Sympathetic Sentience

Simon Penny and Jamieson Schulte


Aesthetic and Theoretical Overview

Sympathetic Sentience Is an interactive sound installation which generates complex patterns of rhythmic sound through the phenomenon of 'emergent complexity'. The original goal was to attempt to realise a project which manifested true emergent complex behavior, using the simplest possible technology. Each of the 12 comparatively simple, identical electronic units alone is capable of only one chirp each minute. Rhythmic and melodic complexity develops through a chain of communication among the units. In the installation, each unit passes its rhythm to the next via infrared signal. Each unit then combines its own rhythm with the data stream it receives, and passes the resulting new rhythm along. Thus the rhythms and timbral variations slowly cycle around the group, increasing in complexity. The system is self-governing, after an initial build-up period, the system is never silent nor is it ever fully saturated.

The 12 units are mounted on the ceiling and walls of a darkened room. The experience of the visitor is of an active sound environment of 12 'channels' in which there is recognisable, but not predictable, patterning. The visitor can interrupt this chain of communication by moving through the space. This results in a suppression of communication activity and hence reduction of complexity. A long interruption results in complete silencing of the whole group. When the interloping is removed, slowly a new rhythm will build up. The build-up of a new rhythm cycle can take several minutes. The rhythm cycles are never constant but continually in development. To gain a sense of the full complexity of the piece, it is necessary to spend several minutes with the piece in an uninterrupted state.

Sympathetic Sentience: Technical Information

Sympathetic Sentience is an ongoing collaborative project which began in 1995. Several iterations of the work have been built. Sympathetic Sentience One was built entirely in hardware logic (TTL ICs). The basic technical premise is extremely simple: each unit is receiving, processing and forwarding a continuous stream of data. Each unit 'edits' that stream 'on the fly', adding or omitting an occasional bit. This editing is done in such a way that the 'density' of the sound is 'self-governing'. The critical part of each unit is an exclusive OR gate. On each unit, the signal is received by an IR receiver, demodulated and sent to a shift-register (delay). Emerging from the delay it meets a feed from the on-board oscillator at the exclusive OR gate. The signal emerging from the gate goes to both the IR emitter and the audio amplification circuit. The units communicate in modulated infrared signals using hardware similar to that used in TV remote controls.While in Sympathetic Sentience One, only the rhythmic patterns were subject to change through the emergent complex behavior, in Sympathetic Sentience Two, other sound characteristics such as pitch and envelope are also subject to gradual change through the emergent complex process. To achieve this, Sympathetic Sentience Two uses small microprocessors (PICs) to replace the hardware logic, this allows new versions of the code to be downloaded.

Jamieson Schulte is an electrical engineer and sound artist. In the mid 90's he was research staff in the CMU Computer Science Department, focusing on the use of machine learning in building control at the 'Intelligent Workplace' laboratory. His sound experiments involve dynamic electronic synthesis and composition systems that interact with human players. He has worked collaboratively with Simon Penny since 1995, developing code and hardware for Petit Mal, Sympathetic Sentience and Fugitive.

In Sympathetic Sentience Three we continue to explore the possibilities opened by the use of microprocessors. Various fixed characteristics are open to variation dependent on the environment. Such variations include the delay length and other internal timing issues, ëmixing modeí (previously restricted to exclusive OR), long term drift in sound quality and a more complex range of behaviors resulting from human interaction. In addition, parts of the electronic and mechanical hardware are upgraded.

Beyond Sympathetic Sentience Three, there are plans for permanent outdoor and indoor versions.