A Shepard tone is an aural illusion where the pitch of the sounds appears to be ever increasing.

This can create a sense of tension since the tone never seems to resolve.

The Shepard tone effect has been used in many films over the years. I was made aware of the effect years ago in school but was reintroduced to it a few years ago when Randy Tom used it in the movie “Flight” to add tension to a particularly long crashing descent.

And more recently, it was used in Dunkirk by the composer Hans Zimmer. These inspired me to do some experimenting with creating some Shepard tones for myself.

Many in this collection are synthesized and intended to be used as a layer within an additional bed of sound. A few are quirky attempts at discovering what variety of sounds could be used and still keep the illusion intact.

The bubbles recording is a good example of that. Some of these were sourced from acoustic recordings, like the fans and motors.