What is Shepard Tone?

Описание: A Shepard tone, named after Roger Shepard, is 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.

Never-ending and Infinite, while everything else always comes to an end the Shepard Tone may be the one thing that truly doesn’t stop. This audio illusion is more than just a novelty, however, and filmmakers like Christopher Nolan have embraced it in their work. From sound effects to the musical score, nothing ramps up tension quite like the Shepard Tone.

Aside from Nolan, the concept had primarily been used in popular music by groups like The Police, Pink Floyd, or in electronic music to build up before a kick. For example, Franz Ferdinand with his track using the Shepard Scale, appropriately titled "Always Ascending."

You can basically think of Shepard tones as the audio equivalent of a barber pole. In that illusion, our brains interpret the diagonal stripes on the rotating pole as moving vertically upward(and even ‘disappearing’ as they reach the top, even though they’re really just moving around the pole. In a discrete Shepard scale, this same illusion is achieved by fading each scale in and out to create seamless transitions that loop perfectly, without giving you any sense of where a scale starts or ends.