The objectives of the research include: a) determining the physiological characteristics of normal speech motor control; b) understanding how this physiology is altered in selected speech disorders; and c) developing and evaluating new treatments for speech disorders. a) A replication of Tuller et al., demonstrated that the correlations between lip and jaw movement durations during speech could be largely accounted for by the statistical artifact of correlating a part with a whole. The timing interactions between the lip and jaw did not differ between meaningful and nonsense speech at fast and slow rates. A study of the activation of each of the 5 mandibular muscles during simple jaw movements in 6 different directions demonstrated that the lateral pterygoid had a higher percent of maximum activation during lateral movement to the opposite side than during jaw opening. The changes in air pressure and air flow in normal speakers during fluency evoking conditions for stutterers (delayed auditory feedback, making, choral reading and metronome) were found to differ across conditions. Different types of physiologic changes in speech production may account for fluency changes in these conditions. b) Experimental studies of speech planning are continuing in stuttering, Parkinson's disease, cerebellar degeneration and normal controls. c) Unilateral thyroarytenoid botulinum toxin injections significantly reduced the percent of speech which was dysfluent and the number of word and phrase repetitions in stutterers' speech. The effects of botulinum toxin injections for the treatment of oral-lingual_dyskinesia/dystonia is continuing with significant speech improvements in 7 of 9 cases which persist without reinjection in 30% and are being investigated further.