Acoustic Echo Cancellation in hostile delay environment

Are there any good techniques for acoustic echo cancellation where the
delay between ref and mic drifts either during a call or between calls?




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On Tuesday, June 16, 2015 at 6:49:45 PM UTC-5, andygough1974 wrote:
> Are there any good techniques for acoustic echo cancellation where the
> delay between ref and mic drifts either during a call or between calls?
> 
> 
> 
> 
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> Posted through http://www.DSPRelated.com

That is the challenge of acoustic echo cancellation. The impulse response as well as the delay is usually dynamic.

This is why adaptive filters are used.  The speed of adaptation must be faster than the speed at which the path is changing. Modern echo-cancelers usually use sub-band techniques where you break up both the ref signal and the mic signal into some small number of bands and adapt each one seperately. That speeds up the adaptation for reasons that are a little too complicated to write here. 

Bob