11.1. Introduction

The title of this chapter is an (imperfect) plagiarism. In November 1996, during the ICSLP Conference in Philadelphia, a special session was organized by Lynne Bernstein and Christian Beno t. It was entitled: "The Senses of Speech Perception", and was introduced with the following foreword: "For speech perception by humans or machines, three senses are better than one" [BER 96].

Two years later in 1998, a summer school was organized in Grenoble and we asked Christian Beno t to make a presentation on the theme of "Multimodality". However, fate dictated otherwise. So let us quote from Christian, as a furtive tribute to his scientific heritage other tributes have been, and will doubtless be paid to him on a much wider scale a few of the phrases he was gifted enough to invent for promoting and developing this domain, to which he has brought so much; in brief, to "make speech visible as much as possible".

"The bimodality of speech is at the center of a wide fundamental research area aiming at better understanding how human beings speak and coordinate the command of half a dozen articulators, a fraction of which are entirely or partly visible. In this respect, bimodality is at a scientific crossroad, where phoneticians, psychologists and engineers converge. It is also one of the mainstays of speech-impaired rehabilitation and foreign language teaching. Finally, it is the basis for a number of applications in the cartoon...