Microphone polar patterns explained: Cardioid

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You may have heard of polar patterns, but wonder what it was. So, what is a polar pattern? A polar pattern is a description of the directional sensitivity of a microphone to sound pressure. In other words, the polar pattern of a microphone indicates in which direction(s) the microphone will be more sensitive to picking up sound and in which direction(s) a microphone will reject sound.

A microphone’s polar pattern is a way to display its directional sensitivity. There are some microphones with fixed patterns, while others can switch between quite several different patterns.

Polar patterns are also known as the microphones’ pick-up pattern. The pattern of the microphone shows how well the microphone will responds or pickup sound, depending on the angle from which the sound is coming. The best response angle of a microphone is known as the on-axis response. While the other angles are called off-axis.

The specifications of the polar pattern of a microphone are specified qualitatively and quantitatively in the technical data or specification sheets of the microphone.

Cardioid Polar Pattern

The name cardioid polar pattern was obtained due to its characteristic heart shape. This polar pattern also has three subcategories, which are the supercardioid, subcardioid, and hypercardioid. The cardioid polar pattern is known to have most of its sensitivity to sound in the front and the least sensitivity at the back.

The pickup angle for the cardioid polar pattern is generally 131°. This makes the pickup angle for this pattern quite wide. One of the reasons this is quite useful is because it can accommodate two singers or presenters who wish to use the same microphone. Back-up singers who want to share a single microphone may also use a cardioid microphone. One of the other perks of the cardioid polar pattern is the great feedback rejection.

But that’s not all, the 131° polar pattern also means broadcasters who sing or talk while moving their head can benefit from using it.

What can I use a cardioid microphone for?

Using a cardioid microphone is a no brainer when you are to record vocals. This is because it virtually records everything that is pointed or talked into it, and ignores almost everything else. So, it is an obvious choice for voice recording. But that’s not the only application where it excels, the following are good applications where it excels too;

  • On stage

Cardioid polar pattern microphones excel when they are used on stage. When sound comes from all over the stage, a cardioid microphone is ideal for maintaining isolation and also preventing feedback.

  • Drum kits

Of course, technically, a drum kit is “a single instrument”, but then, it consists of a large number of various parts or individual instruments, all very close to each other. Isolation may seem impossible, although it can be done. With well-selected cardioid microphones and some creative positioning, you will be amazed at the level of separation you can achieve, even before you apply any kind of gate.

  • Untreated rooms

Cardioid microphones also do well in rooms with poor acoustics. These microphones can do wonders to minimize the effects of room reflections.

Pros of cardioid microphones

  • The microphone pattern is highly directional
  • Good sound rejection ability, up to -25dB, from directly behind the mic. 
  • There are also some sound rejections, for those coming from the side of the microphone
  • Excellent response from a wide sound pickup angle provided it is in front of the microphone.
  • Less responsive to room noise

Cons of cardioid microphones

  • Proximity effect
    • One of the biggest cons of the cardioid microphones is the proximity effect, a unique phenomenon that is exclusive to cardioid microphones. The proximity effect increases low frequencies when they’re positioned very close to the source to be captured. For example, an “inexperienced singer” may not be able to keep a constant distance from the microphone during recording, and this would cause the recorded sound to fluctuate (high and low, depending on how near or far the singer is to the microphone at a certain point in time during the recording). So, you see how this can cause problems.
  • Off-axis coloring
    • For most cardioid microphones, sensitivity to high frequencies decreases as the sound moves further off-axis. This, in turn, could hurt the recording result if an “inexperienced singer” (as in the example above) does not apply caution during unconscious head movements.

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