Hi Marly: Basically You need to compute the Low Band Energy and Fullband Enery, Line Spectral frequencey and Zero Crossing rate. For computing the Voice activity detection for the Input speech of 8khz and 16 bit format. well to compute FBE and LBE please reffer ITU G729 Annex A and B As Far I can Recall FullBand Energy (FBE) = log base 10 (A[0] / 240 (samples)) Low Band Energy (LBE) = 10 * log base 10 (A[0] * h * (Toplize matrix of Auto correalteion cofficent (13 coefficent)) * Transpose of h) / 240) where A[0] = First auto correlation coeffcient, h = Impluse response of 1hz cutoff frequnecy Please do refer the ITU G729 Annex B and Annex A for further clarification Any Doubts Do mail back. HTH Regards Ranjeet Gupta > Anyone can help finding code for g711 VAD calculation/energy >calculation ? > >Many thanks > >Marly > > > > > > >