content: It's possible to use a speaker as a microphone, yes. But they generally make terrible microphones. The current induced by sound waves acting on the drivers is far less than the current required for them to actually produce sound themselves. Not to mention the diaphragm design for producing good sound is much different than that needed to record quality sound. I have a pair of decent studio monitors that I tried this with one time. Plugged them into the mic-in jack. I basically had to yell into one of the cups at very close range to get anything even approaching intelligible speech.