Plasma speaker

A plasma speaker is a device that generates an high voltage vibrating electrical arc that makes sound. The main problem with these speakers is that they many need a continuous supply of ionizable gas. The plasma has a by-product which we all know: Ozone, and if left in a closed room for long periods of time, it can reach hazardous levels!

By sending more current through an arc, you produce a hotter arc. Hotter arcs will have a higher pressure, and by varying the current through an arc you create varying pressures, something commonly known as sound.