Chirashi: A musical swarm instrument with live control.
by Daniel Waghorn. (JavaScript required to view email address)

This page contains demonstration videos of Chirashi, the musical swarm instrument.

Test cases:

Test 1: Consonance and dissonance
Test 2: Industrial percussion
Test 3: Counterpoint

Compositions:

Equinox
The circling sun

Test 1: Consonance and dissonance

Swarm behaviours that encourage tight (but not overlapping) dwelling over goal locations tend to cause clusters of notes with small pitch class intervals, which creates structures that suggest dissonance. Adding strong repulsion from other agents and urging agents to move quickly toward distant goals has the opposite effect, creating large intervals and complex, rapidly changing melodies. The result is not strictly harmonic, but suggests a more stable tonal foundation, giving the impression of relative consonance.

Test 2: Industrial percussion

When the stylistic requirements of a musical piece are strict, constraints on swarm behaviour and interpretation can ensure that the complex and organic behaviour of the swarm can still produce useful output. MIDI-compatible drum machines often map different drums in a kit to notes in pitch class space, making drum sounds explorable by the swarm. Strong attraction to a single value in timing space causes the swarm to produce stable, rhythmic pulsing; while encouragement to move in pitch space allows the swarm to trigger different drum sounds, creating dynamic but robotic sounding industrial beats.

Test 3: Counterpoint

This piece exploits flocking behaviours to keep two agents relatively close to one another, each following the other's movements while dancing about wildly due to strong, random forces. A single goal is used to encourage consistent timing, while conflicting forces of random motion, neighbour avoidance and directional alignment cause the two agents to play melodies that develop randomly, but frequently synchronising for brief moments. The result is a dual melody line reminiscent of counterpoint, both following and changing directions whimsically.

Equinox

A live synthesiser composition using multi-swarms to produce lead and accompaniment sections, combining aesthetics of early 90s house music and ambient electronica. Two distinct groups of agents are guided by goals to occupy different areas of pitch space and timing parameters, separating the sounds into foreground and background. Slowly changing dynamics come from changes in timing goals, when agents go from a flurry of activity to a softer lull, playing with musical tension while developing the musical soundscape.

The circling sun

A multi-swarm composition that maps each swarm to a separate MIDI instrument. A large population in rapid motion plays notes in a pentatonic scale, evoking the sounds of traditional Chinese guzheng music, played with the instruments of the contemporary orchestra. A large repulsor is placed in the centre of pitch and time spaces, while one swarm is guided to move to the centre of the repulsor itself. Unable to reach the centre due to the repulsor's influence, the agents are instead deflected and begin to move in orbits around the goal, creating oscillations in multiple parameter spaces. The alignment behaviour in both swarms causes the second swarm, situated far from the orbiting swarm, to 'catch' the orbital motion, making it move in similar patterns despite its distance from the first swarm.

CHIRASHI