From: John Woodgate
Subject: Re: Sound cancellation technology?
Date: Thu, 26 Dec 2002 08:50:23 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 26 Dec 2002 09:41:35 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Bill Shymanski
) about 'Sound cancellation technology?', on Wed, 25 Dec 2002:
>OK, maybe I've got a bug in my bonnet this month. Anyway, while waiting
>for an impulse test to be
>set up on a large power transformer, I was reading a draft IEEE guide
>covering noise suppression
>techniques to be used with large power transformers. One of the methods
>proposed is active
>noise cancellation, which apparently gives 10 to 15 dB of suppression of
>the "tonal" hum associated
>with power transformers. The draft guide seems to indicate that this
>technique is commercially
It is, and it's possible to do better than 15 dB within a small volume.
The Lotus car company has done a LOT of work on this.
>Other places I've read of sound cancellation being used is aboard
>aircraft; some of the commuter jets
>has speakers throgh the cabin to hold down the noise.
That is also correct.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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