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There are a number of well-developed microphone techniques used for recording musical, film, or voice sources or picking up sounds as part of sound reinforcement systems. The choice of technique depends on a number of factors, including:
- The wish to capture or avoid the collection of extraneous noise. This can be a concern, especially in amplified performances, where audio feedback can be a significant problem. Alternatively, it can be a desired outcome, in situations where ambient noise is useful (hall reverberation, audience reactions such as cheering).
- Degree of directionality of pickup: in some settings, such as a home video of a birthday party, the person may wish to pick up all the sounds in the room, which would make an omnidirectional mic desirable. However, if a TV news crew is filming a reporter at a noisy protest, they may only wish to pick up her voice, making a cardioid mic more desirable.
- Choice of a signal type: Mono, stereo or multi-channel.
- Type of sound-source: Acoustic instruments produce a sound very different from amplified electric instruments, which are again different from the human voice.
- Sound pressure levels: a mic that is recording Baroque lute will not face high sound pressure levels, which could lead to distortion; on the other hand, a mic being used to record heavy metal drumming or low brass may face extreme sound pressure levels.
- Situational circumstances: Sometimes a microphone should not be visible, or having a microphone nearby is not appropriate. In scenes for a movie the microphone may be held above the picture frame, just out of sight. In this way there is always a certain distance between the actor and the microphone.
- Processing: If the signal is destined to be heavily processed, or mixed down, a different type of input may be required.
- The use of a windshield as well as a pop shield, designed to reduce vocal plosives.