Application of Wave Field Synthesis in the composition of electronic music

Page  00000001 Application of Wave Field Synthesis in the composition of electronic music M.A.J. Baalman, M.Sc. Electronic Studio, Technical University, Berlin, Germany email: baalman@kgw.tu-berlin.de Abstract Wave Field Synthesis offers new possibilities for composers of electronic music to add the dimension of space to a composition. Unlike most other spatialisation techniques, Wave Field Synthesis is suitable for concert situations, where the listening area needs to be large. It is shown that an affordable system can be built to apply the technique and that software can be written which makes it possible to make compositions, not being dependent on the actual setup of the system, where it will be played. Composers who have written pieces for the system have shown that with Wave Field Synthesis one can create complex paths through space, which are perceivable from a large listening area. 1 Introduction Spatialisation1 has been a topic of interest in the development of electronic music since the 1950's; common techniques make use of quadraphonic or octaphonic setups and are based on providing localisation cues based on psycho-acoustics or acoustics (e.g. Chowning 1971). The technique of ambisonics has become popular since the 1990's (e.g. Malham and Matt 1995). There are also various examples where more loudspeakers are used, mostly as setups for one specific piece or location and not as a standardardized setup. A detailed historical overview of spatialisation techniques can be found in Malham & Matt (1995). The limitation of stereo or ambisonic techniques is that it only works perfectly well for one listener, who is positioned on the so-called "sweet spot". Obviously, in common concert environments the intended effect of movement of the sound will in these cases not be heard by a majority of the listeners. Wave field synthesis is a technique that can overcome the limitation of only working well for one "sweet spot" and can provide a good perceptual 'In this paper no comparisons are made to headphone techniques, as these techniques are quite different from loudspeaker techniques by principle and less suitable for concert situations. localisation in a relatively large listening area. This makes the techique ideal for concert environments. Its increasing popularity in audio engineering shows that it is not unlikely that the technique will be available in concert halls and becomes affordable for studios in the near future (see CARROUSO2). This article describes the first experiences with the application of wave field synthesis in the composition of electronic music. A short, comprehensive explanation of the technique is given, a description of the system used in the project at the TU Berlin and the interface software, followed by a description of the possibilities that were used by composers. The pieces described were presented on the Club Transmediale Festival in Berlin, on the 4th of February 2003. 2 Wave Field Synthesis The concept of Wave Field Synthesis (WFS) is based on a principle that was thought of in the 17th century by the Dutch physicist Huygens (1690) about the propagation of waves. He stated that when you have a wavefront, you can synthesize the next wavefront by imagining on the wavefront an infinite Figure 1. The Huygens' Principle 2 CARROUSO (Creating, assessing and rendering in real-time of high-quality audio-visual environments in MPEG-4 context), http://emt.eemtiis.fhg. de/proj ects/carrouso/