I have for some time wanted to experiment with high-voltage; specifically a Tesla Coil. Recently, a Massachusetts company called OneTesla has started offering relatively inexpensive kits to build a type of coil called a DRSSTC, or Dual Resonant Solid-State Tesla Coil. This design of coil can produce a visually impressive display of streamer arcs from a comparatively low input power.
The nature of DRSSTCs allows the interruption of their streamer arcs within audio-frequency ranges. This allows DRSSTCs to act as speakers, using the rapid heating and cooling of the air surrounding the arcs to generate sound waves in the air. Even a low-power small coil such as this can be extremely loud.
In order to control the audio of the Tesla Coil, a specially designed USB Midi device which outputs signals over a Fibre-optic connection is used. This in my opinion is not a great solution, as the device requires a laptop to control it. I plan to design a standalone controller using an SD card to store files for playback and control dials for volume and frequency. An additional feature of this controller will be a MIDI input port, to enable live playback on a MIDI keyboard for example to the coil.