Make Noise posted a new video today demonstrating the Spiratone mode in their recent Telharmonic module, designed by Soundhack creator Tom Erbe. Make Noise has been supporting the Telharmonic with their in-depth video tutorials on their Youtube channel. But their most recent delves into a hidden mode based on a musical technique that gives the effect of an endlessly ascending or descending tone, referred to as a Shepard Scale. Using a number of detuned oscillators (traditionally detuned by an octave each) and changing the amplitudes of each oscillator depending on it’s relation to the center pitch, the Spiratone then shifts the pitch of all of the oscillators creating a rise or fall effect.
The Shepard Scale is named for Roger Shepard, a pioneer in cognitive science, who invented the Shepard Scale during his research into musical cognition. As an extension of his work on mental perception, Shepard studied the universal laws of musical perception and the relationship between tones and how the brain translates that information. His work has become the foundation of certain experimental music theory explorations as well, including the Tritone Paradox.
From the Rumelhart Prize page for Roger Shepard…
This is a sequence of sounds (now known as “Shepard tones”) which are each composed of multiple tones in octave relations, with fading amplitudes at each end of the frequency scale. Listening to the Shepard scale gives the illusion of an ever-ascending pitch. This illusion is analogous to Penrose’s illusion of ever-ascending steps, made famous by M.C. Escher’s wood engraving Ascending and Descending.
The Spiratone mode is perfect for creating some really wild sound effects. Using the Centroid control, you can detune the oscillators used to generate the Shepard Tones, which can be spread between the expected Octave pitch distance and nearly unison. The near unison tuning creates especially interesting atonal sounds which seem particularly useful for rises and falls.
Have you tried Spiratone mode? Tell us about your discoveries in the comments below!
Looking for a deeper understanding of your own synth? Check out our courses in the Lab!