Aphasia, dichotic testing and defective hearing.

Cerebral lesions causing aphasia are often found close to auditory areas. The aphasia may therefore sometimes be aggravated by hearing problems, which are concealed by communicative restrictions. Unilateral lesions of the cerebral auditory system influence the functional ear preference disclosed by dichotic tests. For that reason we have examined aphasic patients with recent, initial, unilateral brain infarctions for ear preference with regard to dichotically presented two syllable words. In a consecutive series of 114 patients who could cope with the test, 29 showed signs of an acquired left ear advantage (LEA). All were offered, and 22 accepted a full scale audiological examination including pure tone, speech and phase-audiometry. Nine of these patients showed retrocochlear or central hearing disturbances, which added to their communicative predicaments. The LEA of 11 patients lacked audiological rationales and a compensatory shift of cerebral speech-lateralization cannot be excluded.