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From: jpexg@mit-hermes.AI.MIT.EDU (John Purbrick)
Newsgroups: rec.aviation,sci.electronics,rec.audio
Subject: Re: Noise-cancelling microphone
Message-ID: <2849@mit-hermes.AI.MIT.EDU>
Date: Fri, 22-May-87 01:48:38 EDT
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Posted: Fri May 22 01:48:38 1987
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Organization: MIT AI Lab, Cambridge, MA
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Regarding noise-cancelling speakers and mikes, there was an article in the
British magazine "New Scientist" a while back about the use of "anti-noise"
near large sources of acoustic noise like stationary gas turbine installations.
The idea was to put a microphone some way from the device and drive a speaker
adjacent to the device; an electronic system would try to null out the
resultant signal as measured at the mike. As I recall the system was claimed
to work fairly well, but I don't recall the db figures or how they solved
the obvious problem of delay from the noise sources to the mike.