[Speex-dev] AEC strangest behavior

Anton A. Shpakovsky saa at tomsksoft.com
Tue Mar 16 21:41:20 PDT 2010

Hi again. I've tried turning off one of the speakers, played with
polarity of the speakers - no effect. 

I cannot say that echo is not removed at all - I definitely hear the
distortion of the echo but it still remains as an unpleasant 

"robo-voice" in the background. 

Is the speakers' volume level crucial for speex AEC, or it can
successfully adapt? I just can't understand why does it happening?

Attempts to use testecho.exe on not-working dumps were unsuccessful even
when I played with the signal delay values (it's not more than 10-20 ms,
sometimes even less), volume levels...

I will appreciate if somebody tries to check my dumps, that are still



Thanks, Anton.





From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org] On
Behalf Of Greger Burman
Sent: Monday, March 15, 2010 6:16 PM
To: speex-dev at xiph.org
Subject: Re: [Speex-dev] AEC strangest behavior


One thing I can think of is if you are using two or more speakers. If
the speakers are not at the exact same distance from the mic, you will
get more than one echo. AEC can not handle that. Try disconnecting all
but one speaker and see if it makes any difference.


2010/3/15 Anton A. Shpakovsky <saa at tomsksoft.com
<mailto:saa at tomsksoft.com> >


I have the following situation. AEC is used in network chat software 

over DirectSound API. Echo and reference signals are almost aligned 

(delay is no more than 30ms). When echo is emulated in notebook 

(built-in speakers + mic) everything goes fine and echo is cancelled. 

But when configuration includes stand-alone speakers and mic no echo is 

removed. Audio is in 22050 hz at 16 bit mono format, number of samples 

to process were 441 and tail was used 4096.


Dumps are here:

nb_*** - working configuration (notebook)

sa_*** - standalone speakers with no echo removed


Can it be because of differences in fixed and arbitrary acoustic

I will appreciate any of your advises or thoughts.




Anton A. Shpakovsky

Multimedia Software Developer


Speex-dev mailing list
Speex-dev at xiph.org <mailto:Speex-dev at xiph.org> 


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.xiph.org/pipermail/speex-dev/attachments/20100317/637df845/attachment.htm 

More information about the Speex-dev mailing list