Deutsch's scale illusion
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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
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
left-handers
differ statistically in how the scale illusion is perceived.
The effect was discovered by Diana Deutsch in 1973. In a clinical study, patients with hemispatial neglect 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.
Further reading
- Deutsch, D. (1974). "An illusion with musical scales". Journal of the Acoustical Society of America. 56 (S1): s25. ]
- Deutsch, D. (1975). "Two-channel listening to musical scales". Journal of the Acoustical Society of America. 57 (5): 1156–1160.
- Deutsch, D. (1975). "Musical Illusions". Scientific American. 233 (4): 92–104. PMID 1162325.
- Deutsch, D. (1979). "Binaural integration of melodic patterns". Perception & Psychophysics. 25 (5): 399–405. PMID 461100. PDF Document
- Deutsch, D. (1983). "Auditory illusions, handedness, and the spatial environment". Journal of the Audio Engineering Society. 31: 607–618.
- Deutsch, D. (1985). "Dichotic Listening to Melodic Patterns and Its Relationship to Hemispheric Specialization of Function". Music Perception. 3 (2): 127–154. S2CID 33980647. PDF Document
- Deutsch, D. (1987). "Illusions for Stereo Headphones". Audio Magazine: 36–48. PDF Document
- Radvansky GA, Hartmann WM, Rakerd B (1992). "Structural alterations of an ambiguous musical figure: the scale illusion revisited". Perception & Psychophysics. 52 (3): 256–62. PMID 1408637.
- Deutsch, D. (2013). Grouping mechanisms in music In D. Deutsch (Ed.) (3rd ed.). pp. 183–248.
- Kuriki, S.; Yokosawa, K. & Takahashi, M. (2013). "Neural Representation of Scale Illusion: Magnetoencephalographic Study on the Auditory Illusion Induced by Distinctive Tone Sequences in the Two Ears". PLOS ONE. 8 (9): e75990. PMID 24086676. PDF Document
- Deouell, L. Y.; Deutsch, D.; Scabini, D.; Soroker, N. & Knight, R. T. (2008). "No disillusions in Auditory Extinction: Perceiving a Melody Comprised of Unperceived Notes". Frontiers in Human Neuroscience. 1: 15. PMID 18958228. PDF Document