3-D Sound Spatialization using Ambisonic Techniques

The exploration of sound spatialization is a preoccupation of many composers and performers of electroacoustic music. Two-channel stereo techniques are widely used in the genre, but more sophisticated forms of sound spatialization are often restricted to those with access to significant technical resources. Recent technological developments have increased access to high-quality, multichannel audio systems and computer music workstations, and new applications for sound spatialization have been identified: virtual reality, multimedia computing, films, videos, and computer games may all employ surround-effects of some type. In addition, increased computing power has led to the production of workstations that can support the data bandwidth required for multiple audio channels. All of these factors have led to a renewed interest in sound spatialization techniques, providing enormous potential for accelerated development of the field. Ambisonics is a powerful technique for sound spatialization. It can allow recording, manipulation, and composition with naturally and artificially constructed three-dimensional sound fields. In this article we will present the results of experimentation and research into the application of ambisonics to the composition and performance of electroacoustic music. We also present Csound implementations of ambisonic encoding and decoding techniques that can be used on any computing platform supporting four or more independent audio output channels. Our hope is that these techniques will be a useful resource for those wishing to experiment with sound spatialization, and that their presentation here will encourage further developments. This article examines a variety of spatialization t hniques within a historical and technical cont xt, identifying some of the advantages and disadvantages of specific methods. This provides the basis for a review of ambisonic theory, which additionally describes several advanced spatialprocessing methods that are possible with this technique. We go on to discuss experimental results and compositional considerations related to the use of ambisonic techniques for electroacoustic music performance.