Voice of Fire (2003)
In 2003, Tim Black built the Voice of Fire project and took it to Burning Man. Voice of Fire incorporated 13 plasma speakers into a unique case (see Playa Pictures below). Participants would speak into a microphone and hear their words (and the words of others) come back to them through individual speakers, sometimes right away, other times after a delay or with some effect added to the sound.
A plasma speaker is an omni-directional speaker created by modulating a plasma arc using a sound wave. To make it easier to create and maintain the arc, the arc is bathed in an ionized flame. The flame provides a steady conductor for the plasma and makes it appear as if the fire is talking. The Video Clips show a plasma speaker in action.