As well as conveying a message in words and sounds, the speech signal carries information about the speaker's own anatomy, physiology, linguistic experience and mental state. These speaker characteristics are found in speech at all levels of description: from the spectral information in the sounds to the choice of words and utterances themselves.

This volume and its companion volume, LNAI 4441, constitute a state-of-the-art survey for the field of speaker classification. They approach the following questions: What characteristics of the speaker become manifest in his or her voice and speaking behavior? Which of them can be inferred from analyzing the acoustic realizations? What can this information be used for? Which methods are the most suitable for diversified problems in this area of research? How should the quality of the results be evaluated?

The 19 contributions to this volume comprise general and overview-like articles that are organized in topical sections on fundamentals, characteristics, applications, methods and features, as well as evaluation.