Boss BR-1180 User Manual page 6

Microphone Directionality.
A mic's directionality helps determine its usefulness in a specific recording environment.
You can tell how a mic will "hear" by noting its pickup or polar pattern. There are three
basic types of pattern.
Omnidirectional
An omnidirectional (or omni) microphone is sensitive to sound a full 360 degrees around
the head of the mic, its capsule. Omnidirectional microphones are good for recording
room sound.
Unidirectional
A Unidirectional microphone captures most of its signal from one direction, the front.
The most common type of unidirectional microphone is called a cardioid, based on its
heart-shaped pickup pattern.
There can be variations in cardioid patterns. A hypercardioid pickup pattern will register
sound from its front at greater distances but less from its sides. This provides a more
narrow pattern than a cardioid A supercardioid mic registers sound at great distances
from its front but is also sensitive from its back yet picks up almost nothing from its
sides. These "special" types of cardioid mics can be useful for capturing sound without
being close to its source.
In general a unidirectional microphone is most often used for recording sounds that need
to be isolated, such as vocals, guitar amps, woodwinds etc. It is the most commonly used
mic in recording.
Bi-directional
A bidirectional microphone is equally sensitive to sound from both the back and front.
This type of mic is often used for capturing the sound of two vocalists facing each other.
And finally, a multidirectional microphone uses multiple diaphragms. This will allow
you to switch to between different pickup patterns.
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