Smoothing Disjoint Formant Track Boundaries Caused by Waveform Substitution inPacket Voice Communication

摘要

This paper describes a method for smoothing disjoint formant track boundariesthat can arise in packet voice communication. The disjoint boundaries can occur when missing packets are reconstructed using waveform substitution methods. Our algorithm attempts to match formant locations to LPC-poles and then adjusts the pole locations across the boundary to smooth the formants at the boundary. We describe our method for matching formants to poles and our method for adjusting the poles. The LPC residual is not modified. Time domain plots and LPC spectrograms are used to show that the formant track was smoothed. Perceptually subjective listening tests confirm that an improvement in the speech quality is achieved with this method in that it sounds more clear and natural.