Relating selective brain damage to impairments with voicing contrasts.

Research is reviewed concerning the performance of several neurological groups on the perception and production of voicing contrasts in speech. Patients with cerebellar damage, Parkinson's disease, specific language impairment, Broca's aphasia, apraxia, and Wernicke's aphasia have been reported to be impaired in the perception and articulation of voicing. The types of deficits manifested by these neurologically impaired groups in creating and discriminating voicing contrasts are discussed and the respective contributions of separate neural areas are identified. A model is presented specifying the level of phonemic processing thought to be impaired for each patient group and critical tests of the model's predictions are identified.