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From: marcum@nescorna.UUCP
Newsgroups: rec.aviation,sci.electronics,rec.audio
Subject: Re: Noise-cancelling microphone
Message-ID: <19343@sun.uucp>
Date: Wed, 20-May-87 13:50:22 EDT
Article-I.D.: sun.19343
Posted: Wed May 20 13:50:22 1987
Date-Received: Fri, 22-May-87 01:09:04 EDT
References: <1027@mips.UUCP>
Sender: news@sun.uucp
Reply-To: marcum@sun.UUCP (Alan M. Marcum)
Organization: Sun Microsystems, Mountain View
Lines: 16
Xref: utgpu rec.aviation:1299 sci.electronics:634 rec.audio:1412

In <1027@mips.UUCP> mark@mips.UUCP (Mark G. Johnson) wrote:
> ...noise-cancellation system for military pilots' helmets....
> The new system puts a microphone in each earcup, and uses the resulting
> signal to measure the "error" at the pilot's ear [error == signal at ear
> minus signal from radio] and thus cancel much of the ambient noise
> (about 30 dB as I recall)....

I read about an experimental system Bose (yes, the speaker folks) was
building, in, I think, _Aviation Consumer_.  It was an active noise-
cancelling system, much as Mark describes.  It is apparently VERY
comfortable.  Also, even without the magic black box the headset did
an excellent job of noise attenuation.


Alan M. Marcum				Sun Microsystems, Technical Consulting
marcum@nescorna.Sun.COM			Mountain View, California