[Speex-dev] Speech switching in speakerphone?

Johan Nilsson han at svep.se
Wed Jun 24 02:45:21 PDT 2009

>> I think the residual echo estimation is fairly reliable but I do not know
>> how to use this to improve Pframe and in that way solve our main problem
>> with the gain during near end talk.
> How can you tell that the residual echo estimation is reliable? in any
> case, I suspect that the whole Pframe idea might have to be revised
> (i.e. computing it completely differently or even not having a Pframe at
> all).

My impression when simulating in matlab is that the noise estimate which is
based on the residual echo is correlating well with the far-end activity.

>> Our main problem with the poor reliability during near end talk is what we
>> need to find a solution to now. 
> OK, I'll have to think about it. At this point I'm not sure what to do
> here. If you find anything, I'm definitely interested.

The one idea I have is to have a default gain2 of 0dB and only when the 
residual echo goes high we reduce the gain2. This could be implemented
similar to eq. (3) and (4) in this paper:


The idea would be to use your estimation of the residual echo and noise
But to modify the calculation of the gain2. This would probably offer 
a more robust solution since we do not have to rely on the SNR. However 
we would lose the noise suppression functionality I guess (which probably 
is ok).

Are you familiar with any other RES-algorithm that might be more robust
to weak near-end signals?

Best regards

More information about the Speex-dev mailing list