A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. Most microphones use the change of capacitance caused by the diagrapham mechanical vibration to produce an electrical voltage signal. In a condenser microphone, the diaphragm acts as one plate of a capacitor, and the vibrations produce changes in the distance between the plates. There are two types of microphones of this kind: Pre-polarized Microphones and 200V Polarized Microphones.