A microphone is a device that converts a physical vibration (such as sound) into an electrical signal, that can be stored and/or processed.
In the sound industries, microphones are usually the very first device in the production chain. This makes them an extremely important part of the process.
Microphones interact with the physical world, turning kinetic energy into electrical energy. The kinetic energy is in the form of pressure variations in the given medium (e.g. Air), which is transferred to the microphone's element. This energy induces a varying electric current which is analogous to the original variation in the medium. The current is induced via different means for different microphone types. How precisely the original sound is represented by a microphone is known as the fidelity.
A device which converts variations into an electronic signal and vice versa, is called a transducer. This means that a speaker is also a form of transducer.
Microphones come in all shapes and sizes and can capture anything from a simple human voice to sounds inaudible to the human ear.
There are three main types of microphone;
Each of these microphone types are suitable for different situations. Dynamic microphones are more robust while condenser microphones are more sensitive; physically as well as acoustically. Piezoelectric microphones are good for capturing sound in challenging environments, like underwater.