Shepard Tone

An auditory barber’s pole: layered octaves fading in and out to climb forever without getting higher.

Core Principles & Analysis

• Roger Shepard described the illusion in 1964 using octave-spaced components under a fixed loudness envelope.
• The continuous version, the Shepard–Risset glissando, seems to rise eternally.
• Film scores use it to manufacture unresolved tension — most famously throughout Dunkirk.

Specifications & Metrics

• FREQUENCY: Illusory endless glissando