Risto Holopainen's PhD project in music technology
at the Department of Musicology, University of Oslo.
Project description
What are autonomous instruments?
Occasionally one hears of semi-autonomous instruments. These are typically digital instruments that use machine listening techniques to interact with a performer. Remove the realtime interaction and the performer, and an autonomous instrument is what remains.
A more technical and precise term for the kind of instrument this project deals with would be feature extractor-feedback systems, or feature-feedback systems for short. They are
- feedback systems containing feature extractors in the loop
- a combination of sound synthesis with algorithmic composition
- but not necessarily interactive in realtime
Feature-feedback systems can be conceptually broken down into three units: a signal generator, a feature extractor, and a mapping from the analysed features to the control parameters of the signal generator. Hence there is a constant feedback from the sound generated at any moment to the settings that influence how the sound is generated.
Schematic of autonomous instruments. 'G' represents any signal generator, 'A' is a feature extractor, and 'M' stands for mapping.
In adaptive audio effects (A-DAFx), effect parameters are controlled by extracted features from an input sound. Feature-feedback systems take their own output as a point of departure; hence they may be thought of as self-organising systems.
The feature-feedback systems are studied from the point of view of chaos, nonlinear dynamical systems and complex systems theory. The project as a whole aims towards a better understanding of these synthesis models in terms of relations between parameter spaces and perceptual dimensions.
Remark on terminology
The word autonomous should be understood roughly as it's used in the context of differential equations. Essentially, it means that the user has no real-time control over the instrument.
PhD Thesis
Self-organised Sound with Autonomous Instruments: Aesthetics and experiments.There are direct links to sound examples in this document, which can also be found here.
Selected Papers
Feature Extraction for Self-Adaptive Synthesis
Published in SonicIdeas/IdeasSonicas Vol. 1, No 2, pp. 21-28, 2009.
Nonlinear Filters
Poster published in the Proceedings of the ICMC 2007, Vol 1, pp. 283-286. Copenhagen, Denmark.
A review of some common nonlinear filters.
Building Autonomous Instruments
Full original project description written in 2008 (with obsolete terminology!).
Logistic map with a first order filter
(Preprint version.) Submitted to International Journal of Bifurcation and Chaos in 2010,
published in Volume 21 Number 6 June 2011.
Self-Organised Sounds with a Tremolo Oscillator
This paper was presented as a poster at DAFx-10 in Graz, September 2010.
Other presentations
Lecture at
NMH September 16, 2010
Brief presentation (in Swedish)
Project description at the Department of Musicology
Other project description at HF
contact: risto.holopainen (at] imv.uio.no
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