yes,i find it also not an absurd question.
I had build a loop machine, and i did want to phase cancel the sound is coming out of the speakers to be able recording and play again new stuff over that loop in "realtime" (overdubbing). But as far as i understand it is a really complex thing to do so as chuck allready mentioned. But someone build allready a kind of "feedback canceller" or is it simply not possible in the real world?
Like, it's the best way simply EQ'ing your Soundsystem to have the best result?

all the best,
moritz

On Mon, Feb 23, 2009 at 7:19 PM, Charles Henry <czhenry@gmail.com> wrote:
Hi, yohannes

No, it's not absurd.  Tell us a little bit more about your
application.  I am out of the project game for now, but have some long
term goals for solving this sort of problem.

For example, you send a sound out your speakers.  You want to recieve
a new sound from the room on microphone that is not the sound coming
from the speakers.

This becomes a system identification problem.  You need to find the
delay between the speakers and microphone and the transfer function (a
filter) between speakers and mic.  Then, you digitally apply the
filter and delay to your signals as they would be played and subtract
that copy from the signal received by the mic.

Chuck



On Mon, Feb 23, 2009 at 4:02 PM, yohannes <THIS_IS_POP@web.de> wrote:
> hello everybody,
>
> maybe sounds absurd:
>
> is it possible to cancel an whole signal of an mic input through
> phase-canceling?
>
> if yes, how can i do dat in pd?
>
>
>
> thanks a lot, yohannes
>
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