In audio, the Shepard tone describes a constant sound which has an illusion of a forever rising or falling pitch.
Named after cognitive scientist Roger Shepard who demonstrated forever ascending or descending visual and auditory illusions. The visual illusion is still used today, typically by barber shops. I’m sure you recognize the corkscrew effect in the image below.
Since the 1960’s the audio illusion has been used in multiple ways, adopting the concept in rhythm (Risset Rhythm) to more common pitch risers. The illusion can create great suspense as the listener is always waiting for it to reach its peak, but it never does.
The Shepard tone is used today in different genres of music, film soundtracks and game design. The following examples demonstrate the Shepard Tone played on a variety of instruments including an Orchestra in the soundtrack to Dunkirk, Guitar FX used by Franz Ferdinand, Slide Guitar from Godspeed you Black Emperor and Sound Effects such as an forever accelerating Batpod. I have also included some tutorial videos made by some of my favorite youtube educators, Will from EDM Tips and Oscar from Underdog.
Shepard Tone examples in music and sound design
The Shepard Tone is an extremely powerful illusion which has been successfully adopted in film soundtracks and film sound design where suspense is created and sustained for long periods of time. It can create hyper realism, and it works great in a surreal or mysterious environment.
Some great examples of an ascending Shepard Tone being used in sound design;
Super Mario 64 - Endless Stairs
The soundtrack to the endless stairs scene on Super Mario 64 wisely uses the endless Shepard tone. The music is played in a musical scale which is simply repeated and creates the illusion the notes are constantly increasing in pitch.
Hans Zimmers use of Shepard Tones
Han Zimmer makes great use of the Shepard Tone in many of his film scores, creating intense build ups and feelings of panic or intense anxiety. In the Film Dun Kirk, the Shepard tone is used as part of the musical arrangement. The Shepard Tone combined with the sound of ticking makes it very clear on the emotions Hans Zimmer was aiming to induce.
Batman Dark Night uses the Shepard Tone in multiple places, less musically than Dun Kirk, but used more as a sound design piece. Hans Zimmer uses the Shepard Tone before the Joker is introduced, giving the viewer a feeling of anxiety and the belief that something is going to happen.
Perhaps the more talked about scene which makes use of the Shepard Tone, is the Batpod scene. The Shepard Tone is used to give the impression the motor bike is going forever faster.
I’m sure, now you can recognize the effect, you will notice this in many other film scores due to its power to create panic, anxiety or never ending suspense. Of course this effect can also be powerful in music especially where the composer, songwriter or producer wants to create an out of world or hyper real experience.
Examples of Shepard Tone in music
Franz Ferdinand -Always Ascending
You can hear the Shepard Tone from the very start of the song with an ascending rising effect which continues to rise throughout the intro. The track then uses the effect throughout the track to match the appropriately themed song.
The Beatles – I Am The Walrus
Used at the very end of the song but matches the songs rising chord progression and out of this world themed lyrics.
Godspeed you Black Emperor – The Dead Flag Blues
A band know for dark and epic sound track fitting music, making use of a variety of instruments, effects and techniques. All the previous examples has used ascending Shepard Tone but the dead flag blues uses a slide guitar to create a descending Shepard Tone . The whole track uses descending progressions but at 7m 40 seconds the Shepard Tone is used to back the sound of a train, in keeping with the feel of the whole track, it makes you feel like your falling through the undergrowth or gaps in the pavement.
Shepard Tone in rhythm
This is called a Risset Rhythm named after its creator Jean-Claude Risset where the rhythm constantly feels like it is speeding up. I have included the following example which combines multiple versions of the Shepard Tone , visually, rhythmically and pitch. I wouldn't recommend this video to the faint hearted.
How to create the Shepard Tone
The main principle on creating a Shepard Tone is fading out 1 ascending, or descending, tone and fading in another, then repeating the process for as long as you wish. There are multiple ways to achieve this, you could program this in the synth itself using 2 oscillators, or use MIDI to trigger the scale from 2 synthesisers and automate to fade in and out of the 2 instruments.
I find using MIDI is the easier way due to its visual advantages, can be used with monophonic synthesisers which gives you greater control. You can also use this method with audio files and samples used in a sampler.
Will from EDM Tips demonstrates using the pitch bend with 3 different oscillators covering 3 different octaves to fade the ascending Shepard Tone.
Oscar from Underdog covers the Shepard Tone being used as riser as well giving a very interesting rhythmical example.
I hope you enjoyed seeing what a powerful illusion the Shepard Tone can be,