Modeling of VoIP Conversational Speech in Noisy Environment

This paper proposes the voice over IP (VoIP) traffic models, which include the effect of noisy environment. The proposed models are based on the traffic data measured from the operating IP network of Telephone Organization of Thailand (TOT) Corporation. It was found that the observed distributions of talkspurt and silent durations considerably differ from the standard model (ITU-T P.59). It is proposed that a new state "long burst" representing the background noise at the talker\´s place, is added into the model based on continuous-time Markov process. The other two states, "normal speech" and "long silence", represent the normal behavior of the VoIP user. If background noise occurs during the speech, the model is classified as "noisy speech" otherwise as "noiseless speech". In the observed cases, the data rate of "noisy speech" is about 64% bigger than the data rate of "noiseless speech".