Article View: sci.physics
Article #7712Re: noise cancellation
From: Phil Arellano
Date: Sat, 11 Mar 1989 08:03
Date: Sat, 11 Mar 1989 08:03
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A recent "NASA Tech Brief" contained an article on work done on noise
cancellation techniques applied to engine exhuast muffling. A speaker
enclosure was built around some protion of the exhuast pipe while microphones
were placed around the enclosure. A feedback/amplifier circuit was used to
drive the speaker such that only a slight exhuast noise was produced.
Engine efficiency was improved, as well as noise reduced.
The point is that cyclical sounds can be easily cancelled out if the
cancellation signal was generated at or around the sound generator, or if the
cancellation signal was generated at the ear. Noise cancelling headsets are in
use now by pilots.
phil
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!gatech!rutgers!apple!vsi1!daver!mips!phil From: phil@mips.COM (Phil Arellano) Newsgroups: sci.physics,sci.math,sci.electronics Subject: Re: noise cancellation Message-ID: <15072@electron.mips.COM> Date: 11 Mar 89 08:03:38 GMT References: <723@wucs1.wustl.edu> <4225@watvlsi.waterloo.edu> <1989Mar10.173840.732@utzoo.uucp> Reply-To: phil@mips.COM (Phil Arellano) Organization: MIPS Computer Systems, Sunnyvale, CA Lines: 18