Variations in articulatory kinematics with changes in speech task

By S.M. Tasko and M.D. McClean


            Studies of normal and disordered articulatory movement often rely on the use of short, simple speech tasks.  However, the severity of speech disorders such as stuttering and dysarthria can be observed to vary markedly with speech task.  Understanding task-related variations in articulatory kinematic behavior may allow for an improved understanding of normal and disordered speech motor behavior under varying communication contexts.  This study evaluated how orofacial kinematic behavior varies as a function of speaking task in a group of fifteen healthy male speakers.  A simple, nonsense citation task, and an oral reading task were compared.  Average peak speed, distance and duration of speech-related movement of the upper lip, lower lip, tongue blade and mandible were derived and analyzed.  Across all four articulators, speakers exhibited reduced average peak speed, distance and duration of movement for the oral reading task as compared to the citation task.  However, a task-by-articulator interaction indicates that the degree of reduction was not consistent across the articulators.  Finally, for the lower lip and mandible, two measures (i.e. peak speed and distance) were significantly correlated across the two tasks, suggesting that the speakers varied kinematic behavior for each task in systematic ways.