COMPARISON OF INTERAURAL TIME AND INTENSITY DIFFERENCE DISCRIMINATIONIN PATIENTS WITH TEMPORAL-LOBE LESIONS

We studied the sound lateralization in 15 patients with left (12 patie nts) or bilateral (3 patients) temporal lobe cerebrovascular lesions. The lesions included the auditory cortex. Interaural time difference ( ITD) and interaural intensity difference (IID) discriminations were se parately measured by using a self-recording apparatus. All 12 patients with left temporal lobe lesions could discriminate ITD, and their ITD thresholds were significantly higher than those in healthy volunteers . None of the 3 patients with bilateral temporal lobe lesions could di scriminate ITD. On the other hand, ail patients with either unilateral or bilateral temporal lobe lesions could discriminate IID and their I ID thresholds were significantly higher than those in healthy voluntee rs. The present findings indicate that the auditory cortex plays an im portant role in discriminating both cues, but that the role may not be essential for IID.