The video above is ArcAttack! playing the classic “Popcorn” through their signature Tesla coils. Solid state Tesla coils (SSTC) can generate sound using what [Ed Ward] calls pulse repetition frequency (PRF) modulation. The heat generated by the plasma flame causes rapid expansion of the surrounding air and a resulting soundwave. An SSTC can be operated at just about any frequency, so you just need to build a controller to handle it. The task is made more difficult because very few electronics are stable in such an intense EM field. [Ed] constructed a small Faraday cage for his microcontroller and used optical interconnects to deliver the signals to the Tesla coils.
[via Laughing Squid]