This video, via demjp8RqDA, shows a solid-state Tesla coil “singing”.
Here’s an explanation of how it works:
The primary runs at its resonant frequency in the 41 KHz range, and is modulated from the control unit in order to generate the tones you hear. It is the actual high voltage sparks that are making the noise. Every cycle of the music is a burst of sparks at 41 KHz, triggered by digital circuitry at the end of a “long” piece of fiber optics.
What’s not immediately obvious in this video is how loud this is. Many people were covering their ears, dogs were barking. In the sections where the crowd is cheering and the coils is starting and stopping, you can hear the the crowd is drowned out by the coil when it’s firing.
The Tesla coil was built and is owned by Steve Ward, an EE student at U of I Urbana-Champaign.
The coil has been nicknamed “thoremin”, and yes – somebody did yell “Play Freebird” at the demonstration.