Past studies have shown that within-channel auditory gap detection tasks are processed by the auditory periphery whereas across-channel auditory gap detection tasks require the intervention of central processes. Previously, we found a left-hemispheric bias for a within-channel task and a right hemispheric bias for an across-channel task (Estes & Jerger, 2002 SFN abstract). This result implies that spatial perception rather than temporal resolution dominates the across-channel task. Two studies are presented here; the purpose of the first study was to investigate differences in across-channel gap detection in three different age groups. The purpose of the second study was to investigate whether boys with an auditory processing disorder (APD) exhibited an electrophysiological response different in latency or amplitude from boys with no auditory processing disorder on within and across-channel temporal gap detection tasks. In the age-related study there were 30 right-handed participants (11 boys, 10 young men...