Subject: Re: [linux-audio-dev] sound cancelation with anti-sound
From: Matthew Wishek (matthew_AT_wishek.com)
Date: Thu Apr 04 2002 - 20:11:48 EEST
It may be easier to buy quieter fans, but it could be more fun to try the
following:
http://www.analog.com/library/analogDialogue/archives/34-02/noise/
Matthew
----- Original Message -----
From: "Maarten de Boer" <mdeboer_AT_iua.upf.es>
To: <linux-audio-dev_AT_music.columbia.edu>
Cc: <iua-linux_AT_iua.upf.es>
Sent: Thursday, April 04, 2002 2:46 AM
Subject: [linux-audio-dev] sound cancelation with anti-sound
> i have been thinking about the following before, and now
> that i read about it on slashdot, and it got me thinking
> a bit more.
>
> the issue is sound cancelation. the article mentioned
> on slashdot,
> http://www.newscientist.com/news/news.jsp?id=ns99992094
> talks about a (very expensive) general approach of
> removing sound with anti-sound.
>
> personally, i am more interested in a very specific
> noise: the noise of the cooling fans in my pc.
>
> i am sure it would be possible to have a background
> application running that uses the soundcard (could be
> a cheap one) to do this. the sound of each fan has
> almost constant pitch, and i suppose it is harmonic.
>
> the application should record the noise, analyse it:
> determine the pitch of each fan and seperate the sounds
> of all fans, invert each signal, and play it back.
> this should work reasonably well as long as the pitch
> doesn't change. by reanalising constantly, any changes
> in the sampled signal have the be analyses and added
> to the canceling inverted signal.
>
> the problem is the sound seperation. The application
> should be low on CPU usage, so I guess time domain
> processing is the only option. but we are talking about
> let's say 3 different signals with rather simple content...
>
> any suggestions / remarks?
>
> maarten
>
>
>
>
>
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