VAD Techniques for Real-Time Speech Transmission on the Internet

We discuss techniques for Voice Activity Detection (VAD) for Voice over Internet Protocol (VoIP). VAD aids in reducing bandwidth requirement of a voice session thereby using bandwidth efficiently. Such a scheme would be implemented in the application Layer. Thus the VAD is independent of the lower layers in the network stack [3]. In this paper, we compare four time-domain VAD algorithms in terms of speech quality, compression level and computational complexity. A comparison of the relative merits and demerits along with the subjective quality of speech after pruning of silence periods is presented for all the algorithms. A quantitative measurement of speech quality for different algorithms is also presented.