Electrical audio signal processing systems and devices – Acoustical noise or sound cancellation – Adjacent ear
Patent
1985-06-14
1987-05-26
Rubinson, Gene Z.
Electrical audio signal processing systems and devices
Acoustical noise or sound cancellation
Adjacent ear
381 94, H04R 128
Patent
active
046691227
ABSTRACT:
Sound in ducts can be reduced by using two cancelling sources spaced along the duct, and in order to reduce reflections upstream of the cancelling sources, sounds from these sources may be arranged to be in phase opposition upstream from the sources at all frequencies. Such an arrangement does not provide cancellation downstream at some frequencies. In the invention sound detected by a microphone is processed to generate a drive signal for a first source which tends to cancel sound in the duct partially, the remainder of the cancellation being provided by a sound source. A delay positioned between the sources is such that sounds from these sources are in phase at all frequencies of interest downstream of the second source.
REFERENCES:
patent: 4044203 (1977-08-01), Swinbanks
patent: 4109108 (1978-08-01), Coxon
patent: 4122303 (1978-10-01), Chaplin
patent: 4171465 (1979-10-01), Swinbanks
patent: 4423289 (1983-12-01), Swinbanks
patent: 4473906 (1984-09-01), Warnaka
patent: 4480333 (1984-10-01), Ross
patent: 4489441 (1984-12-01), Chaplin
patent: 4562589 (1985-12-01), Warnaka
"The Active Control of Low Frequency Sound in a Gas Turbine Compressor Installation", by M. A. Swinbanks, Inter-Noise '82, May 17-19, 1982.
"The Active Control of Sound Propagation in Long Ducts", by M. A. Swinbanks, Journal of Sound and Vibration (1973) 27(3), 411-436.
"An Experimental Study of a Broadband Active Attenuator for Cancellation of Random Noise in Ducts", La Fountaine et al., Journal of Sound and Vibration, (1983) 91(3), 351-362.
National Research Development Corporation
Rubinson Gene Z.
Schroeder L. C.
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