Illusory continuity of tones

The illusory continuity of tones is the auditory illusion caused when a tone is interrupted for a short time, during which a narrow band of noise is played. The noise has to be of a sufficiently high level to effectively mask the gap, unless it is a gap transfer illusion. Whether the tone is of constant, rising or decreasing pitch, the ear perceives the tone as continuous if the discontinuity is masked by noise. Because the human ear is very sensitive to sudden changes, however, it is necessary for the success of the illusion that the amplitude of the tone in the region of the discontinuity not decrease or increase too abruptly. While the inner mechanisms of this illusion are not well understood, there is evidence that supports activation of primarily the auditory cortex is present.