Auditory across-channel processing as assessed by monaural and between-ear temporal gap detection tasks

Gap detection is a measure of auditory temporal resolution. Hearing people exhibit acute sensitivity to silent gaps between leading and trailing markers when the two markers are identical or similar in frequency. However, sensitivity to such gaps declines when the two markers are of dissimilar frequencies. To examine the hypothesis that auditory gap detection performance declines during temporal comparisons of activity between different perceptual channels, we conducted monaural and between-ear temporal gap detection tasks. In the latter task, the leading and trailing sinusoidal markers delimiting the gap were presented to separate ears, which are regarded as independent channels, at least up to the superior olivary complex in the auditory brainstem. The between-ear gap detection thresholds were increased, even when the two markers were identical in frequency, and elevated gradually as the frequency difference between the two markers became greater than an octave. Furthermore, the patterns of the across-ear gap detection thresholds were roughly comparable with those of the monaural gap detection thresholds, except when the two markers were identical in frequency. These findings suggest that the different “across-channel” processes assessed by monaural and between-ear gap detection tasks share a common central mechanism for managing temporal information originating from different channels.