[PD] feedback detection

[hans at eds.org]

This isn't a standard feedback suppression system that I am after.  I  
want to be able to play with the feedback while having the ability to  
prevent it from taking over.  Its part of an interactive installation  
I am working on, the next generation of this:

http://at.or.at/hans/swirler

The autocorrelation stuff sounds interesting, plus I just found Ed  
Kelly's [peakit~], which gives amplitude info of FFT channels.

.hc


On Jul 31, 2006, at 10:23 AM, padawan12 wrote:

>
> Feeback tends toward periodicity at 1/t for a delay of t
> so you could do an autocorrelation (expensive - does Pd
> have an object to help with that?) of te feedback signal
> to look for it. Since you know the frequency in advance
> a simple bp filter is more effective. Not sure what you mean by
> "dominant" part. If gain is greater than unity then it will
> eventually be, but if you think of a Karplus=Strong it is by
> definition once the excitory signal has vanished. Am I understanding
> your question(?) if I say the best way is to simply monitor the  
> amplitude
> , because if G>1 the amplitude will *always* keep growing.
>
> On Sun, 30 Jul 2006 19:07:12 -0400
> Hans-Christoph Steiner <hans at eds.org> wrote:
>
>>
>> Has anyone done anything with trying to detect feedback in a signal?
>> I am not looking so much for feedback suppression techniques, but
>> rather detection techniques.  I am working on a system that has a
>> slow feedback loop.  I want to detect when feedback is the dominant
>> part of the signal, and make the system respond in novel ways.
>>
>> .hc
>>
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