Crossword Dictionary
microphone
A microphone, colloquially called a mic or mike, is a device – a transducer – that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, radio and television broadcasting.
how it works
In a microphone, sound waves (sound-pressure variations in the air) are converted into corresponding variations in electric current in two operations that take place almost simultaneously. In the first, the sound wave impinges on a slightly flexible surface (diaphragm), causing it to move to and fro in a manner corresponding to the movement of the air particles.
In the second, the diaphragm by its motion causes a corresponding change in some property of an electric circuit. Depending on the type of microphone, displacement of the diaphragm may cause variations in the resistance of a carbon contact (carbon microphone), in electrostatic capacitance (condenser microphone), in the motion of a coil (dynamic microphone) or conductor (ribbon microphone) in a magnetic field, or in the twisting or bending of a piezoelectric crystal (crystal microphone).
In each case, motion of the diaphragm produces a variation in the electric output. By proper design, a microphone may be given directional characteristics so that it will pick up sound primarily from a single direction (unidirectional), from two directions (bidirectional), or more or less uniformly from all directions (omnidirectional).