音像定位能力に対する前庭刺激の影響

Abstract

Using dichotic sound, the effect of vestibular stimulation on the orientation of sound lateralization was investigated in 13 subjects. The interaural time difference (ITD) discrimination test was performed in a dark room while caloric nystagmus was induced by iced water irrigated into the external auditory canal. The amplitudes for the ITD discrimination tests after caloric stimulation (experimental group) were significantly greater than those before caloric stimulation (control group). During caloric stimulation, all subjects reported that their perceptual body axes shifted toward the slow phase side of nystagmus, and the median line of amplitude for the ITD discrimination test shifted to the slow phase side of the nystagmus. In contrast, when subjects were gazing a visual target fixed straight ahead of subjects, there was no significant difference in the amplitudes or the median line shift of amplitude was observed between the control and experimental groups. The current study suggests that sound lateralization sensitivity during ITD discrimination may be altered by vestibular stimulation.