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From: MJB@cup.portal.com (Martin J Brown-Jr)
Newsgroups: sci.physics,sci.math,sci.electronics
Subject: Re: noise cancellation
Message-ID: <16067@cup.portal.com>
Date: 21 Mar 89 06:39:32 GMT
References: <723@wucs1.wustl.edu> <7260@fluke.COM> <1290@wpi.wpi.edu> <7973@ihlpf.ATT.COM> <7714@polya.Stanford.EDU> <15890@cup.portal.com> <633@ivucsb.UUCP>
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In my initial posting on this subject, I mentioned that a U.S. car company
used the stereo in some of its cars to cancel out road noise, using white
noise out of phase. Todd (Day?) wondered "out of phase to what"? I as 
remember(?), analysis of the road noise rumbling was done, and this noise
was cancelled by having the stereo generate noise(?) of the same frequency,
as far as the stereo could generate, but out of phase with the noise. If I am
somewhat hazy on this, sorry. This isn't my field, and the first posting was 
done in order to provide another source of info for those who wished to 
explore more fully?
                               - MJB -