A microphone’s polar pattern is the sensitivity of how well the microphone receives sound relative to the angle or direction of where the sound originates.
In simpler terms, a microphone’s polar pattern is how well the microphone can capture sound from various directions.
Polar patterns are essentially directionality presets with Cardioid, Supercardioid and Omnidirectional patterns being the most common types of directionality.
A cardioid microphone is designed to have the most sensitivity in front and the least sensitivity at the back. A cardioid microphone is very efficient in isolating unwanted ambient sound and focuses on the main source – this is suitable for loud stages. However, also makes it a lot more susceptible to live feedback compared to other polar patterned microphones.
Supercardioid microphones are as the name implies – the super version of cardioid microphones. A supercardioid focuses a lot more on the main voice feed than cardioid and has an even greater rejection of surround or ambient sound.
Unlike the cardioid microphone, however, the supercardioid is able to pick up some sound directly at the back. With supercardioids, monitor speakers must be placed correctly to avoid collecting feedback.
An omnidirectional microphone or ‘Omni’ is able to capture sound from any angle – this is because Omnis have equal sensitivity at every angle. A microphone with omnidirectional polar pattern does not have to be positioned or directed a certain way to capture sound because it is designed to capture both the direct feed and the ambient sound thus making it very helpful especially in the case of lavalier microphones.
A downside to Omni, however, is that they cannot be aimed away from undesired sources like Public Address speakers and this would cause feedback.
A microphone designed with a figure of eight polar pattern picks up sound from the front of and the rear of the microphone but would isolate sound to its sides.
Examples of microphones with this polar pattern are typically large diaphragm or ribbon microphones.
All directional microphones have a proximity effect. When the microphone moves closer to the source of the sound, there is an increase in bass response which means a warmer sound is released – this is the proximity effect. In simpler terms, the proximity effect is the change in sound that we experience when we bring the microphone closer to our lips.
Now that we have all these definitions and descriptions out of the way, the next thing to do would be to talk about when and how each polar pattern would be most effective.
When should I use Cardioid?
It’s a no-brainer to see why cardioid mics are best suited for vocals – it records a specific location, and isolates everything else. There are also some not so obvious instances where using a cardioid mic might be useful:
– Micing a drum kit – A drum kit has so many sources of sound in close proximity to each other and this makes isolation of sound challenging. With a selection of cardioid microphones positioned correctly, you can try and avoid as much spill as you can.
– Live performances – During on-stage performances, there is almost no controlling the sounds coming from multiple directions at the same time. Cardioid mics are superb in times like this as they isolate sound and potentially prevent feedback.
Having said all this, cardioid mics also have their shortcomings. The two most obvious issues with cardioids mics would be:
- Off-axis coloration – Moving a cardioid microphone off-axis causes a significant drop in its sensitivity to the main sound source. In simpler terms, if a cardioid mic is moved too far from the singer’s lips, the mic picks up less of their voice and more of whatever it is pointed at. Inexperienced singers, who are unconscious of their head movements during a take, might lose a lot of their vocal audio using cardioid mics.
- Proximity effect – As defined above, the proximity effect is an increase in bass frequencies as a result of close-micing. If an inexperienced singer brings a cardioid microphone too close to their lips, this can be a problem when recording.
While hypercardioid and supercardioid patterns are efficient for filmmaking and off-site recording, they are not exactly suitable for use in a home or professional recording studio.
When should I use omnidirectional polarity?
Prior to the invention of cardioid mics, omnidirectional mics had existed but soon lost their popularity to the cardioids because they “picked up” too much ambient sound and room spill. There are certain situations where omnidirectional mics are a lot more preferable to cardioid mics. For instance:
· When you want to record the sound of the room for ambience. Often referred to as a room mic.
· When you need to record from a wide stereo sound source such as a choir, grand piano or orchestra.
· When you need to record a moving sound source like a brass player or a performing acoustic guitarist.
Omnidirectional mics have:
- More immunity to the proximity effect when compared to cardioid mics
- Lower self-noise than cardioid mics
- Lesser coloration of any off-axis sounds than cardioid mics
When should I use figure-8 polar pattern microphones?
The most common misconception with figure-8 microphones is that they are most suitable for recording a duet of singers when they are facing each other. This may have worked decades ago but it doesn’t happen as much these days.
So when would a figure-8 polar pattern microphone be of use?
- Stereo recording: Figure-8 mics are most suitable for performing mid/side stereo recording techniques, which are appropriate for a number of different instruments. Especially acoustic guitar.
- Isolation: As stated above, figure-8 mics tend to isolate sounds from their sides, hence they are also ideal for recording sound from instruments in close proximity.
- Singer-Songwriters: This polar pattern is perfect for recording singer-songwriters that perform acoustic guitar and sing as if positioned correctly, can maximize the sound captured whilst minimizing spill.
Now that we have a clear knowledge of polar patterns, you will be better placed in future to decide on what works best for you and in what situation you would need a specific selection of microphone.
Choose your weapon.
Image credit: www.shure.co.uk