Transducers are devices which convert energy from one form to other. A microphone is a transducer which converts sound energy to electrical signals. It works opposite to a speaker. Microphones are available in different shape and sizes. Depending on the application, a microphone may use different technologies to convert sound to electrical signals. Here we are going to discuss about the Electret Condenser Microphone which is widely used in mobile phones, laptops, etc.Electret Condenser Microphone, as the name suggests is a parallel plate capacitor and works on the principle of a variable capacitance. It consists of two plates, one fixed (called the back plate) and the other moveable (called Diaphragm) with a small gap between them.