I have visited an event once and there was people who were shocked to see music coming from tesla coils. They didn't have any idea why does it make music so efficiently. Actually, the reason is tesla coil is converting air into plasma, changes its volume and this cause waves spreading out in all direction. Then these waves controlled by MIDI sequenced which you have already mentioned in your posts sir.
So, I am sure now, whoever reading this post, would never wonder about it.
Anyways children are having a good time inside the cubicle :) Good to see them happy :)