Abstract: A noise reduction assembly includes an outer frame and a partition plate. An accommodating cavity is arranged in the outer frame; the partition plate is arranged in the accommodating cavity, and the partition plate and the outer frame form a noise reduction channel, the noise reduction channel includes a first noise reduction section, a second noise reduction section and a third noise reduction section that are communicated in sequence, and the channel cross-sectional areas of the first noise reduction section and the third noise reduction section are both smaller than the channel cross-sectional area of the second noise reduction section. The technical solution of the present application may reduce the noise of a new energy equipment having the noise reduction assembly during operation.

Abstract: A hearing device containing a housing enclosing a housing interior, and a loudspeaker for generating acoustic signals. In addition, the hearing device contains a damping element formed by a damping mat, which is interposed between the loudspeaker and a wall of the housing or a loudspeaker box. The damping mat contains at least one damping chamber filled with fluid.

Abstract: Disclosed herein is an acoustic metamaterial structure which can effectively reduce noise in a specific frequency range through formation of an acoustic bandgap, wherein the specific frequency range is determined by a periodic structure formed by an array of multiple unit cells. The acoustic metamaterial structure includes multiple first unit cells each including a first space having a first cross-sectional area and a second space disposed downstream of the first space in a flow direction of fluid to communicate with the first space, the second space having a second cross-sectional area larger than the first cross-sectional area, wherein the acoustic metamaterial structure reduces noise in a specific frequency range through formation of an acoustic bandgap, the specific frequency range being determined by a periodic structure formed by an array of the first space and the second space.

Abstract: Provided is a sheet-shape electrostatic sound pressure-electrical signal conversion device that is three-dimensionally deformable and has a low drive voltage. The sound pressure-electrical signal conversion device includes a polymer sheet sandwiched between a pair of electrodes facing each other, the polymer sheet is a dielectric film, at least one of the electrodes includes an insulating flexible substrate having a plurality of through-holes and a plurality of conductive fibers having one end fixed to the flexible substrate with a pressure sensitive adhesive, electrical conduction in an in-plane direction is formed by contact between the conductive fibers, the conductive fibers are vibrated by giving an electrical signal to the pair of electrodes or the conductive fibers are vibrated by receiving sound pressure to cause the pair of electrodes to output an electrical signal.

Abstract: A generator of acoustic waves for submarine environments has a hollow body that extends along an axis delimited by a first closed end and by a second end that is provided with an acoustic diffuser member. The hollow body has a first cylindrical portion delimited by the first end that houses a first piston and a second cylindrical portion delimited by the second end that houses a second piston in a freely axially sliding manner. The second piston is mechanically free from the first piston and has a face that faces the acoustic diffuser member. An impulsive actuator is configured together with the first piston to move the first piston towards the second piston. An adjustor for a longitudinal motion of the second piston is arranged between the first piston and the second piston.

Abstract: A process for manufacturing a device and the device for damping pressure pulsations for a compressor of a gaseous fluid, in particular a refrigerant, in a refrigerant circuit of a motor vehicle air-conditioning system. The device exhibits a housing that encompasses a chamber and features at least two outlet openings. Here, the housing is constructed between tubular connecting lines, whose ends are aligned with one another. An insert element for reducing the cross-sectional area of the pass-through opening is arranged inside at least one of the pass-through openings.

Abstract: Provided are acoustic articles, and related methods, that include a porous layer and heterogeneous filler received in the porous layer. The heterogeneous filler can include clay, diatomaceous earth, graphite, glass bubbles, polymeric filler, non-layered silicate, plant-based filler, or a combination thereof, and can have a median particle size of from 1 micrometer to 1000 micrometers and a specific surface area of from 0.1 m2/g to 800 m2/g. The acoustic article can have an overall flow resistance of from 100 MKS Rayls to 8000 MKS Rayls. The acoustic articles can serve as acoustic absorbers, vibration dampers, and/or acoustic and thermal insulators.

Abstract: A voice communication relay device for use in combination with a protective face mask having an embedded microphone, a headset, a radio, and a push-to-talk (PTT) device that is connected to a radio. The voice communication relay device includes: a housing; a device speaker associated with the housing; an amplifier in the housing, the amplifier being electrically connected to the device speaker; a circuit board located inside of the housing; and a power source. At least one function of the circuit board is to serve as an Impedance dependent auto switch (IDAS) that is electrically connected to the device speaker and an output connector for selectively sending signals to the device speaker or to a radio that is connected to the PTT device.

Abstract: A resonator insert (14) is provided for coaxial and sectionally radially spaced insertion in an intake pipe of a turbocharger (10). The resonator insert (14) has a tube section (141) with a wall having circumferentially extending, axially adjacent through-slots (142). The wall of the tube section (141) carries at least one radially outwardly directed, axially extending lamella (144) crossing the through-slots (142). A turbocharger with an upstream resonator also is provided.

Abstract: A suppressor for a firearm may comprise a baffle stack. The baffle stack may comprise a plurality of baffles coupled along an axis. The plurality of baffles may form an outer fluid path and an inner fluid path that are radially fluidly separate. The outer fluid path may comprise an outer fluid path inlet, which is also an outer fluid path outlet for the outer fluid path, such that gas that enters the outer fluid path through the outer fluid path inlet also exits the outer fluid path through the outer fluid path inlet, and exits the suppressor through the inner fluid path.

Abstract: A speaker includes a housing having a receiving space, a speaker unit and a cavity received in the receiving space, sound-absorbing particles filled in the filling cavity, a filling hole opened in the housing and communicating with the filling cavity for filling the sound-absorbing particles into the filling cavity, a hole cover covering the filling hole and a resilient member filled in the filling hole. The resilient member can deform in the height direction of the filling hole, and the resilient member is sandwiched in a compressed state between the hole cover and the sound-absorbing particles. Compared with the related art, the sound-absorbing particles of the speaker disclosed by the present disclosure are not easily damaged.

Abstract: A compressor (100) comprises a compressor body (10), a pipe (20) connected to the compressor body (10), and an acoustic cover disposed so as to surround the compressor body (10). The acoustic cover (30) has an insertion hole (31) through which the pipe (20) is inserted while being in close contact with the pipe (20), and an inner surface (30A) of the acoustic cover has a shape that traces an outer surface (10A) of the compressor body (10). Due to this configuration, it is possible to reduce the size and the weight of the acoustic cover (30), and by using the acoustic cover (30) with a simpler structure, it is possible to reduce the noise of the compressor (100) of this automobile air conditioning device.

Abstract: A wheel for a vehicle includes a plurality of Helmholtz resonators each including an auxiliary air chamber communicating with a tire air chamber through a communication hole. The Helmholtz resonators include one or more first Helmholtz resonators set to have a silencing characteristic for a first-order resonance frequency of air column resonance noise in the tire air chamber, and one or more second Helmholtz resonators set to have a silencing characteristic for a second-order or higher-order resonance frequency of the air column resonance noise.

Abstract: A freestanding booth comprising upstanding peripheral walls, a roof and a base upon which the booth stands in use, one of the walls defining an opening that is closed by a door, wherein the base extends along a basal edge of a first of the walls, the first wall being fixed to the base via a first levelling assembly, the first levelling assembly comprising a first height adjustment mechanism and a second height adjustment mechanism that are spaced apart from one another in a longitudinal direction of the basal edge of the first wall and are independently adjustable for altering an angle of the basal edge of the first wall relative to the ground.

Abstract: Provided is a speaker box, including a housing having receiving space, a sounding unit received in the housing, and a solder terminal electrically connecting the sounding unit to an external circuit. The housing includes a plastic member and a reinforced rigid body fixed to the plastic member by injection molding. The plastic member includes a bottom wall connected to the reinforced rigid body, a blocking wall connected to the bottom wall, and an enclosure extending from the bottom wall away from the reinforced rigid body. The solder terminal includes a main body portion, first and second electrical connection portions. The enclosure is separated from the blocking wall by a distance and encloses the main body portion. The enclosure and the reinforced rigid body are bonded by glue. The speaker box has low costs, simple assembly and high assembly stability.

Abstract: A soundproofing coating with a cellular structure having several structures connected in a transverse direction, each formed by connecting a first longitudinal strip with a second longitudinal strip. Each structure has, successively in the longitudinal direction, 1) a first cavity, the cross-section of which narrows gradually in the thickness of the coating until it closes, 2) a first connection of two walls, respectively of the first strip and the second strip, in contact with each other over part of the thickness of the coating, which provides a passage between the first cavity and a second cavity that thus form a Helmholtz resonator, 3) the second cavity, the cross-section of which gradually increases in the thickness of the coating and which is closed by a closing sheet, and 4) a second connection of two walls.

Abstract: In a soundproof structure body including a tubular tube body having an opening portion, and a resonance type soundproof structure, in which a phase difference ?, at an upstream of the resonance type soundproof structure, between a reflected wave in the resonance type soundproof structure and a reflected wave of a transmitted wave transmitted through the resonance type soundproof structure and reflected by the opening portion satisfies Inequation |???|??/3 with respect to a resonance frequency of the resonance type soundproof structure. This soundproof structure body can effectively offset a reflected wave from a resonance type soundproof structure body by opening end reflection by appropriately specifying positions of the resonance type soundproof structure and the opening end portion of a duct, a tube line, or the like to improve an absorbance of a single resonance type soundproof structure.

Abstract: A speaker grill includes a diffusion plate, a base, and a support portion. The diffusion plate forms an opening facing in a sound-emitting direction of a speaker and that is arranged on an outer side of the opening. The base supports the diffusion plate at an outer circumference thereof. The support portion is provided at a front surface of the diffusion plate in the sound-emitting direction, having a support surface that covers at least a portion of the front surface of the diffusion plate, and having a plurality of partition walls forming slits in the sound-emitting direction. The support surface forms a virtual surface covers an outer surface of the base.

Abstract: A resistive skin shell for an acoustic panel or inner wall of an aircraft air intake, comprising an alternation, in a transverse direction, of perforated metal bands and of composite solid bands extending in a longitudinal direction. The perforated metal bands and the composite solid bands form a smooth outer face configured to be in contact with an aerodynamic stream, and a crenelated inner face. The composite solid bands have a thickness greater than the perforated metal bands. Since the perforations are provided in metal bands, which are intrinsically resistant to wear and erosion, the future proofing of the acoustic performance of the resistive skin is guaranteed. Since the composite solid bands, which are thicker, can ensure the mechanical strength of the skin, the thickness of the perforated metal bands can be reduced, allowing perforations with dimensions that are also reduced, having a lower impact on drag.

Abstract: A suppressor for firearms, comprising: a casing, comprising; a first end cap, an elongated hollow member, and an second end cap, an upstream disk secured in place between the first end cap and the elongated hollow member; a first hollow diffuser tube having a first end and a second end and a plurality of openings distal to the first end; a second hollow diffuser tube having a first end and a second end and a plurality of openings distal to the first end; and a downstream disk, wherein the disk has a centric opening.