Re: How to Detect Double Talk in Acoustic Echo Canceller | Echo Cancellation

May I ask what does 'near-end signal' means? The signal observed at the output of the microphone (array) consists of 'near-end speech plus signal' and 'echo'. If 'near-end signal' refers to the speech signal from the near-end talker plus any background noise originated at the near-end, step 4 appears to be pretty odd to me, coz there is no way on can observe this signal. There are two ways (maybe I should say three ways) to handle double talk, as I know. One is use a double talk detector and inhibit the adaptation whenever double talk is detected. The second one is to estimate the optimal stepsize (for NLMS) and use that for the adaptation. The third is quite rough, just adapt on an auxiliary filter and copy the filter weights to the main filter (used for cancelling the echo). 'Acoustic echo control: an application of very- high-order adaptive filters' by Christina Breining et. al. (IEEE SP Mag. July 1999) contains some good discussion of this topic. And also chapter 5 of the book 'acoustic signal processing for telecommunication' by Gay and Benesty. --- In echocancel@y..., Tapas Guha Neogi _98007017_ <taps8ue@e...> wrote: > hi all.. > I had worked on a project on acoustic echo cancellation and would like > to share my knowledge in the field with each of you.I had used an > algorithm to detect double talk while using the NLMS algorithm.Though it > worked fine with the NLMS algorithm it didn't perform well with the other > algorithms I had worked on. > The algorithm I had followed was as follows. > 1.determine presence of farend and near end speech by using > appropriate values of SNRs on each side.While chosing the SNR the expected > signal and corresponding noise energy on each side was taken itno > consideration. > 2.set up a counter say cnt. > 3.adapt the filter coefficients only if far end signal present.cnt=cnt > 4.if far end signal and near end signal present than stop > adaptation.cnt=cnt+1. > 5.if cnt > num then increase cnt by a greater factor say 50.dont adapt. > 6.if cnt > highnum then flush all the filter coefficients.restart. > this algorithm worked for me with the NLMS algorithms under certain test > conditions.I dont have a good exposure in this area, so it would be really > adisable to seek advice from more knowledgeable people around.However i > thought I would bring forth my algorithm so that i get feedabcks about > drawbacks that exist in the model.Waiting for your kind feedbacks. > Regards, > Tapas Guha Neogi > Senior Undergraduate, > Electrical Engineering Department, > Indian Institute of Technology,Bombay, > India > On Sat, 11 Aug 2001, Fuliang yin wrote: > > > Hi, > > > > An echo canceller must include the double-talk module. But in acoustic > > echo canceller, the energy of the acoustic echo often is larger than that of > > far-end speech because of effect of power amplifier in TV. This situation > > often occurs in the videoconference system. Can anybody tell me how to > > efficiently detect the double-talk ? Any information (Article, Patent, > > software, resource, etc) will be appreciated. > > > > Thanks > > > > Fuliang Yin > > > > > > > > > > > > _____________________________________ > > > > > > > > > > >

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Discussion Groups | Echo Cancellation | Re: How to Detect Double Talk in Acoustic Echo Canceller

channel equalier doubt? - Author Unknown - Aug 15 5:11:00 2001

Re: How to Detect Double Talk in Acoustic Echo Canceller - Author Unknown - Aug 29 7:23:00 2001