N » 2: Multi-speaker Display Systems for Virtual Reality and Spatial Audio Projection

This paper describes multi-speaker display systems for immersive auditory environments, collaborative projects, realistic acoustic modeling, and live musical performance. Two projects are described. The sound sub-system of the Princeton Display Wall project, and the NBody musical instrument body radiation response project. The Display Wall is an 18' × 8' rear-projection screen, illuminated by 8 high-resolution video projectors. Each projector is driven by a 4-way symmetric-multi-processor PC. The audio sub-system of this project involves 26 loudspeakers and server PCs to drive the speakers in real time from soundfile playback, audio effects applied to incoming audio streams, and parametric sound synthesis. The NBody project involves collecting and using directional impulse responses from a variety of stringed musical instruments. Various signal processing techniques were used to investigate, factor, store, and implement the collected impulse responses. A software workbench was created which allows virtual microphones to be placed around a virtual instrument, and then allows signals to be processed through the resulting derived transfer functions. Multi-speaker display devices and software programs were constructed which allow real-time application of of the filter functions to arbitrary sound sources. This paper also discusses the relation of spherical display systems to conventional systems in terms of spatial audio and sound-field reconstruction, with the conclusion that most conventional techniques can be used for spherical display systems as well.