An illusion occurs when the auditory component of one sound is paired with the visual component of another sound, leading to the perception of a third sound.

How can illusion be created?

Illusions are special perceptual experiences in which information arising from “real” external stimuli leads to an incorrect perception, or false impression, of the object or event from which the stimulation comes. ... Another group of illusions results from misinterpretations one makes of seemingly adequate sensory cues.

When did illusions become a thing?

The history of optical illusions can be traced back to the 5th century B.C. when Epicharmus first presented the explanation of this phenomenon. Epicharmus believed that even if our mind knows and understands everything clearly, the sensory organs deceive us and present an optical illusion.