Voice activity detection for cellular networks

Algorithms for voice activity detection in the presence of vehicular noise and babble noise are presented. The voice activity detector (VAD) designed for vehicular noise is an improvement upon the VAD adopted for the discontinuous transmission (DTX) mode of the GSM standard, and performs significantly better at low SNR levels. Work on a VAD that is suited for the babble noise environment is also briefly mentioned, and a scheme for combining the two VADs is proposed.