At the heart of any recording setup is the microphone, and one of the key characteristics that determine its performance is its polar pattern. A polar pattern is a graphical representation of the microphone's sensitivity to sound from different directions. Understanding polar patterns is essential for achieving optimal audio quality and avoiding common mistakes that can compromise the recording.
What is a Polar Pattern?
A polar pattern is a two-dimensional plot that shows the microphone's directional response to sound waves from different angles. The most common polar patterns are omnidirectional, cardioid, supercardioid, and figure-of-eight. Each pattern has a unique shape that reflects the microphone's sensitivity to sound from different angles.
An omnidirectional microphone picks up sound equally from all directions, making it ideal for recording ambient sound or natural acoustics. A cardioid microphone, on the other hand, is more directional and suppresses sound from the rear and sides, making it suitable for capturing individual sources in noisy environments. A supercardioid microphone is even more directional and has a narrower pickup angle than a cardioid, making it useful for isolating individual sources in highly reverberant spaces. Finally, a figure-of-eight microphone has a bidirectional polar pattern and picks up sound from the front and back while rejecting sound from the sides.
There are three main categories of directional properties for microphones:
Omnidirectional
These microphones can capture sound of equal quality from all directions, including the direct and ambient sound. Despite capturing surrounding sound, the use of these microphones is typically for close miking to minimize unwanted noise. The sound reproduces by the omnidirectional microphone such as SEM-01 and SEM-02 are natural. The application of SEM microphone is close miking, so the unwanted sound can be minimized in volume and more signal is accepted.
2. Unidirectional
This category includes cardioid and hyper-cardioid microphones, which primarily pick up sound from one direction.
– Cardioid
Capture sound mostly from the front and a little area on the side, rejecting sound mostly from behind the capsule. They are versatile and ideal for general use.
Typical handheld dynamic microphone usually has a cardioid polar pattern.
The cardioid-type mic is very flexible and ideal for general use. Most handheld mics are cardioid. There are many variations of the cardioid pattern (including the hyper-cardioid described below).
– Hypercardioid
Hyper-cardioid microphones are highly directional and eliminate most side and rear sound, making them suitable for isolating sound from only one subject or direction when there is a lot of ambient noise. Because of the hyper-cardioid design that is thin and long, this type of microphone is often called a shotgun microphone.
It is usually used to isolate sound from only one subject or one direction when there is a lot of ambient noise, to capture sound from distant subjects.
There is also a hand-held mic that has a super-cardioid (hyper-cardioid) polar pattern
By eliminating ambient noise, the sound from one direction of the cage becomes less natural. Inserting audio recordings from other mics will help (e.g. constant background noise at low volume)
Care needs to be taken to maintain the consistency of the sound. You will lose audio if the mic is not always aimed at the subject.
– Lobar
The shotgun shape can increase the sensitivity to the rear area. Hence, the sound reproduced is less natural and has a certain coloration to the audio captured.
3. Bidirectional
These microphones can capture sound from two opposite directions and use a figure-eight pattern to pick up sound evenly from both directions.
These microphones are rarely used, but they are useful for situations like interviewing two people facing each other where the mic is between them
In some cases, the shape of the microphone can affect its directionality, with shotgun microphones having a more directional pattern. Additionally, the use of certain microphones with different directional properties can be combined with other miking techniques, such as M/S (mid-side) technique.
So that are the polar patterns in the microphone. Hopefully, you get the idea now.
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