82 , 2016-07-29 , 金沢大学つるま保健学会 = Tsuruma Health Science Society, Kanazawa University
We conducted sound lateralization tests that involved determining the location of a sound image, using inter-aural time difference （ITD） as an indicator, for four patients exhibiting right unilateral spatial neglect （USN） due to damage in the left cerebral hemisphere. In the sound lateralization test, the right/left ratio of the ITD discrimination threshold was determined, and the percentage increase was calculated in the right ITD discrimination threshold relative to that on the left. The right/left ratio of ITD discrimination threshold ranged from 1.18 to 2.76. This study revealed that threshold level was significantly elevated on the right side for right USN patients. Specifically, it was difficult for right USN patients to perceive a sound image shift from the center to the right side. In the sound lateralization test, ITD discrimination ability was measured using a selfrecording apparatus. Subjects were requested to press the button in the switch box as soon as possible when they perceived whether the location of the sound image was biased toward the right or the left side from the center. This analysis indicated that right USN patients have reduced recognition ability for right auditory stimulation; right-side sound images may be shifted leftward in their sound location function. This phenomenon was thought to be related to allocentric neglect.