Relationship between kinematics, F2 slope and speech intelligibility in dysarthria due to cerebral palsy.

A multimodal approach combining acoustics, intelligibility ratings, articulography and surface electromyography was used to examine the characteristics of dysarthria due to cerebral palsy (CP). CV syllables were studied by obtaining the slope of F2 transition during the diphthong, tongue-jaw kinematics during the release of the onset consonant, and the related submental muscle activities and relating these measures to speech intelligibility. The results show that larger reductions of F2 slope are correlated with lower intelligibility in CP-related dysarthria. Among the three speakers with CP, the speaker with the lowest F2 slope and intelligibility showed smallest tongue release movement and largest jaw opening movement. The other two speakers with CP were comparable in the amplitude and velocity of tongue movements, but one speaker had abnormally prolonged jaw movement. The tongue-jaw coordination pattern found in the speakers with CP could be either compensatory or subject to an incompletely developed oromotor control system.