I did write it myself actually. The sound sample itself is just a simple sine synth, and there's a few audio processing effects on the output (reverb, compressor).
The quality of the sound is using some data from the simulation.
- Scale is a pentatonic variation chosen depending on the color of the background (darker is more minor)
- Octave is determined by the color of the spokes
- Pitch is determined by the Y position
- Panning is controlled by X position
I basically just tried to figure out the most natural mapping to the sound properties I had readily available to tweak. Most of those parameters are accessible on Unity's AudioSource