Audio Spray Gun 0.8 – the Generation of Large Sound-Groups and Their Use in Three-Dimensional Spatialisation Richard Garrett Bangor University, Wales, UK mupe04@bangor.ac.uk ABSTRACT Audio Spray Gun is a computer program that simultaneous- ly generates and spatialises large groups of sound events derived from a single sound sample. This is achieved by constraining random events to a transformable locus within a multi-dimensional parameter space, using a method anal- ogous to the spray gun function found in computer graphics programs. Recent developments in this software include three-dimensional spatialisation and the use of metadata for the storage of sound-groups. This paper describes the pro- gram and discusses the implications of these developments for editing and spatial re-orchestration. 1. INTRODUCTION For some years, the automated generation of numerous sound events has been explored using short samples in both granular synthesis [1] and particle systems for audio [2] but only recently has it become possible, with relatively inex- pensive computers, to work with sources of longer duration. Audio Spray Gun [3] is an experimental tool for fixed- media composition that simultaneously generates and spati- alises large groups of such sources, all derived from a single sound sample (typically between 250ms and a few seconds in duration). In this approach to spatial sound synthesis [4], events are created as points constrained by a locus or ‘parti- cle zone’ [5] within a virtual parameter space. By transform- ing this locus over time, the program produces a sequence of events, which can then be rendered to multichannel audio. While earlier versions of the program were designed to render audio direct to eight-channel surround, version 0.8 has been extended to include three-dimensional spatialisa- tion and the option to store sound-groups as metadata for later modification. This paper describes the program and discusses the implications of these developments for editing and spatial re-orchestration [6]. 2. AUDIO SPRAY GUN Audio Spray Gun is so named for its similarity to the spray gun function common to many computer graphics programs in which dots are distributed at random within a moving locus on a canvas. However, because the program operates in a time-based medium, its desired output is a collection of events constrained by the trajectory and transformation of the locus rather than a final static image. 2.1 Parameter Space Audio Spray Gun 0.8 operates in a six-dimensional space comprised of three spatial dimensions, inter-onset interval (delta time), resampling rate and image spread (for use with Vector Based Amplitude Panning or VBAP [7, 8]). The program generates groups of points or sound-events within this space using simple rules that constrain otherwise ran- dom parameter choices to a specific locus which may be transformed over time by means of expansion, contraction and translation. 2.2 Sound-Events Figure 1: A Sound-Event Each sound-event generated by the program is described by seven parameters (figure 1): the file name of the sample to be played by the event plus six co-ordinates describing its position in the space. Each event is stationary within the parameter space and has no spatial or spectral trajectory (for example, panning or pitch bend) of its own. Copyright: © 2015 Richard Garrett. This is an open-access article distributed under the terms of the Creative Commons Attribution Li- cense 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. ICMC 2015 – Sept. 25 - Oct. 1, 2015 – CEMI, University of North Texas – 352 –