[beambot]

Actually... some ceramic capacitors are piezoelectric [1] and thus could (conceivably) be used as low-fidelity audio sensors. Better rip out all the capacitors too -- just in case. ;-)

That would be one crazy covert communications channel. Wonder if there are any security papers exploring that...?

[1] http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedback...

[jrockway]

Yes, true. Pretty much any passive device can pick up sound. Two wires running next to each other is enough. A "microphone" is just a particularly well-engineered sound collection device.