13were dispersed. This began with research into the psychoacoustics of human hearing, leading to more accurate pan-pot laws for stereo panning [3], and were furthered again in the 1990s with developments in vector-base amplitude panning [4], wave field synthesis and higherorder ambisonics. The new technologies encouraged new spatial aesthetics, allowing composers to conceive spatialization through a focus on the creation of holophonic sound fields and phantom sources.Tools for the control of spatialization algorithms found their way into digital audio workstations, allowing the composer to drag a virtual representation of a sound object and place it within a speaker array. The amplitude mapping of faders was counterintuitive for pantophonic motion (i.e. circular spatial trajectories): Most spatial user interfaces became graphical. In spite of this, the mixing desk continued to be the user interface for diffusion performance. With composers thinking and acting one way in the studio and another in the concert hall, the paradigm was ripe for disruption. In the studio, composers have as much time as needed to place sounds precisely where desired and to trace out specific trajectories with the mouse onscreen. In performance, the luxury of time is diminished, and gestural relationships become more relevant. The holophonic sound field and its effect on a composer's way of thought emphasized the need for a new performance interface, as the ergonomics of the mixing desk often hinder the potential trajectories available to the performer. This problem a b s t r a c t Wi th the ascendance of the field of new interfaces for musical expression, a new phase of sound diffusion has emerged. Rapid development is taking place across the field, with a focus on gestural interaction and the development of custom performance interfaces. This article discusses how composers and performers embracing technology have broadened the boundaries of spatial performance. A particular focus is placed on performance interfaces built by the author that afford the artist more control over performative gestures. These new works serve as examples of the burgeoning field of diffusion performance interface design.Bridget Johnson (researcher, student), New For over half a century, the performance paradigm of sound diffusion has centered on the performer using a mixing desk as a controller. While much development has taken place regarding studio spatialization techniques and rendering algorithms, until recently the performance interface for diffusion has seen little change. A recent trend in diffusion performance is the application of new musical interfaces.
HistoryIn 1951, Pierre Schaefer and Pierre Henry presented the potentiomètre d'espace, a diffusion system with which they performed precomposed electroacoustic music by dynamically spatializing sounds through a tetrahedral speaker array. The two artists built an interface of potentiometers to control the gain of each speaker and, thus, the spatial field [1]. The diffusion concert is a tradition that r...