Capacitor Microphone

Also known as a 'condenser microphone'. This is a specific form of electrostatic microphone which operates on the principle of measuring the change in electrical voltage across a capacitor which contains a constant static charge. The capacitor is formed from two metal electrodes, one fixed (the back-plate) and the other a thin conductive membrane that flexes in response to sound pressure, and the static charge comes either from a DC-bias voltage or a dielectric material. (See also 'Back Electret', and 'RF Capacitor Microphone'.)