Analysis of lips and jaw multi-peaked velocity curve profiles in the fluent speech of stutterers and nonstutterers

It is well known that changes in the rate of movement of the speech articulators can modify the bell-shaped profile of a typical velocity curve. In this experiment, four stutterers and four nonstutterers produced 10 sequences of /papapapa.../ and 10 of /bababa.../ at comfortable rate, and then at maximal rate. The kinematics of the opening and closing phonetic gestures was investigated using ELITE, a fully automatic, real-time system for 3D kinematic data acquisition. Analyses was performed only on the "dynamic" portion of the curves of the gestures perceived to be fluent, thereby excluding the steady state portions of the movement pattern. For both subjects groups, the comfortable rate condition is associated with a greater number of multi-peaked velocity curves than is the fast condition (most for the upper lip). However, stutterers realize a significantly greater percentage of multi-peaked curves than do nonstutterers.