Mike Lights, Inc. 

Microphone Polar Patterns

Microphones differ in the way they hear sounds. Some are more sensitive than others to certain 
areas around them. This is called the directionality of the microphone. Different pick up sounds 
come from one of three different shaped areas around them. Every different make of microphone 
will have a different directional characteristic.
Omni-directional microphone  Bi-directional microphone
Omni-directional microphones hears sound from all round. These are especially useful in close-up voice reproduction, as they avoid the problem of the speaker or singer having to speak or sing straight into the mic. As long as they are sufficiently near they will pick up the voice.  Bi-directional microphones The catchment area of this type is often referred to as a figure eight. Different bi-directional microphones have different figure eights, some being more sensitive at the front than the back. Unequally balanced figure 8´s are useful for picking up sounds with some added atmospheric sound.
Cardioid microphone  Hypercardioid microphone 
Uni-directional microphones The area of sensitivity in these is roughly heart-shaped or cardioid, but the actual shape varies greatly from make to make. These are most useful microphones in theatre or stage use as they only pick up sound pointed at them, ignoring most unwanted sounds. They are also good for keeping separately-mic'd sounds apart. A variation on this shape is the hyper- cardioid microphone which has a pear-shaped catchment area with a rear pick-up.