Frequencies covered by noise cancellation
On 6/7/2009 10:04 PM Richard Crowley spake thus:
David Nebenzahl wrote:
Mr.T spake thus:
and reinject a perfectly matched inverted copy in exactly the same
spot,
Trivially easy, no? A simple phase inverter oughta do the trick.
No. Because it will almost instantly turn into a closed-loop
feedback oscillator and likely deafen the wearer. If it were
as easy as simple signal inversion, we would have had noise
cancelling headphones decades sooner.
Hmm; that seems counterintuitive. Not disputing you, but I thought that
only positive (i.e., same-phase) signals would cause that kind of
feedback. An inverted signal should (nearly) cancel the original signal,
n'est-ce pas? What am I missing here?
--
Found--the gene that causes belief in genetic determinism
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