Re: Pedantically...
A speaker is a mic. Just as a mic is a speaker.
That is one of those things that strike me as having been seen on Doctor Who, MacGyver or whatever with no real idea of the practicalities. Seriously, you are not going to get any useable signal out of a moving coil speaker used as a mic even if the surrounding circuitry could theoretically read it. And as for getting any sound at all from a condenser mic, forget it completely.
Biting the hand that feeds IT
