Conversation detection in ambient telephony

In some speech communication applications such as distributed hands-free telephony it is important that the system can detect the conversational state of a call. This cannot be performed by speech activity only because the captured signal may also contain conversation between two local people, or additional speech noise sources such as speech sounds from a radio or television. In this paper we compare known algorithms and introduce a new algorithm for the real-time detection of active conversation between an incoming caller and a local user. The method is based on the mutual information in speech activity, detection of back-channel speech activity, and statistics of overlapping speech. The proposed method gives over 90% accuracy within one minute observation period which is a clear improvement over the performance of earlier techniques.