Previous studies from our laboratory have shown that auditory cortical evoked potential thresholds (N1-P2) decrease with increasing stimulus duration. Similar to behavioral studies of auditory temporal integration, N1-P2 threshold improvement was greater for 1000-Hz than 4000-Hz stimuli. It is unclear whether spectral splatter at short durations contributed to the threshold differences across frequency. The present study investigated spectro-temporal influence on N1-P2 thresholds by manipulating the stimulus rise–fall time, total duration, and stimulus type. Thresholds were estimated in three temporal conditions to compare stimuli with equal rise–fall (2 ms) but different total durations (8, 36 ms), and stimuli with different rise–fall (2, 16 ms) but equal total durations (36 ms). Broadband noise bursts and 1000-Hz tones were used to test each temporal condition. Preliminary results show that thresholds for both noise and tonal stimuli decrease with increasing total duration. No significant differences in threshold were observed as a function of rise–fall time nor were significant differences observed as a function of the stimulus type. The results suggest that N1-P2 thresholds are determined primarily by changes in total duration and that thresholds for short durations at 1000 Hz are not adversely affected by spectral splatter. [Work supported by NSF.]