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Re: Sound Cancellation - Thanks!



On Fri, 3 May 2002, John Mallinckrodt wrote:

That is to say, the process of absorption can be viewed as
"setting up a perfectly cancelling wave."

The same is true of reflection. If you set up an active sound
cancellation circuit with the microphone is near the speaker cone, then
the loudspeaker cone will act like an extremely rigid barrier which
reflects incoming sound. Mirrors work like this too: the electron sea
in the metal layer will vibrate in such a way that it sends out an
opposite wave in line with the incoming wave. The wave that would pass
through the mirror gets cancelled, and the cancellation process causes a
reflected wave to appear.

Sound-cancelling circuit:

http://headwize.com/projects/showproj.php?file=noise_prj.htm

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