This is an _incredibly_ well-crafted piece of work. I mean -- my god -- the pressure wave animation? [1]
1: http://jackschaedler.github.io/circles-sines-signals/sound.h...
1: http://jackschaedler.github.io/circles-sines-signals/sound.h...
The actual air molecules are moving at a much higher speed (the root mean squared velocity is dependent on the temperature). But if we imagine that these are weightless dust particles suspended in air, the diagram is accurate.