Deutsch's scale illusion is an auditory illusion in which two series of unconnected notes appear to combine into a single recognisable melody, when played simultaneously into the left and right ears of a listener. The illusion is produced by simultaneous ascending and descending

major scale The major scale (or Ionian mode) is one of the most commonly used musical scales, especially in Western music. It is one of the diatonic scales. Like many musical scales, it is made up of seven notes: the eighth duplicates the first at double ...

s beginning in separate stereo channels with each successive

note Note, notes, or NOTE may refer to: Music and entertainment * Musical note, a pitched sound (or a symbol for a sound) in music * ''Notes'' (album), a 1987 album by Paul Bley and Paul Motian * ''Notes'', a common (yet unofficial) shortened version ...

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. The tones are equal-amplitude sine waves, and the sequence is played repeatedly without pause at a rate of four tones per second. When listening to the illusion over headphones, most right-handers hear a melody corresponding to the higher tones as on the right and a melody corresponding to the lower tones as on the left. When the earphone positions are reversed, the higher tones continue to appear to be coming from the right and the lower tones from the left. Other people experience different illusions, such as the higher tones on the left and the lower tones on the right, or a pattern in which the sounds appear to be localized in different and changing ways. Right-handers and left-handers differ statistically in how the scale illusion is perceived. The effect was discovered by

Diana Deutsch Diana Deutsch (born 15 February 1938) is a British-American psychologist from London, England. She's a Professor of Psychology at the University of California, San Diego, and is a prominent researcher on the psychology of music. Deutsch is p ...

in 1973. In a clinical study, patients with

hemispatial neglect Hemispatial neglect is a neuropsychological condition in which, after damage to one hemisphere of the brain (e.g. after a stroke), a deficit in attention and awareness towards the side of space opposite brain damage (contralesional space) is observ ...

were shown to experience the scale illusion. Further, in an MEG study on normal listeners the scale illusion was found to be neurally represented at or near the auditory cortex.

Sources

External links

Diana Deutsch's scale illusion page at UCSD

Stereo Sound Example of Deutsch's scale illusion
{{DEFAULTSORT:Deutsch's Scale Illusion Auditory illusions Music psychology

Further reading

Sources

External links