oscillation when you move your fingers near a capacitor...

[Hal]

sometimes, expecially in high gain circuits (MULTIFACE) a nasty humming is herad when you grab the input/output cap, or just move your fingers near it.  What causes this?

my hypothesis: the electrical field generated by the caps induces a bipole in your fingers, so the capacitor becomes stronger, or something like that...??

[niftydog]

ever read up about how a theramin works?

Your body is a fantastic conductor of electricity; it also generates it's own electricity. In high gain circuits, any induced noise is amplified massively.

I'd say it's a combination of the effect you mentioned (body capacitance) and you body acting as an antenna for noise and channeling it into the circuit.