What you see here is audio in 3D space! You are seeing audio.
Sound is a manifestation of pressure fluctuations caused by a moving body (i.e. a diaphragm in a speaker) causing pressure waves to propagate through the air! Waves are sinusoidal and have a peak and a trough in every cycle. They can interact with one another as they bounce around the surrounding.
Forcing the pressure fluctuation to go through another medium (like water here) will create those same exact waves in a much thicker medium, and it creates the peaks and troughs, just like a wave. Using a micro-controller, the light reflected off these peaks and troughs create beautiful geometrical patterns, since sound travels radially outwards!