Electrical audio signal processing systems and devices – Acoustical noise or sound cancellation – Within cabin or compartment of vehicle
Patent
1996-12-19
2000-03-21
Chang, Vivian
Electrical audio signal processing systems and devices
Acoustical noise or sound cancellation
Within cabin or compartment of vehicle
381 711, A61F 1106
Patent
active
060411252
ABSTRACT:
An active acoustic wall has sound-pressure detectors provided within respective cells so that a detected signal acts to oscillate an oscillation plate in the cell. A porous material on a surface is thereby provided with a high sound absorption coefficient over a wide frequency range. A space between a porous material or a perforated plate 1 on the surface and a back material fixed on a back side is divided into a plurality of sections so as to form cells 10 containing an air layer or a porous sound-absorbing material. Oscillation plates 6 are arranged within respective cells 10 so as to be driven for oscillation by oscillation-plate driving units 5. Sound-pressure detectors 7 are provided close to the porous material 1 in the cell 10 so that a detected signal is inputted to a signal-processing unit 8. The signal processing unit 8 outputs a signal to the driving unit 5 for oscillating the oscillation plate 6 such that an output of the sound-pressure detector is minimized. The sound pressure on the surface of the porous material 1 is minimized at all frequencies. The velocity of particles on the surface becomes large so that the particles are turned into thermal energy, thereby providing a high sound-absorption coefficient.
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Kajii Shinichiro
Nishimura Masaharu
Ohnishi Keizo
Patrick William P.
Yasuda Chiaki
Chang Vivian
Mitsubishi Jukogyo Kabushiki Kaishal
United Technologies Corporation
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