Illusory discontinuity is an auditory illusion in which a continuous ongoing sound becomes inaudible during a brief, non-masking noise. The illusion is perceived only by some listeners, but not by others, reflecting individual variation in hearing abilities. It has been estimated that among young adults 24% are susceptible to illusory discontinuity. The most susceptible listeners describe their sensations in terms of the sound actually containing a physical gap. The illusory discontinuity is strongest when the interrupting sound is short (50ms). Longer sounds elicit weaker illusory discontinuity; this effect may be related to better auditory segregation.