Due to my innate laziness, I am unable to pick up the microphone right now. Perhaps I'll send you a file when I actually manage to.

And by the way, a speaker is an output device. You cannot use it as an input device to record sounds. See http://en.wikipedia.org/wiki/Loudspeaker for more information.

The dynamic principle is exactly the same as in a loudspeaker, only reversed.[...]
A crystal microphone uses the phenomenon of piezoelectricity—the ability of some materials to produce a voltage when subjected to pressure—to convert vibrations into an electrical signal. An example of this is Rochelle salt (potassium sodium tartrate), which is a piezoelectric crystal that works as a transducer, both as a microphone and as a slimline loudspeaker component.
[...]
A loudspeaker, a transducer that turns an electrical signal into sound waves, is the functional opposite of a microphone. Since a conventional speaker is constructed much like a dynamic microphone (with a diaphragm, coil and magnet), speakers can actually work "in reverse" as microphones.