[Speex-dev] AEC gets worse as sample rate increases

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Mon Dec 10 14:11:01 PST 2007

Try using SPEEX_ECHO_SET_SAMPLING_RATE to specify your sampling rate.
Also, don't forget that the tail need to be longer (proportional to the
sampling rate). Last thing, if you use resampling, make sure you use a
decent resampler (the Speex one is fine) because otherwise, any aliasing
left will not be cancelled.


Mihai Balea a écrit :
> Hi all,
> I am attempting to test AEC behavior at various sample rates.
> I ran a little experiment: I recorded a 10 seconds voice clip and the
> resampled at 8000, 11025, 16000, 22050, 24000, 32000, 44100 and 48000.
> I have a small applications that plays a wave file, records whatever
> comes in from the microphone and applies the Speex AEC and preprocessor
> on the input.  It then saves the raw input as well as the processed
> audio to different wave files.  The EC is set up with a tail of about
> 200 ms and the EC sample rate is also set via the speex_echo_ctl
> intreface.  I am also hooking up the EC to the preprocessor for
> additional echo reduction.
> What I observed is that 8K and 11.025K work very well, but the quality
> of the AEC degrades as the sample rate goes up.
> I am wondering if this behavior is normal.  Has anybody tried to run the
> speex AEC at a rate different than 8K? Is there something I should be
> aware of?
> Thanks,
> Mihai
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