Shepard Tones: Dunkirk

The Shepard tone, named after Dr.Roger Shepard, a cognitive scientist that worked for Harvard university and Bell Laboratories, is an audio illusion that exploits the human brains inability to follow multiple pitch and dynamic changes at the same time. This illusion consists of three rising scales, each an octave apart, with the highest falling in volume, the lowest rising and the middle staying at the same. As stated before, when these scales are rising and automating in volume we are unable to track the progress of each and we perceive this as a constant rising tone.

This is effective in a musical score because it is an endless supply of tension. When we hear scales rising chromatically, the intervals between the notes are not harmonious, if the instrument has release and this combined with the Shepard tone help to force viewers to the edge of their seats.

 

Here is an example of Shepard tones at work in the film Dunkirk, composed by Hans Zimmer.

 

 

I used a synthesiser, with a noise oscillator mixed in, to create this effect within my Philips Carousel project. I introduced the noise oscillator to introduce more paranormal connotations.  I played a chromatic scale started at the route note of the project (E) spanning over an octave, duplicated this over three track.  I found that if i applied the Shepard tone module with the velocity it left me free to mix the overall dynamics of the tone. Alongside volume automation, the Shepard tone proved to be fairly effective.