[Speex-dev] About Sampling Rate Correction in acoustic echo cancellation

[Jean-Marc Valin]

Steve Underwood <steveu at coppice.org> a écrit :
> I noticed that the Fraunhofer Institute is now selling a package to
> address echo cancellation when the tx sample rate cannot be trusted to
> exactly match the rx sample rate - primarily in VoIP conferencing
> applications. They say they use the spectral envelope, and disregard the
> phase. That sounds like its not a million miles from the spectral
> subtraction a lot of noise suppression schemes use, and those aren't
> great at getting high levels of suppression. However, they claim very
> high levels of echo suppression. There must be more to what they do than
> the blurb indicates.

It's relatively easy to getting high levels of echo suppression using  
spectral subtraction methods. In fact even half-duplex cheap  
hands-free phones can achieve that. The tricky part is not to distort  
the "local" voice during double-talk. That's the hard part when you  
can't rely on an adaptive filter.

Cheers,

    Jean-Marc