I thought that I could get some audio output from doing this: I cut a 6-inch hole in the back of a tablet (thin cardboard) and taped 7x7 pieces of tinfoil on each side so the 2 foils were maybe 1mm apart. Then I connected a 9V battery to the 2 sides through a 5Meg resistor. I connected my scope to the 2 foils and clapped my hands and expected some audio output, but couldn't observe any. Am I off base on this?