Subjective duration of broadband noise impulses is investigated. At equal subjective duration, the physical durations of impulses may differe by up to 10%, the accruacy of duration measurements. For impulses shorter than 500 msec, subjective doubling of duration requires a ratio of physical durations larger than two, typically 2.6. This result is achieved by the method of constant stimuli. The subjective duration of impulses can be traced back to the corresponding temporal masking patterns. A model of subjective duration is proposed as follows: Whenever the sound pressure level of the temporal masking pattern reaches a critical value, marks are set. The temporal distance between these marks corresponds to the subjective duration of the sound. Applying the model, subjective doubling of impulse durations can be predicted from temporal masking patterns with an accuracy of typically 10%.