Absolute and differential thresholds for a single temporal discontinuity, or “gap,” were obtained for auditory pulse trains as a function of: (1) the interpulse interval surrounding the gap region, and, (2) the magnitude of the reference gap. Under conditions implicating a spectral analysis, e.g., a large number of pulses at high pulse frequencies, the differential asynchrony threshold is extremely sensitive to the ratio of the reference gap to its surround. Under such conditions, the differential asynchrony threshold increases sharply as the gap/surround ratio changes by a factor of 2, but is relatively independent of still further changes in the gap/surround ratio. Under conditions implicating a temporal analysis, e.g., at low pulse frequencies, or an incomplete spectral analysis, e.g., a small number of pulses at high pulse frequencies, the differential asynchrony threshold is relatively insensitive to the gap/surround ratio.