Microphone

A microphone, sometimes called a mic (pronounced "mike"), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production and in radio and television broadcasting.
The invention of a practical microphone was crucial to the early development of the telephone system. Emile Berliner made-up the first microphone on March 4, 1877, but the first helpful microphone was invented by Alexander Graham Bell. Many early developments in microphone design took place in Bell Laboratories.
In all microphones, sound waves (sound pressure) are translated into mechanical vibrations in a thin, flexible diaphragm. These sound vibrations are then converted by various methods into an electrical signal which varies in voltage amplitude and frequency in an analog of the original sound. For this reason, a microphone is an acoustic wave to voltage modulation transducer.