Electrical audio signal processing systems and devices – Acoustical noise or sound cancellation – Within duct
Patent
1997-05-02
2000-12-12
Harvey, Minsun Oh
Electrical audio signal processing systems and devices
Acoustical noise or sound cancellation
Within duct
381 711, 381 714, A61F 1106, G10K 1116, H03B 2900
Patent
active
061608920
ABSTRACT:
In the active muffler disclosed herein, a porous flow resistive member defines a wall of a duct carrying a noisy flow, e.g., a jet exhaust. The flow resistive member is characterized by having a flow resistance substantially less than .rho.c, the characteristic impedance of the acoustic medium. Loudspeakers in a chamber on the side of said porous member opposite the duct are actuated to reduce acoustic pressure in the region between the porous member and the loudspeaker, thereby increasing the acoustic flow through the porous member which in turn increases the dissipation of acoustic energy in the duct. The apparatus is particularly effective at low frequencies where a passive dissipative muffler would be of impractical size.
REFERENCES:
patent: 2810449 (1957-10-01), Coleman
patent: 2983790 (1961-05-01), Olson
patent: 3688865 (1972-09-01), Smith
patent: 3710617 (1973-01-01), Andersen
patent: 4044203 (1977-08-01), Swinbanks
patent: 4091892 (1978-05-01), Hehmann et al.
patent: 4100993 (1978-07-01), Feder
patent: 4489441 (1984-12-01), Chaplin
patent: 4665549 (1987-05-01), Eriksson et al.
patent: 4753319 (1988-06-01), Vinciguerra
patent: 5060271 (1991-10-01), Geddes
patent: 5088575 (1992-02-01), Eriksson
patent: 5097923 (1992-03-01), Ziegler et al.
patent: 5119902 (1992-06-01), Geddes
patent: 5257316 (1993-10-01), Takeyama
patent: 5272286 (1993-12-01), Cain
patent: 5511127 (1996-04-01), Warnaka
patent: 5513266 (1996-04-01), Zuroski
D. Guicking et al. "An Active Sound Absorber With Porous Plate", Jul. 1984, vol. 106 Journal of Vibration, Acoustics, Stress, and Reliability in Design, pp. 389-392.
C. J. Radcliffe et al., "Development Of An Active Acoustic Sink (AAS) For Noise Control Applications",DE-vol. 75, Active Control of Vibration and Noise ASME 1994, pp. 43-50.
D. Thenail et al. "Absorption By An Actively Enhanced Material", DE-vol. 75, Active Control of Vibration and Noise ASME 1994, pp. 441-448.
Anderson Floyd E.
BBN Corporation
Harvey Minsun Oh
Suchyta Leonard Charles
Weixel James K.
LandOfFree
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