A Shepard tone creates an endlessly ascending pitch while staying within one octave
Evidence
“Shepard tone.” This illusion produces the sensation of an endless scale that ascends in semitone steps. After 12 semitone steps when the pitch has risen by one octave, the spectrum is identical to the starting spectrum, so the scale ascends but never climbs acoustically more than one octave. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1641
Categorization
Category: Factual Claims
- XREF: Ties to the reader’s broader interest in auditory illusions and sonic deception; relates to the chapter’s theme of deceiving the ear.
- CANDY: The endlessly ascending scale that never actually climbs is a fun, shareable fact.
Related
- Shepard tones create endlessly rising pitch through shifting autocorrelation peaks (similarity 0.85)
- A rising pitch can perceptually loop back to its start. (similarity 0.84)
- Shepard tones are not perceptually identical across the octave. (similarity 0.84)
- Shepard tones use only power-of-two partials plus amplitude shaping to create the illusion. (similarity 0.81)
- A sound can rise in pitch forever without ever rising in frequency (similarity 0.81)
- Endlessly accelerating beat rhythms are Shepard tones shifted down in frequency. (similarity 0.80)