xCoAx 2020 8th Conference on Computation, Communication, Aesthetics & X 8–10 July, Graz online

Polyharpye Reclaimed

Keywords: Complexity, Networks of Influence, Xstruments, Improvisation, Spatialisation.

The initial context of this piece is On Air, a Tomas Saraceno solo show at Palais de Tokyo [1]. The concept claimed that all the artworks form a network of information; Dominik Hildebrand (then technical wizard at Studio Saraceno) proposed that, sound being the medium that permeates everything, it should be sound that flows between the nodes. He invited Hannes Hoelzl and me to help realise this concept. The capstone of the show was Algo-r(h)i(y)thms, a large sculptural installation of ropes forming geometric shapes, suspended on ropes terminating on walls, ceiling and floor, filling the space with a complex network of rope objects. [2]

The Sound World underlying Polyharpye was originally created as the sonic complement for this piece: 64 suspension rope end points were fitted with custom piezo pickups, providing polyphonic vibration signals when ropes were plucked, rubbed or otherwise excited. I built dynamic possibility spaces for it: multiple scales, tunings, pitch/location mappings; multiple resonating processes to be informed by rope-touch sounds; scenes with multiple sounding layers, mapped to space/pitch subsets; and crossfading between scenes.

When Saraceno decided to exhibit a simple first demo instead of my creation, I realised that while play the sound world from the installation is enjoyable, depending on this elaborate and expensive setup makes it inaccessible. Thus, I decided to make it accessible at much lower cost and effort, simultaneously gaining in transportability and artistic control.

The MTP interface leverages multitouch trackpads, which track up to 11 fingers in position and touch-size, with good resolution and low latency. It maps intuitively onto spatial layouts, activating specific locations, their associated pitch and mapped sound processes with synthetic sound.

The Polyharpye interface leverages designs from Utopologies [3], a project by the Society for Nontrivial Pursuits, where Christian Schmidts algorithmically designed bodies for a network of simulated creatures. The bodies consist of laser-cut plexiglass plates with small holes for hooks to attach stabilizing strings, and larger holes for access. Noticing the physical analogy to large-scale networks of ropes, we designed a family of self-similar dodecahedral bodies with suspended strings and custom piezo pickups, remapping the sounds dynamically to the sound layer inputs.

The Polyharpye’s design for nontrivial behavior qualifies it as an Xstrument, a term Hannes Hoelzl and me coined for performance systems where agency is designed to be shared between human and machinic/algorithmic partners, the X meaning exploratory, experimental, unknown. We continue here a tradition ranging from Louis and Bebe Barron’s “semi-autonomous creatures” (Laudadio 2007) via Peter Blasser’s “analog brains” (Blasser N.D.) to Laetitia Sonami’s transition from the Lady’s Glove to the Spring Spyre, forgoing classical HMI notions of control. Xstruments often deploy sound processes with rich “inner life” by feedback topologies (as with the Rungler, Hordijk 2009), and what we call MetaControl, where notions of full control are given up in favor of intuitively learnable modes of influence (de Campo 2014, Hildebrand et al. 2017)

The performance at xCoAx / MuMuth

The performance will be an improvised exploration of the sound world for ca. 10-12 minutes. The option of 3D-positioning 29 speakers at MuMuth is ideally suited for creating spatial situations for the superposed layers that let the audience appreciate the complexity of the experience more deeply.


Many of my software libraries are being developed with the SuperCollider community; and many of my musical concepts are co-developed with my artistic partner Hannes Hoelzl, and refined with our students and alumni. Special thanks to our alumnus and friend Dominik Hildebrand for inviting us to collaborate on the show at Palais de Tokyo, where Polyharpye began.


  1. studiotomassaraceno.org/on-air
  2. studiotomassaraceno.org/algo-rhiythms
  3. earweego.net


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