Press play and close your eyes. Listen carefully to how the notes sound as if they are constantly climbing. And yet they never seem to change key or scale. What the f! is going on?
How It Works
What you hear is not a continuous track, but actually just a loop of a few tones repeating over and over. But how can a looped sound as though it is constantly and forever ascending or descending? Ask Roger N. Shepard, a Psychologist who in 1964 experimented with stripping pitch discrimination information (the frequencies that make pitches sound either high or low) from tones and then analyzing how the brain would process these tones.
Shepard created a “pitchless” cycle of Shehard Tones and looped them over and over again. Because the tones overlap each other, and because they are missing some pitch information, the UP Shepard Tones sound as if they continually ascending to new, higher scales. Each preceding Shepard Tone sounds as if it is lower than the next, while the proceeding tones sound higher than the last, even though we are actually just hearing a loop of the same tones over and over. It’s like walking down an up-escalator—constantly moving but somehow going nowhere. Super Mario 64 uses a truncated version of the Shepard’s Tone in the scene in which Mario is ascending the never-ending staircase.