The detection threshold of a single gap in white noise was measured as a function of the gap duration. The results can be described with an auditory integration time of about 25 ms. This value is much larger than the 3--4 ms usually found in experiments on auditory temporal integration. The discrepancy shows that a system theoretical description of the detection of arbitrary amplitude changes in noise in terms of a modulation transfer function, fails to explain the detection of a single gap.