Jean-Claude Risset described the auditory illusion of an “eternal accelerando”, where, similar to Shepard tones for pitch, a rhythm can be structured and played back in a way that creates the perception of constant acceleration.
In his 2011 paper “Scheduling and composing with Risset eternal accelerando rhythms”, Dan Stowell provided a solution for implementing eternal accelerandos on (rhythmic) audio samples by employing variable play back rates and amplitudes distributed to a number of sample play back streams that run synchronized.
Pure Data implementation
Risset Sampler is a Pure Data implementation of an eternal accelerando I programmed following Stowell’s paper.
The sampler has 5 streams set up to play back any given sample in a loop to generate the eternal accelerando effect. The individual play back rates and depending amplitude envelopes for each stream are calculated based on Stowell’s formulas (2) and (3).
In addition to the stand alone risset_sampler.pd abstraction, i’ve also provided a modular version in the repo that can be embedded into larger compositions.
Risset Remixes
With the modular version of the Risset Sampler (jaycee.pd), I’ve done experiments on composition level which resulted in the Risset Remixes.
MARTSM<>N – Risset Remixes [datamarts/2KOMMA2]: Bandcamp, Nina
For these, I’ve been using stems from my tracks Axe Why Dread, Ting and Double Dub. In each composition, sample loops separated from these stems are being played back using the jaycee.pd abstraction.
Events within the compositions are triggered by the completion of sub stream cycles in each sampler, creating a generative, closed circuit system. On the remix of Ting, manual triggers were also applied during recording.