A microphone’s polar pattern is the sensitivity of how well the microphone receives sound relative to the angle or direction of where the sound originates.
In simpler terms, a microphone’s polar pattern is how well the microphone can capture sound from various directions.
Polar patterns are essentially directionality presets with Cardioid, Supercardioid and Omnidirectional patterns being the most common types of directionality.
A cardioid microphone is designed to have the most sensitivity in front and the least sensitivity at the back. A cardioid microphone is very efficient in isolating unwanted ambient sound and focuses on the main source – this is suitable for loud stages. However, also makes it a lot more susceptible to live feedback compared to other polar patterned microphones.
Supercardioid microphones are as the name implies – the super version of cardioid microphones. A supercardioid focuses a lot more on the main voice feed than cardioid and has an even greater rejection of surround or ambient sound.
Unlike the cardioid microphone, however, the supercardioid is able to pick up some sound directly at the back. With supercardioids, monitor speakers must be placed correctly to avoid collecting feedback.
An omnidirectional microphone or ‘Omni’ is able to capture sound from any angle – this is because Omnis have equal sensitivity at every angle. A microphone with omnidirectional polar pattern does not have to be positioned or directed a certain way to capture sound because it is designed to capture both the direct feed and the ambient sound thus making it very helpful especially in the case of lavalier microphones.
A downside to Omni, however, is that they cannot be aimed away from undesired sources like Public Address speakers and this would cause feedback.
Bidirectional or Figure of Eight
A microphone designed with a figure of eight polar pattern picks up sound from the front of and the rear of the microphone but would isolate sound to its sides.
Examples of microphones with this polar pattern are typically large diaphragm or ribbon microphones.