Book excerpt: Man-machine communication is presently undergoing an important evolution which is influenced both by technological advances and by the progress made in various fields such as signal processing, pattern recognition and artificial intelligence. This book emphasizes relevant aspects of man-machine dialogue by voice (acoustic-phonetic decoding, multi-speaker aspects, dialogue architectures, etc.) and presents analogies with the related fields of computer vision and natural language processing. It also introduces the fundamentals of knowledge-based and expert systems which are widely used in this field. The book is the result of an interdisciplinary collaboration of international experts who worked together for an advanced course sponsored by the Commission of the European Communities and Institut National de Recherche en Informatique et en Automatique. The course was held in Paris in May 1985.