Selective acoustic phonetic impairment and lexical access in an aphasic patient.

The relationship between acoustic-phonetic disturbances and lexical access was explored in an aphasic patient. M.L. had a restricted disturbance of phonemic discrimination that affected the discrimination of voicing contrasts in nonword stimuli. Despite this impairment, her discrimination of voicing contrasts in words and her comprehension of auditorily presented words containing voiced segments was excellent. Performance on lexical decision was impaired: M.L.'s rejection of nonwords was poor and her reaction times and error rates for word stimuli showed a trend toward being influenced by the lexical status (word or nonword) of the item that would be formed by a change in voicing. The results are consistent with a role for a phonemic code in auditory word recognition, coupled with lexical-to-acoustic/phonetic feedback, but are also compatible with the view that other access codes for the Phonological Input Lexicon are also available.