, and the absorption of the medium, high and low-frequency sound is considered.

The invention discloses an ultrathin multi-absorption-peak low-frequency sound absorber, aims to solve the problem that each cavity of a low-frequency sound absorber can only cause one quasi-perfect absorption frequency peak, and belongs to the technical field of sound wave processing. The ultrathin multi-absorption-peak low-frequency sound absorber comprises a perforated cover plate, an embeddedround hole, a helical partition plate, a non-perforated baffle plate, a bottom plate and one or more perforated baffle plates, wherein a through hole is formed in the center of the perforated cover plate; the helical partition plate comprises a cylindrical shell and a helical structure; the helical structure is placed in the cylindrical shell; the tail part of the helical structure is connected with the inner wall of the cylindrical shell, thereby forming a helical channel; the helical partition plate is placed between the perforated cover plate and the bottom plate, and a sound absorption cavity is formed inside the helical partition plate; the non-perforated baffle plate is inserted between the outermost circle of the helical structure and a cylindrical wall; the non-perforated baffle plate is used for isolating channels of different widths; and a plurality of embedded round holes of different sizes are formed under the through hole of the perforated cover plate and above the throughhole of the perforated baffle plate to form sound absorbers of different wavelengths, thereby realizing the multi-absorption-peak low-frequency sound absorber.

The invention discloses a full-band super-structure sound absorber. The full-band super-structure sound absorber comprises a frame body and a sound absorber body which is fixedly arranged in the frame body and used for absorbing noise, wherein the sound absorber body is sequentially provided with a front panel, a high-frequency sound absorber body, an intermediate-frequency resonant cavity, an impedance matching layer and a low-frequency sound absorber body in the sound source propagation direction; and the thickness of the sound absorber body in the sound source propagation direction ranges from 150mm to 400mm. The high-frequency sound absorber body is formed by arranging a plurality of micro-perforated plates in series, and a back cavity used for absorbing sound is formed between every two adjacent micro-perforated plates; the front panel is a metal perforated plate and plays a role in protecting the high-frequency sound absorber body; the intermediate-frequency resonant cavity is a regular quadrangular prism; the impedance matching layer is of an aerogel or film resonant structure; and the low-frequency sound absorber body is of a flat plate sound absorption structure of a resonant cavity array. The full-band super-structure sound absorber does not contain porous sound absorption materials, is good in environment resistance, long in service life, compact in structure, small in thickness and good in full-band sound absorption performance, and can be used for a silent chamber, a semi-anechoic chamber and a full-anechoic chamber.

The invention discloses a down-like sound insulation material and a preparation method thereof. The down-like sound insulation material is prepared by compounding one or more of hollow polyester, hollow polypropylene, spandex, rubber fibers and PTT (polytrimethylene terephthalate) fibers and PP (polypropylene) / elastomer melt-blown superfine short fibers and then compounding upper and lower thin films. The down-like sound insulation material has a surface density of 50 to 500g / m<2>, a thickness of 5 to 50mm and a high-frequency sound absorption coefficient of more than 0.56. A lightweight, thinand efficient velvet-like sound insulation material is developed by improving existing melt-flowing equipment, and can be widely applied to lining materials of automobiles, acoustic screens, buildings and the like.

The invention discloses a landmine multi-modal vibration mode measurement device and method. The landmine multi-modal vibration mode measurement device comprises a signal generator, a sound emission unit, a sound level meter, a laser Doppler vibrometer, a multi-channel data acquisition card, a computer and a caisson, wherein the signal generator is connected with the sound emission unit through a data line; the sound level meter and the laser Doppler vibrometer are sequentially connected with the multi-channel data acquisition card and the computer through data lines; high-intensity and low-frequency sound waves with continuous sweep frequency are emitted out through the signal generator and the sound emission unit, the sound level meter and the laser Doppler vibrometer detect the sound pressure level of the upper end face of a landmine and an amplitude-frequency characteristic curve of the vibration speed respectively, and the multi-order inherent frequency of the landmine is measured out; the signal generator and the sound emission unit emit high-intensity sound wave signals with the inherent frequency of the landmine as the output frequency, and the laser Doppler vibrometer, the multi-channel data acquisition card and the computer detect, display and record a multi-modal vibration mode of the landmine. The landmine multi-modal vibration mode measurement device and method achieve non-contact type rapid and accurate measurement of the multi-modal vibration mode of the landmine.

The invention discloses a multi-layer film type acoustic meta-material structure and a design method thereof. The meta-material structure comprises a plurality of stacked film type acoustic meta-material units with different structural parameters, and each meta-material unit is divided by a hard frame to form the wide-frequency-band low-frequency sound insulation structure with a plurality of sound insulation peaks. The method comprises the following steps: calculating the sound insulation peak frequency of a meta-material unit; and according to the sound insulation peak frequency, constructing the acoustic meta-material structure in one form of equal spacing, peak value and valley value complementing and noise source customization. The structure can be applied to various vehicles and building decoration, and a brand new noise reduction method is provided for creating a low-noise environment.

In an audiovisual system, in which video is displayed on a screen that does not permit sound to pass through the screen, such as a light emitting diode panel, a high-frequency speaker positioned above an audience seating area can direct sound toward the screen, so that the screen can reflect the sound toward the audience seating area. The high-frequency speaker can be used with one or more low-frequency speakers positioned at or near the height of the audience seating area. The low-frequency and high-frequency sounds can appear to originate from close to the same height, thereby creating a realistic audio image at the audience seating area. A spectral filter can negate the spectral effects of propagation to and reflection from the screen. Suitable time delays can synchronize the high-frequency sound with the low-frequency sound and with video displayed on the screen.

The invention relates to a strip-shaped loudspeaker box with mirror image type low-frequency radiators. A box body is in a long flat strip shape. Low-frequency radiator installation holes symmetrical in position are formed in the upper and lower surfaces of the right half part, in the long axis direction, of the box body respectively, and the two low-frequency radiators are correspondingly installed in the two upper and lower low-frequency radiator installation holes in a mirror symmetry mode. A mid-low-pitch loudspeaker installation hole is formed in the left half part, in the long axis direction, of the box body, a mid-low-pitch loudspeaker is installed in the mid-low-pitch loudspeaker installation hole, and the mid-low-sound loudspeaker radiates sounds towards the part over the box body. A high-pitch loudspeaker installation table is arranged on the front side face of the left end, in the long axis direction, of the box body, a high-pitch loudspeaker is installed on the high-pitch loudspeaker installation table, and the high-pitch loudspeaker radiates sounds towards the part right ahead of the box body. The strip-shaped loudspeaker box has the acoustic properties of being small in distortion, good in low frequency, capable of bearing high power and excellent in high-frequency performance; the transient stability of the loudspeaker box can be improved, and thus the loudspeaker box can achieve a good sound effect when radiating low-frequency sounds.

The invention relates to a device for regulating and controlling low-frequency sound insulation performance of a sandwich plate structure and a parameter determination method thereof, and belongs to the technical field of sound absorption and sound insulation. The device comprises an upper panel, an upper frame, a flexible plate, a lower frame and a lower panel which are sequentially combined from top to bottom, a through hole is formed in the upper panel, and a mass block is arranged on the flexible plate; and the upper frame and the lower frame are the same in structure and are both composed of criss-cross partition plates, the whole device is divided into a plurality of periodic units, and each periodic unit is correspondingly provided with a through hole and a mass block. The low-frequency sound insulation performance of an existing sandwich plate structure can be improved under the condition that the mass (surface density) and the thickness of the sandwich plate are kept unchanged. Meanwhile, a special sound transmission theoretical model can be established for the device to be used for directly calculating the sound insulation index of the device and accurately regulating and controlling the frequency of a sound insulation peak of the device, and has good engineering application prospects.

In an audiovisual system, in which video is displayed on a screen that does not permit sound to pass through the screen, such as a light emitting diode panel, a high-frequency speaker positioned above an audience seating area can direct sound toward the screen, so that the screen can reflect the sound toward the audience seating area. The high-frequency speaker can be used with one or more low-frequency speakers positioned at or near the height of the audience seating area. The low-frequency and high-frequency sounds can appear to originate from close to the same height, thereby creating a realistic audio image at the audience seating area. A spectral filter can negate the spectral effects of propagation to and reflection from the screen. Suitable time delays can synchronize the high-frequency sound with the low-frequency sound and with video displayed on the screen.

The invention relates to the technical field of headset, and discloses a passive radiation type micro speaker comprising a speaker frame and a loudspeaking component coaxially arranged in the speaker frame. A first through hole penetrating inside and outside of the speaker frame is formed in the center of the bottom of the speaker frame, a second through hole is formed in a position, opposite to the first through hole, on the loudspeaking component, and the first through hole is provided with a passive radiation frame opposite to the second through hole; a damping fin is arranged on the upper ring of the outer end face of the bottom side of the speaker frame. The invention further discloses a headset comprising the passive radiation type micro speaker. The passive radiation type micro speaker has the advantages that since the first through hole penetrating the inside and outside of the speaker frame is formed in the center of the bottom of the speaker frame, the second through hole is formed in the position, opposite to the first through hole, on the loudspeaking component, the first through hole is provided with the passive radiation frame opposite to the second through hole, and the damping fin is arranged on the outer end face of the bottom side of the speaker frame, the passive radiation frame and the damping fin are utilized to produce proper acoustic impedance, low-frequency sound quality is improved, and distortion is reduced.

The invention discloses a remote high-directivity low-frequency sound wave transmission and measurement device and a method. The device comprises a computer, a signal processor, an acoustics parametric array, a sound level meter and a data acquisition card; the computer is sequentially connected with the data acquisition card, the signal processor and the acoustics parametric array through wires to form a sound wave transmission system; the sound level meter is sequentially connected with the data acquisition card and the computer through wires to form a sound wave measurement system; a high-directivity high-frequency sound wave is transmitted by the sound wave transmission system, a low-frequency sound wave is generated on a to-be-detected reference position, and a sound wave frequency and a sound pressure level amplitude on the to-be-detected reference position are detected by a sound pressure level detector. The remote high-directivity low-frequency sound wave transmission and measurement device and the method can achieve remote and high-directivity transmission and real-time measurement of a low-frequency sound wave.

The invention discloses a ground surface sound impedence rate measuring device and a ground surface sound impedence rate measuring method. The device comprises a sound wave emission system, a device for detecting a sound pressure level of the ground surface to be tested, and a device for detecting a vibration speed of the ground surface to be tested, wherein the sound wave emission system comprises a signal generator, a sound console, a power amplifier, a loudspeaker, a sound level meter and a computer; the device for detecting the sound pressure level of the ground surface to be tested comprises a sound wave emission system, a sound level meter and a computer; and the device for detecting the vibration speed of the ground surface to be tested comprises a sound wave emission system, a seismic detector array, a multi-channel data acquisition unit and a computer. The sound wave emission system emits high-intensity low-frequency sound waves, the device for detecting the sound pressure level detects a sound pressure level of the ground surface to be tested, the device for detecting the vibration speed of the ground surface detects a vibration speed on the ground surface, and a ratio of the sound pressure level and the vibration speed on the ground surface is a ground surface sound impedence rate. By the ground surface sound impedence rate measuring device and the ground surface sound impedence rate measuring method, the ground surface sound impedence rate can be quickly measured at high accuracy.

The invention discloses a bone conduction loudspeaker, a bone conduction earphone and a bone conduction hearing aid. The bone conduction loudspeaker comprises a magnetic assembly; a voice coil; an elastic assembly which comprises a first elastic piece and a second elastic piece, wherein the first elastic piece and the second elastic piece are installed at the two opposite ends of the magnetic assembly respectively, and the voice coil is electrically connected to the first elastic piece or the second elastic piece; a conduction piece connected to the second elastic piece; a supporting part connected with the first elastic part and the second elastic part, wherein a magnetic gap is formed between the magnetic assembly and the supporting part, and the voice coil is installed in the magnetic gap. During working, the elastic assembly and the magnetic assembly vibrate together; the bone conduction earphone or the bone conduction hearing aid comprises the bone conduction loudspeaker. The boneconduction loudspeaker provided by the invention can be made to be small in size and is beneficial to low-frequency sound wave transmission.

The invention discloses a light medium- and low-frequency sound absorption material and a preparation method thereof. The material comprises meltblown non-woven fabric which is used as a substrate, and further comprises a polyacrylonitrile nanofiber membrane or a polyacrylonitrile / titanium dioxide nanofiber membrane which covers the substrate. According to the preparation method, the static spinning technology is adopted and the polyacrylonitrile nanofiber membrane or the polyacrylonitrile / titanium dioxide nanofiber membrane is prepared on the meltblown non-woven fabric substrate. The materialhas relatively good medium- and low-frequency sound absorption performance, the preparation operation method is simple, one-step lamination is realized and post-treatment processing or other lamination processes are omitted.

Provided is a sound-absorbing material that is thin and lightweight and is excellent in low-frequency sound-absorbing property. The sound-absorbing material of the present invention includes a laminated structure including in this order: a first perforated layer; a first porous layer; a second perforated layer; and a second porous layer, wherein the first perforated layer has a plurality of through-holes in its thickness direction, wherein the second perforated layer has a plurality of through-holes in its thickness direction, and wherein the first perforated layer has a thickness of less than 1 mm.