Microphone Basics: Polar Pattern
If you need a microphone for a specific situation, it is important to choose a microphone that is suited for the job. There are three characteristics that determine which microphone you should choose: the Transducer Type (read our previous post), Polar Pattern & Frequency Response.
This week we will cover the various microphone polar patterns.
Polar pattern / Directionality
The polar pattern of a microphone is the sensitivity to sound in relation of the direction (or angle) from which the sound arrives. A simple description would be: how well the microphones “hears” sound from different directions. The most common types of directionality are: Omnidirectional, Cardioid and Supercardioid.
A microphone with a cardioid polar pattern has the most sensitivity at the front and is the least sensitive at the back. It isolates from unwanted ambient sound and is much more resistant to feedback than omnidirectional microphones. This makes a cardioid microphone a good choice for loud stages.
Supercardioid microphones offer a narrower pickup than cardioid and a greater rejection of ambient sound. But they also have some pickup directly at the rear. This makes the correct placement of monitor speakers important. Supercardioid microphones are most suitable when single sound sources need to be picked up in loud environments.
A supercardioid microphone is most resistant to feedback.
An omnidirectional microphone has equal output or sensitivity at all angles, it picks up sound from all directions. This means the microphones doesn’t have to be aimed in a certain direction, which is helpful especially with lavalier microphones. A drawback is that an omni cannot be aimed away from unwanted sound sources, such as PA speaker, which may cause feedback.
Bidirectional (Figure of Eight)
Microphones with a figure of eight (bidirectional) polar pattern picks up sound from the front and from the rear of the microphone, but not from the side (in a 90 degree angle). Usually ribbon or large diaphragm microphones have a figure of eight polar pattern.
Symbols for Polar Patterns
A visual comparision of polar patterns.