Polar Patterns Explained
What are those strange and cryptic pictures on my microphone? One of them looks like a mushroom…. This article is all about microphone polar patterns – what are they? Why have different patterns? Which one should I use? All will be revealed…
Where do microphones pick up from?
Before we go into detail on polar patterns, it is important to understand what type of mic you have and which way its diaphragm is oriented.
The first type is the classic SM58 shaped mic. These are used like a torch (flashlight to those in the states) as they pick up sound head on – just point it at the sound source.
The second type is the “side-firing” microphone like AKG’s C414 or the Neumann TLM-103. These sit upright and pick up sound from the sides.
Types of Polar Patterns
Cardioid
Cardioid microphones are directional have a heart shaped polar pattern. This means they pick up sound mainly from the front and are least sensitive to sound from the rear (its null point).
As they pick up less sound from behind they can be positioned to pick up the instruments that you want to record and “ignore” the other sounds that you don’t want. For example if you are recording guitar in a room with a noisy PC, you can aim the mic at the guitar and make sure the mic’s null point is facing the PC.
Cardioid mics do have problems though. Due to their construction, they exhibit the phenomenon known as the proximity effect. The microphone boosts the bass frequencies when it is close to the object it is recording, resulting in a boomy sound. Some cardioid microphones can also produce a nasal quality in some vocals.
Hyper-cardioid
Hyper-cardioid microphones have a similar pick up pattern to the cardioid mics but are more directional and don’t pick up as much from the side.
Hyper-cardioid microphones are good at separating specific sounds from multiple sound sources. They are tightly focussed and are good for miking up drum kits as they can concentrate on specific drums and reject spill from other sources such as cymbals. Hyper-cardioid mics do have a “hyper-cardioid tail” which means they do pick up sound directly behind them.
Figure of 8 (bi-directional)
Figure of 8 microphones pick up from the front and rear and have null points to either side.
They are good for recording two vocalists facing each other or for recording something and still capturing the ambience of the room. Figure of 8 microphones don’t exhibit any proximity effects.
Omni directional
Omni directional microphones are sensitive to sound from all directions.
Omni mics are good for picking up the ambience and reverb of rooms and tend to sound very natural and open even when placed close to instruments. Omni microphones don’t exhibit any proximity effects but obviously are not good when separation is needed.
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Jon Maskrey
15 March 06
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