Ryan McGee, PhD MAT (2015).
In 1962 Karlheinz Stockhausen’s "Concept of Unity in Electronic Music" introduced a connection between the parameters of intensity, duration, pitch, and timbre using an accelerating pulse train. In 1973 John Chowning discovered that complex audio spectra could be synthesized by increasing vibrato rates past 20Hz. In both cases the notion of increased speed to produce timbre was critical to discovery. Although both composers also utilized sound spatialization in their works, spatial parameters were not unified with their synthesis techniques. Spatial Modulation Synthesis is a novel, physically-based control paradigm for audio-visual synthesis, providing unified control of spatialization, timbre, and visual form using high-speed sound trajectories.
In this performance in the AlloSphere, the sources include a triangle wave (purple), drum samples (orange), and scanned synthesis of the sound trajectory itself (blue). In every case, the visuals represent the trajectory path of the moving sound. Extreme indices of frequency modulation are achieved via physical simulation of Doppler shift, which goes to infinity at the speed of sound.
Here is another video showing Kinetic v3, that utilizes two-voice spatial modulation synthesis: