The effect of optokinetic stimulation on orientation of sound lateralization

CONCLUSIONS: The current study demonstrates that sound lateralization sensitivity during interaural time difference (ITD) discrimination may be altered by optokinetic (OK) stimulation, and that sound lateralization sensitivity of ITD discrimination may be more susceptible to OK stimulation than that of interaural intensity difference (IID) discrimination. These data suggest that nystagmus or the sensation of self-rotation induced by OK stimulation influences auditory afferent information such as sound lateralization. OBJECTIVE: Using dichotic sound, the effect of optokinetic stimulation on the orientation of sound lateralization was investigated in humans. MATERIALS AND METHODS: Subjects were studied by testing ITD and IID discrimination during OK stimulation. RESULTS: At 90 degrees/s of the light stripes angular velocity the amplitudes for the ITD discrimination tests during OK stimulation were significantly greater than those either before the beginning of OK stimulation or at 30 degrees/s (p<0.05). No significant difference in the amplitude for the IID discrimination test was observed between the results obtained before and during OK stimulation. During OK stimulation, all subjects felt that their perceptual body axes shifted toward the quick phase of OK nystagmus. In 8 of 12 subjects, the median line of amplitude for the ITD discrimination test shifted to the quick phase side of the OK nystagmus.