[Speex-dev] Problems with Speex echo canceller in 1.1.10

wang.zhiping1 at zte.com.cn wang.zhiping1 at zte.com.cn
Thu Jul 28 18:00:49 PDT 2005

Eecho cancellation is used to eliminate the echo which mixed with near end 
speech, while it was occured by far end speech.
It always work like this:
Find the similar speech in near end speech and eliminate it.

In case 1:
Because the there is no echo in near end speech, and the EC module still 
works on it. So a inverse model is been calculated, and a inverse signal 
is produced. In this way , you can hear the far end speech.

In case 2:
Is the NES is produeced by FES? 
Maybe EC can not recognise the speech as human been just because it is 

If you want to check the EC, I think you should prepare a echo path model 
(you can find some typical models on G.168 ). You get a echo signal when 
the model applied on FES.

Once you want a signle talk test, you can use the echo signal as the NES.

If you want to test double talk, you can add the echo signal with another 


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