Tip #2:
Microphone Polar Patterns

(also called pickup patterns or directional patterns)

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A polar pattern is a graph of a microphone's sensitivity vs. the angle of the incoming sound wave.

The farther from center a point on the graph is, the stronger is the mic signal at that angle.

  Omnidirectional: Picks up equally in all directions. 7pts-Omni.gif (2306 bytes)
  Half-omnidirectional or hemispherical: Picks up equally over a 180 spherical angle. This is the pickup pattern of PZMs. 7pts-Halfomni.gif (1843 bytes)

All of the following patterns are considered unidirectional because
they pick up mainly in one direction.

  Cardioid: “Heart-shaped” pattern that offers maximum rejection (null) at the rear of the microphone. 7pts-Cardioid.gif (2773 bytes)
  Supercardioid: Has a narrower pickup pattern than cardioid, but also has some rear pickup. Note that there are two nulls of maximum sound rejection. 7pts-Superc.gif (3003 bytes)
  Hypercardioid: Has a narrower pickup pattern than supercardioid, but also has more rear pickup than supercardioid. Note that there are two nulls. 7pts-Hyperc.gif (3075 bytes)
  Half-unidirectional: The pickup pattern of PCC microphones. 7pts-Halfcard.gif (1699 bytes)
Bidirectional (figure-eight or cosine): Picks up mainly in two directions (in front of and behind the mic) and rejects sound from the sides.


Traits of Different Polar Patterns

Omnidirectional
All-around pickup
Most pickup of room reverberation
Not much isolation unless you mike close
Low sensitivity to pops (explosive breath sounds)
No up-close bass boost (proximity effect)
Extended low-frequency response in condenser mics. Great for pipe organ or bass drum in an orchestra or symphonic band.
Lower cost in general

Unidirectional (cardioid, supercardioid, hypercardioid, hemispherical, half-cardioid, half-supercardioid)
Selective pickup
Rejection of room acoustics, background noise, and leakage
Good isolation--good separation between recorded tracks
Up-close bass boost (except in mics that have holes in the handle)
Better gain-before-feedback in a sound-reinforcement system
Coincident or near-coincident stereo miking
Broad-angle pickup of sources in front of the mic
Maximum rejection of sound approaching the rear of the mic

Supercardioid
Maximum difference between front hemisphere and rear hemisphere pickup (good for stage-floor miking)
More isolation than a cardioid
Less reverb pickup than a cardioid

Hypercardioid
Maximum side rejection in a unidirectional mic
Maximum isolation--maximum rejection of reverberation, leakage, feedback, and background noise

Bidirectional
Front and rear pickup, with side sounds rejected (for across-table interviews or two-part vocal groups, for example)
Maximum isolation of an orchestral section when miked overhead
Blumlein stereo miking (two bidirectional mics crossed at 90 degrees)