A microphone, sometimes referred to as a mike or mic (both IPA pronunciation), converts sound into an electrical signal.
Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production, live and recorded audio engineering, in radio and television broadcasting and in computers for recording voice.
Sound passes through the air in waves, and as was said above, the microphone turns the sound wave into an electrical wave. Different kinds of microphones will turn the sound waves into electricity in different ways.
Carbon button - This is the first kind to become commonplace, being used in most 20th century telephones. Sound waves, by compressing and decompressing a piece of carbon, change the amount of electric current flowing in the wire, thus creating electrical waves. This kind became rarer late in the century, due in part to lack of high fidelity.

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