1. A noise reduction system including an audio-visual user interface therein for combining visual features extracted from a digital video sequence with audio features extracted from an analog audio sequence including background noise in an environment of a speaker, said noise reduction system comprising: audio sequence detection means for detecting said analog audio sequence; audio feature extraction and analysis means for analyzing said analog audio sequence and extracting said audio features therefrom; video sequence detection means for detecting said video sequence; visual feature extraction and analysis means for analyzing the detected video sequence and extracting said visual features therefrom; a noise reduction circuit configured to separate a speaker's voice from said background noise based on a combination of derived speech characteristics and configured to output a speech activity indication signal comprising a combination of speech activity estimates supplied by said audio feature extraction and analysis means and said visual feature extraction and analysis means; and a multi-channel acoustic echo cancellation unit configured to perform a near-end speaker detection and double-talk detection algorithm based on the speech characteristics derived by said audio feature extraction and analysis means and said visual feature extraction and analysis means.