VAD for VoIP Using Cepstrum

As telephony services are being supported on Internet the focus is now on multiplexing many speech streams by exploiting the speech characteristics. The multiplexing gain is an important factor when applications such as teleconference service are ported on to the Internet. Here we discuss Voice Activity Detection (VAD) for Voice over Internet Protocol (VoIP) based on Cepstrum. VAD aids in saving bandwidth of a voice session. Such a scheme would be implemented in the application layer thus VAD is independent of the lower layers. The standard codecs would inherently have the VAD algorithms to reduce the bandwidth. However they are costly and computationally complex. In this paper, we compare the quality of speech, level of compression and computational complexity of our method of Cepstrum based VAD with the standard GSM and ITU-T G.729 codecs. Bandwidth reduction is achieved by not transmitting the non-speech packets. Our algorithm adapts to the varying background noise.