The scale that rises forever
Turn up the sound and start the scale. Listen: is it really rising?
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What most people do: Almost everyone hears a continuous rise.
What just happened (read it after the experiment)
Each note is a stack of the same note over several octaves. The highest ones fade out gently while lower ones fade in: your ear follows the climb without noticing the handover.
Roger Shepard created this illusion in 1964. Hans Zimmer and Christopher Nolan used it in Dunkirk (2017), for tension that never lets up.
It is the sound equivalent of Penrose’s never-ending staircase.
More experiments
Sources
- Roger Shepard, “Circularity in judgments of relative pitch,” Journal of the Acoustical Society of America, 1964.