The detection of a 5‐msec tonal signal presented at various delays after the onset of a 500‐msec tonal masker was investigated in several transient‐masking experiments. Changes in the amount of masking were measured as a function of the delay between onset of the signal and the onset of the longer‐duration masker. In agreement with previous investigations of transient masking there was a large decrease in masked threshold, 26 dB in some conditions, with an increase in signal delay. A “transient overshoot” at masker termination was also noted. These data are consistent with a short‐time energy‐sensing model of detection. In a second transient‐masking study, the masking produced by a gated sinusoid in the presence of a continuous tonal pedestal was investigated. The pedestal results indicate that a simple, linear, time‐invariant, energy‐detection scheme cannot account for the results of two‐tone masking experiments.