This is a polyphonic synthesizer made schmitt-trigger oscillators. Signals from each Individual oscillator is transfered through finger/flesh and into the mix. This also make it super noisy.
Conductive Touch synthesizer
The circuit for this projects is very simple. 12 schmitt-trigger oscillators are all connected to different copper-pads, which line up with copper-pads going to the output-mix. When both copper-pads are touched by skin or other conductive material, the singal goes though to the mix and the sound can be heard.
Since the mixer has a lot of unconnected parts when not touching anything a lot of noise i coming out of the amp (i used a LM386, maybe a less noisy application?).
I tried putting a capacitor on the mixed signals, this seems to be making the signal sort of weak but more soft and less noisy.