Abstract
A battery of audiological tests for retrocochlear disorders was performed on 79 cases with localized intracranial lesions which were confirmed surgically or neurologically. The type III trace of Békésy audiometry was found to originate from pathologies in the brain stem or in a more central region, and the type IV from abnormalities in the brain stem or in a more peripheral area. It was suggested that an unusually large amplitude peak in the Békésy tracing indicate a lesion in the temporal lobe. Large values of DLSI (Difference Limen of Short Increment) were found in patients with brain stem lesions. A normal hearing for pure tone with poor speech discrimination was specific to retrocochlear disorders. A good speech discrimination with poor filtered speech discrimination apparently indicated supra-tentorial lesions. The binaural separation test using dichotically presented digit sounds was performed. In the infra-tentorial group the discrimination on the ipsilateral side was poor. On the contrary, the discrimination score of contralateral ear declined in cases with supratentorial lesions.
