Frequencies covered by noise cancellation
"Richard Crowley" wrote in message
...
But that's not how noise cancellation works. That method
would merely create acoustic feedback.
You do know the difference between positive and negative feedback
right? *Negative* acoustic feedback is actually what they are trying
to achieve. And Dick specifically said to invert the phase, i.e.
negative feedback.
Easy to do electronically, extraordinarily difficult to do accoustically
at
short wavelengths. That is why modern consumer noise cancelling products
depend on inexpensive DSP. You cannot just take an acoustic signal from a
microphone "invert" it and try to cancel noise with it. You don't have to
take my word for it. Try it for yourself.
Please read what I wrote, I never said it was that simple. I simply said in
practice you are providing negative acoustic feedback.
HOW it is *effectively* achieved is another matter entirely.
MrT.
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