VoIP echo suppression in critical environments

VoIP communication is increasingly widespread on the global Net. However, VoIP voice quality suffers in highly non-isochronous environments showing high RTT variance. In order to alleviate this quality loss, many algorithms have been proposed to recognize and eliminate acoustic echo and noise. In this paper we analyze the performance of some echo cancellation algorithms in critically non-isochronous environments, showing that a PBEC (Packet-based Echo Canceller) approach is effective provided that the size of the packets taken into account remains above a threshold. The joint adoption of PBEC and of an advanced Jitter Buffer is also discussed.