Disordered articulatory movements havebeen documented in IPD through kinematicanalysis of jaw movements.57,59–61 On average,jaw movement of individuals with IPD hasbeen reported to be approximately half thesize of the jaw movements observed innondisordered subjects. The reduction in rangeof movement has been attributed to rigidityof the articulatory muscles62; however, this maybe related to a problem with sensorimotorperception and/or scaling of speech and nonspeech movements.9,29,30,58 In contrast toranges of movements, durations of movementsin individuals with IPD have been reported tobe similar to those of healthy individuals.57