This is a demonstration of a kid-powered “Drum Panel/Synthesizer” for playgrounds:
“Buttons” are simple regions of plastic shaped in circles with vibration sensors. A wavelet analysis bank is used to separate “hits” in a specific location from random structural vibrations and hits that may have happened elsewhere.
It also has a cool voice/rhythm record mode. After the first demo of the voice record/ playback the unit runs out of juice. One gets anywhere from 45-seconds to 3 minutes depending on how the unit is used.
This is more of a sample playback device than a synth, but the hand-cranked kid-powered action is pretty sweet.