The sheer number of microphones available to the consumer can cause some confusion. In this article we will provide a brief overview of the different types of microphones and their applications in recording and sound reinforcement as well as provide an overview of some microphone terminology.
The primary types of microphones are the dynamic microphone and the condenser microphone and the ribbon microphone. The terms dynamic and condenser refer to the elements used to convert acoustic energy (sound) into an electric current. In it's simplest sense, a microphone works like the human ear. Sound pressure hits a diaphragm inside of the microphone which causes it to move and create electric voltage. That voltage is sent to another device that will amplify the audio signal or route it to a recording device, etc.
The Dynamic Microphone
Dynamic microphones are known for their reliability and durability. The diaphragm in a dynamic microphone is attached to a coil of wire that is located close to a magnet. When the diaphragm and coil move in relation to the magnet voltage is produced. Dynamic microphones provide excellent fidelity and very stable performance characteristics. The stability of a dynamic microphone enables it to withstand close miking and high sound levels. As a consequence the dynamic microphone is the most popular choice for amplifying live sound.
The Condenser Microphone
The condenser microphone differ from the dynamic microphone in it's diaphragm construction. As apposed to a moving coil the condenser microphone's diaphragm sits parallel to a fixed perforated back plate which creates a capacitor. Sound energy moves the diaphragm and that, in turn, changes the capacity of the circuit which creates electrical output. The response of the condenser microphone is very uniform and they are known for their extended high frequency performance. Due to the extremely high impedance of the condenser microphone they require the use of a preamp (built into the mic and powered by a battery or supplied by a mixer or phantom power supply - 48v). Condenser are the most popular choice for recording and situations nuance is required over massive volume.
Microphone Polar/Pickup Patterns
The two pickup patterns related to microphones are designated as omnidirectional and unidirectional.
The Omnidirectional Pickup Pattern
Omnidirectional microphones pick up sounds from all directions in a fairly equal pattern and will work if the microphone is pointed away from a subject or directly toward a subject. As a consequence, an omnidirectional microphone is more likely to feed back because it will pick up direct loudspeaker sound no matter where the mic is located in relation to the loudspeakers. If the loudspeakers can be located far enough away from the mic, an omnidirectional microphone is often preferred because of it's smoother frequency response, and less susceptibility to breath pops and mechanical shock.
Unidirectional Polar Pattern
Unidierectional microphones are able to reduce or even reject sounds from their sides and rear. They respond best to sounds directly in front of the microphone. The most common variety of unidirectional microphone is referred to as cardioid due to its heart shaped polar pattern. Varieties of the cardioid polar pattern include cardioid, super cardioid, and hyper cardioid. Due to the fact that a cardioid microphone allows you to point the mic away from loudspeakers and work closer to loudspeakers without feedback they work very well in live music situations. A cardioid microphone can reduce noise from random directions by about 67%.
