In the sound insulation apparatus, a sound wave transmitter configured to transmit sound waves with frequencies including the frequencies of propagation sound waves from a sound source and a sound wave receiver configured to receive the sound waves transmitted from the sound wave transmitter are coupled such that the orientation of a sound wave transmission surface of the sound wave transmitter and the orientation of a sound wave receiving surface of the sound wave receiver intersect each other and one pair set is formed. The one pair set is disposed in plurality such that the sound wave transmission surface of one set is spaced from and opposed to the sound wave receiving surface of another set and a space surrounding the sound source is formed. The sound waves transmitted from each of the sound wave transmitters are mixed with the propagation sound waves.

An airgun moderator employing a stack of acoustic baffles fabricated from fibrous polymeric felt, which degrades in the presence of gunpowder combustion temperatures, thereby providing an effective airgun sound moderator that us ineffective as a firearms silencer.

An airgun moderator employing a stack of acoustic baffles fabricated from fibrous polymeric felt, which degrades in the presence of gunpowder combustion temperatures, thereby providing an effective airgun sound moderator that us ineffective as a firearms silencer.

Disclosed is a precisely controlled microphone acoustic attenuator that lowers the sound pressure level to minimize microphone distortion. The acoustic attenuator also serves as a protective microphone enclosure that reduces exposure to debris as well as environmental humidity and harmful gases.

A surface liner member includes an external wall which is provided with multiple holes, a spacer structure, and tubes which are respectively associated with the holes in the external wall. The surface liner member is intended to be applied to a base surface in order to reduce, by acoustic absorption, an acoustic wave reflected on this base surface. The acoustic absorption efficiency is improved, particularly for frequencies below 500 Hz, by varying the shape of the holes in the external wall such that the ratio of the hole perimeter to the hole area varies. Such a surface liner member may be adapted to form a surface portion of an aircraft engine nacelle, or of a leading edge of an aircraft wing.

A surface liner member includes an external wall which is provided with multiple holes, a spacer structure, and tubes which are respectively associated with the holes in the external wall. The surface liner member is intended to be applied to a base surface in order to reduce, by acoustic absorption, an acoustic wave reflected on this base surface. The acoustic absorption efficiency is improved, particularly for frequencies below 500 Hz, by varying the shape of the holes in the external wall such that the ratio of the hole perimeter to the hole area varies. Such a surface liner member may be adapted to form a surface portion of an aircraft engine nacelle, or of a leading edge of an aircraft wing.

A vibration reduction device having an acoustic meta structure mounted to a vehicle body and configured to block a structure-borne noise transmitted through the vehicle body may include a plurality of unit structures arranged at a predetermined interval therebetween, wherein each of the unit structures includes frame mounted to the vehicle body and configured to separate a predetermined space into a predetermined number of separate sections formed by walls of the frame; and a vibrator formed at a corner portion of each of the separate sections and each of which has a natural frequency to block a vibration transmitted from the vehicle body through the frame.

A vibration reduction device having an acoustic meta structure mounted to a vehicle body and configured to block a structure-borne noise transmitted through the vehicle body may include a plurality of unit structures arranged at a predetermined interval therebetween, wherein each of the unit structures includes frame mounted to the vehicle body and configured to separate a predetermined space into a predetermined number of separate sections formed by walls of the frame; and a vibrator formed at a corner portion of each of the separate sections and each of which has a natural frequency to block a vibration transmitted from the vehicle body through the frame.

A sound isolation assembly comprising: a center ferrule; a top grommet isolator; a bottom grommet isolator; a spring; and a furring channel engagement portion. The sound isolation assembly is configured to engage with a structure and a furring channel, which itself is connected to a ceiling panel, such that the noise passing from one floor to the other is lessened as compared to a control system that does not use the sound isolation assembly. The spring may be steel and the grommet isolators may be rubber or the like, and the combination of the steel spring and grommet isolators reduces noise.

A sound isolation assembly comprising: a center ferrule; a top grommet isolator; a bottom grommet isolator; a spring; and a furring channel engagement portion. The sound isolation assembly is configured to engage with a structure and a furring channel, which itself is connected to a ceiling panel, such that the noise passing from one floor to the other is lessened as compared to a control system that does not use the sound isolation assembly. The spring may be steel and the grommet isolators may be rubber or the like, and the combination of the steel spring and grommet isolators reduces noise.