A fairing for a power generation machine, the fairing comprising: a first layer comprising a metallic material; a second layer comprising a composite; and a third layer positioned between the first layer and the second layer, the third layer being configured to attenuate acoustic waves over a predetermined frequency range.

A sound absorber unit and a vehicle wheel having a sound absorber device are provided. The sound absorber devices includes at least one sound absorber unit or at least one sound absorber assembly which is composed of a plurality of sound absorber units. The sound absorber unit is constructed into a box body in a hexahedron shape and forms a three-layer Helmholtz resonance sound absorption structure with double holes and single holes combined, and meanwhile, the sound absorber unit or the sound absorber assembly forms a structural resonance sound absorber. The double-absorption wheel air chamber sound resonance function organically combining Helmholtz resonance sound absorption and structural resonance sound absorption can be realized.

An image forming apparatus includes a cartridge unit and a cartridge support member. The cartridge unit includes a photosensitive drum on a surface of which an electrostatic latent image is to be formed. The cartridge support member supports the cartridge unit inside an apparatus main body. The cartridge unit is detachable from the apparatus main body. In a case where the cartridge unit is attached to the apparatus main body, a Helmholtz resonator including a communication portion and including a cavity portion is constituted of the cartridge unit and the cartridge support member. The cartridge unit includes at least a part of the communication portion of the Helmholtz resonator.

The invention relates to a damper for reducing pulsations in a gas turbine, which includes an enclosure, a main neck extending from the enclosure, a spacer plate disposed in the enclosure to separate the enclosure into a first cavity and a second cavity and an inner neck with a first end and a second end, extending through the spacer plate to interconnect the first cavity and the second cavity. The first end of the inner neck remains in the first cavity and the second end remains in the second cavity. A flow deflecting member is disposed proximate the second end of the inner neck to deflect a flow passing through the inner neck. With the solution of the present invention, as a damper according to embodiments of the present invention operates, flow field hence damping characteristic in the second cavity constant regardless the adjustment of the spacer plate in the enclosure.

The invention relates to a damper for reducing pulsations in a gas turbine, which includes an enclosure, a main neck extending from the enclosure, a spacer plate disposed in the enclosure to separate the enclosure into a first cavity and a second cavity and an inner neck with a first end and a second end, extending through the spacer plate to interconnect the first cavity and the second cavity. The first end of the inner neck remains in the first cavity and the second end remains in the second cavity. A flow deflecting member is disposed proximate the second end of the inner neck to deflect a flow passing through the inner neck. With the solution of the present invention, as a damper according to embodiments of the present invention operates, flow field hence damping characteristic in the second cavity constant regardless the adjustment of the spacer plate in the enclosure.

The invention relates to a damper for reducing pulsations in a gas turbine, which includes an enclosure, a main neck extending from the enclosure, a spacer plate disposed in the enclosure to separate the enclosure into a first cavity and a second cavity and an inner neck with a first end and a second end, extending through the spacer plate to interconnect the first cavity and the second cavity. The first end of the inner neck remains in the first cavity and the second end remains in the second cavity. A flow deflecting member is disposed proximate the second end of the inner neck to deflect a flow passing through the inner neck. With the solution of the present invention, as a damper according to embodiments of the present invention operates, flow field hence damping characteristic in the second cavity constant regardless the adjustment of the spacer plate in the enclosure.

An acoustic device comprising: an enclosure defining an acoustic port and an acoustic pathway between the acoustic port and a transducer coupled to the enclosure; and an array of attenuators acoustically coupled to the acoustic pathway to absorb ultrasonic acoustic waves.

An ear canal earpiece comprising an electroacoustic sound transducer, a first sound guide unit for guiding the sound from the electroacoustic sound transducer, a second sound guide unit for prolonging the first sound guide unit, a third sound guide unit whose outside contour is matched to an inside contour of an ear canal of a user and which surrounds the second sound guide unit, and a sound wall in the region of the second sound guide unit, wherein the sound wall extends between the second and third sound guide units.

A noise reducing sound reproduction system and method is disclosed, in which an input signal is supplied to a loudspeaker by which it is acoustically radiated. The signal radiated by the loudspeaker is received by a microphone that is acoustically coupled to the loudspeaker via a secondary path and that provides a microphone output signal. The microphone output signal may be subtracted from a useful-signal to generate a filter input signal. The filter input signal may be filtered in an active noise reduction filter to generate an error signal. The useful-signal may be subtracted from the error signal to generate the loudspeaker input signal, and the useful-signal may be filtered by one or more low-pass filters prior to subtraction from the microphone output signal.

An acoustic device comprising: an enclosure defining an acoustic port and an acoustic pathway between the acoustic port and a transducer coupled to the enclosure; and an array of attenuators acoustically coupled to the acoustic pathway to absorb ultrasonic acoustic waves.