Roger Shepard is an American cognitive scientist and author of the ‘Universal Law Of Generalization’ (1987). The auditory illusion, Shepard tones, are named after him. He began his research on auditory illusions during his years at Bell Labs, where his colleague Max Mathews was experimenting with computerised music synthesis. Musicians and sound-effect designers use Shepard tones to create special effects.

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Shepard Tone – a sound consisting of a superposition of sine waves separated by octaves. When played with the bass pitch of the tone moving upward or downward, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that seems to continually ascend or descend in pitch, yet which ultimately gets no higher or lower.