ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

4pSP4. On the perceptual characteristics of ``speech gestures.''

Rene Carre

Samir Chennoukh

ENST, 46 rue Barrault, Paris, France

Pierre Divenyi

Veterans Affairs Med. Ctr., Martinez, CA

Bjorn Lindblom

Univ. of Stockholm

The notion of ``speech gesture'' or ``phonetic gesture'' has been developed as a theoretical construct during the past few years. For present purposes, the term is specified as a ``phonologically significant task defined on the vocal tract area function.'' A given task generally involves the coordination of the movements of several articulators. It appears reasonable to expect speech gestures to have perceptual characteristics like the following: (a) Within certain limits, the time course of speech gestures is not important; (b) within certain limits, the precise synchronization of two, or more, gestures (e.g., constriction displacement and lip opening) is also unimportant; (c) vowel reduction is a natural consequence of speech gesture characteristics. The commands of the distinctive region model were studied as possible speech gestures. Preliminary tests show, as hypothesized, that there are no significant perceptual differences (a) when the shape of a gestural transition is changed to be linear, quadratic, logarithmic, or cosine; (b) when the time separation between two gestures varies from -30 to +30 ms; (c) when gestural dynamics (transitional rate of change) is kept constant but the target is not reached (because of movement undershoot).