There might not be any air in space, but NASA scientist and astronaut Don Pettit has come up with a way of showing how waves act in microgravity. He's currently aboard the International Space Station, acting as its science officer, and has used a USB-powered speaker with a drop of water to demonstrate the physics of sound. By sending sound to the speaker, with the droplet bound only by surface tension, Pettit shows how the vibrations ripple through the water with close-up video of each wobble and warp of the drop.
The overall effect is like a makeshift oscilloscope, with higher frequency sound forcing beads of water from the drop. It's also a little reminiscent of a Rubens flame tube, where a line of flaming gas jets are manipulated using sound waves. Watching the droplet ripple is hypnotic, with the conflicting pulses form the speaker creating a brain-like texture to the sound's surface.