Two distinct fields of research into robust speech recognition are the use of microphone arrays for signal enhancement and the use of independent frequency sub-band models for robust recognition. In this article, we propose and investigate the integration of these two techniques on two different levels. First, a broad-band beamforming microphone array allows for natural integration with sub-band speech recognition as the beamformer is implemented as a combination of band-limited sub-arrays.

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... er than recombining the sub-array outputs to give a single enhanced output, we fuse the output of separate hidden Markov models trained on each sub-array frequency band. Second, a dynamic sub-band weighting algorithm is proposed in which the cross-and autospectral densities of the microphone inputs are used to estimate the reliability of each frequency band. The proposed multi-channel sub-band system is evaluated on an isolated digit recognition task and compared to both a standard full-band microphone array system and a single channel sub-band system. Iain A. McCowan received the B. Eng(Hons) and B. InfoTech degrees from the Queensland University of Technology, Brisbane, in 1996. In February 1998 he joined the Research Concentration in Speech, Audio and Video Technology at the Queensland University of Technology where he is currently completing his Ph.D. His main research interests are in the fields of robust speech recognition and speech enhancement using microphone arrays. Mr McCowan is a student member of the Institute of Electrical and Electronic Engineers. Sridha Sridharan obtained his B.Sc. (Electrical Engineering) and M.Sc. (Communication Engineering) from the University of Manchester