Discovered by Diana Deutsch, Deutsch's scale illusion is an auditory illusion produced by simultaneous ascending and descending major scales beginning in separate stereo channels with each successive note being switched to the opposite channel. With the left channel: C'-D-A-F--A-D-C'; and the right: C-B-E-G-E-B-C; the ear hears both: C'-B-A-G--A-B-C'; and: C-D-E-F--E-D-C. Two complex patterns are turned into two much simpler patterns. Diana Deutsch is a perceptual and cognitive psychologist, born in London, England. ... An auditory illusion is an illusion of hearing (sense), the sound equivalent of an optical illusion: the listener hears either sounds which are not present in the stimulus, or impossible sounds. ... Stereo or stereophony generally refers to dual-channel sound recording and sound reproduction – sound that contains data for more than one speaker simultaneously. ...