A sound reducer (10) has a housing (14) with a housing wall bounding an interior space (141). The housing wall has a mantle (142) extending longitudinally along a housing axis. Two end walls (143) are transverse to the housing axis. A main tube (12) extends through the interior space (141) and has a first and second ends (121). Windows (22) are formed as tube wall openings within the interior space (141). The first end (121) of the main tube (12) is fixed at a first passage (18a) through the housing wall, and the second end (122) of the main tube (12) is fixed at a second passage (18b) through the housing wall. At least the second passage (18b) passes eccentrically through one of the end walls (143). The main tube (12) is curved in a main plane and the first passage (18a) passes through the mantle (142).

A method of using an acoustic resonator including receiving at a first stage of a resonator an incoming acoustic wave. The method further includes resonating the incoming wave with a flexible membrane, a taper of the flexible membrane, and a cavity of a first stage, thereby producing synergistic effect on a resulting acoustic resonance. Additionally, the method includes transforming an acoustic energy associated with the incoming acoustic wave into an elastic energy, wherein the elastic energy is channeled through the flexible membrane, thereby reducing an intensity of the incoming acoustic wave and resulting in a first reduced incoming acoustic wave. Further the method includes transferring the first reduced incoming acoustic wave through a hole of a neck of the flexible membrane. The method also includes transferring a first pressure wave caused by a perturbation in the flexible membrane into a second stage, thereby producing a second acoustic wave.

A silencer assembly especially designed for attachment to the exhaust port of vacuum pumps and which adapts to the pumps pressure changes to regulate the outlet flow. The silencer features a perforated housing having an inner channel which connects to the discharge port of the vacuum pump and a valve assembly having a spring-loaded ball for dynamically regulating the fluid flow through the perforated housing. Once the pressure of the flow from the pump is high enough to compress a spring by pushing on a rubber ball which acts as a valve, a channel opens inside the silencer and the air can be vented through the radially distributed perforations on the housing. As the air escapes, the noise caused by the flow is reduced.

A noise damper for a compressed-air system, for a brake system of a utility vehicle, including: a housing having an inlet channel for a compressed-air stream and with a chamber for accommodating sound-damping material, in which the inlet channel and the chamber are separated, perpendicularly with respect to the compressed-air stream, by a separating plate which is closed in a central region and which, in an outer peripheral region of the compressed-air stream, has multiple openings for introducing the compressed air directly into the chamber. Also described are a related pneumatic brake system and method.

The present invention relates to a hose arrangement (100) for creating a bubble curtain (BS) in bodies of water, comprising at least one air hose (4) including an interior space (4b) enclosed by a wall (4a), where a perforation (9) consisting of individual punctures (9a) is introduced in the wall (4a) at least in an upper, first circumferential area (B1), from which air can be discharged, when the interior space (4b) is pressurized, for creating a bubble curtain (BC) extending in the longitudinal direction (X) of the air hose (4), and a ballast receptacle (20) including a receiving area (8) extending in the longitudinal direction (X), in which an elongates ballast element (21) is received.

The invention provides that the air hose (4) is jacketed by a support sheath (10) including material bars (10a) and intermediate openings (10b), the air hose (4) being connected in a connecting area (15) via the support sheath (10) to the ballast receptacle (20), and the openings (10b) being positioned at least in the first circumferential area (B1) of the air hose (4) so as to allow air to be discharged from the perforation (9) in the air hose (4).

An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Disclosed is a noise suppressor for use inside a nozzle and adjacent a nozzle liner. The suppressor can include an inlet with a cross-sectional area larger than that of the nozzle liner outlet. The suppressor can also have an entrance length with a diverging cross-sectional area, and an exit length extending from the entrance length. By incorporating this geometry, the noise suppressor reduces noise and improves performance of the apparatus in which the suppressor is used.

An object is to provide a silencing system that can achieve both high ventilation performance and high soundproof performance, can silence a plurality of pieces of resonant sound, and has high general-purpose properties since the silencing system does not need to be designed according to a tubular member. In a silencing system where silencers are disposed on a tubular member, the silencers silence sound having a frequency of first resonance of the tubular member, each silencer includes a cavity portion and an opening portion, the opening portions are connected to a sound field space of the first resonance of the tubular member, a conversion mechanism for converting sound energy into thermal energy is disposed in each cavity portion or at a position where the conversion mechanism covers the opening portion, a ratio S.sub.1/S.sub.d of the area S.sub.1 to the area S.sub.d satisfies “0<S.sub.1/S.sub.d<40%” in a case where the area of the opening portion of the silencer is denoted by S.sub.1 and the surface area of an inner wall of the cavity portion is denoted by S.sub.d, and the depth L.sub.d of the cavity portion in the traveling direction of an acoustic wave in the silencer satisfies “0.011×λ<L.sub.d<0.25×λ,” in a case where the wavelength of an acoustic wave at the resonant frequency of the first resonance is denoted by λ.

Disclosed is a noise suppressor for use inside a nozzle and adjacent a nozzle liner. The suppressor can include an inlet with a cross-sectional area larger than that of the nozzle liner outlet. The suppressor can also have an entrance length with a diverging cross-sectional area, and an exit length extending from the entrance length. By incorporating this geometry, the noise suppressor reduces noise and improves performance of the apparatus in which the suppressor is used.

A space-saving broadband resonator configured to install within and utilize inner space of other components and includes a resonator insert having a tubular pipe elongated along a central axis, the tubular pipe having a circumferential outer wall having a plurality of perforation holes spaced apart and extending radially through the circumferential outer wall. An interior of the tubular pipe forms a gas flow duct. A plurality of annular disk-shaped walls provided on and projecting radially outwardly from the tubular pipe. Adjacent annular disk-shaped walls spaced axially part from each other define resonator chambers therebetween. A bell mouth is formed at the second axial end of the tubular pipe, the bell mouth flared radially outwardly.