Headphones as a Microphone

If you understand how a microphone and a speaker work, this makes sense. Both have a diaphragm of some sort with an magnet attached. The magnet moves inside of an electromagnet. In a microphone when sound hits the diaphragm it moves causing the magnet to move inside of the electromagnet and generating a small amount of electricity, which is then read as a signal by some kind of device (tape recorder, computer, etc.). In a speaker when you play a sound an electrical signal is sent to the speaker which then creates a magnetic field around the electromagnet, causing the magnet attached to the diaphragm to move which then moves the air. They are just the reverse process of each other.

I tried it with two difference sets of headphones I have. The most expensive of the two cost $20, but it works in a pinch. I found the over the ear headset worked better than the earbuds. That is probably due to the fact that they have a larger surface area. Anyway, pretty cool.