The Shepard demonstration revisited, again
Edward McN. Burns · The Journal of the Acoustical Society of America · 1979
The Shepard illusion (“auditory stairway to heaven”), in which the presentation of a cyclically repetitive sequence of complex tones composed of partials separated by octave intervals gives the illusion of continually rising pitch [Shepard, J. Acoust. Soc. Am. 36, 2346–2353 (1964)] is often cited as evidence for octave equivalence in relative pitch judgments. Evidence will be presented which demonstrates that this illusion can be produced using inharmonic complex tones (e.g., tones whose partials are separated by stretched or compressed “octaves”) and, thus, octave separation of partials is not a necessary condition for producing the illusion. [Work supported, in part, by NINCDS.]