swiped from link below:
Those that can produce a continuous spark output (that is, a flame
like plasma that exists at 100% duty cycle) and those that make what
appear to be a continuous spark, but are rather producing sparks at
several hundred times per second with a rest between each spark
event. The first (continuous) type of SSTC lends itself to audio
modulation. Normally the output spark is a silent plasma flame. By
modulating the amount of power put into the plasma flame, we can
modulate the physical volume of the plasma. Modulating the size of
the plasma will cause the expansion/relaxation of air surrounding the
plasma, thus producing sound waves. These have actually been around
for decades using vacuum tube drive. See this link for more details:
http://www.stevehv.4hv.org/MusicalSSTCs.htm
Enjoy,
Chris Titan
http://altsciencediscussion.blogspot.com/
