Interaural Intensity Difference for Intracranial Lateralization

Abstract

The interaural intensity difference (IID) for intracranial lateralization of white-noise bursts was investigated in 17 normal subjects, in 17 subjects with high-frequency sensorineural hearing losses, and in 17 subjects with predominantly unilateral cerebral lesions. Broad-band- and low-pass filtered-noise bursts with durations of 76 msec and 506 msec and a fast rise time of 10 msec were used for the dichotic signals. These were presented relative to the hearing sensitivity in each ear. There were no statistically significant differences between normal and sensorineural subjects except for the filtered noise condition, which resulted in a slightly but significantly greater IID for subjects with hearing losses. In subjects with cerebral lesions, the IID for the ear contralateral to the lesion was much smaller than the IID for normal or sensorineural ears, while the IID for lateralization to the ear ipsilateral to the lesion was slightly larger than the normal IID. It was found that the model for neural interaction in stimulus lateralization that von Békésy developed on the surface of the skin could be applied to the auditory phenomenon of sound lateralization.