So, what is a plasma speaker?
A plasma speaker (or “singing arc”) is a speaker that uses a plasma arc to produce sound. By varying the intensity of the arc, different pressure waves are created. Pressure waves produce sound.
Most speakers use electromagnets to vibrate air to create the sound waves that you hear. The plasma speaker creates sound waves by ionizing the air with a high voltage electric arc. They use atomic-scale particles as the main driver of sound pressure waves as opposed to traditional speaker drivers such as paper cones. The plasma discharge excites the surrounding particles and ions, causing them to collide with neutral air particles. These collisions are what is responsible for the creation of pressure waves that we perceive as sound. Because of this, the plasma speaker possesses some relatively unique properties.