[Speex-dev] Echo Cancellation

Shana Cooke (Gitnick) scooke at viack.com
Mon Aug 23 12:36:29 PDT 2004



I am testing speex 1.1.6's echo canceller. I am using testecho.c, with a
few modifications to get it to run on Windows. 

My problem is that I am unable to get the echo cancellation to work
correctly. I am working on an audio conferencing software, and one issue
we have is sometimes the microphone picks up what is being played
through the headset, resulting in an echo of the other person who is
talking. In order to test this scenario through the echo canceller, I am
running two samples through it. The first is the signal I want to clean
- it is my husband talking, with an echo of myself talking. The second
sample is the reference sample - it is just myself talking. (I used the
second sample to create the first, so it is the exact same wav, with my
husband's speaking placed on top of it.)


The result has my husband speaking clearly, but the echo of myself
talking is garbled and sounds like the Borg Hive from Star Trek. It's
more distracting than the original signal was. I have tried introducing
delays to my echo, but it does not help the signal to become clearer. 


I think I am doing something wrong, but I am not sure what. I notice you
are using two samples - play.sw and ref.sw - which are not included in
the source. What do they sound like? Is there a place one can pick up
these files? Is this echo cancellation designed more for musical tones
instead of actual echoes of speech? I know this is experimental and I
feel I may be using it in the wrong way.


If you want, I can email my samples and the resulting output.


Thank you for your support and for a great product,



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