What are a microphone’s polar patterns?

by Ashish Barje · 10/11/2020 read

In any microphone product literature, you must have come across the term “Polar Pattern” or “Pickup Pattern” several times. Words like Cardioid, Omnidirectional, figure of Eight are mentioned with it… What is the meaning of these terms? Do you need to pay attention to them while choosing a microphone? Let me explain.

Microphone polar pattern tells us how sensitive that microphone is for sounds coming from different directions. It shows how well this microphone listens to sounds coming from its front, back or sides.

The most common microphone polar patterns are Omnidirectional, Cardioid & Figure of Eight.

OMNIDIRECTIONAL

Omnidirectional microphone listens to or picks up sounds coming from all directions equally. No matter which direction the sound is coming from, its output remains the same. Omnidirectional polar pattern is shown in the figure below. Let’s try to read & understand this graph.

You can see that the above graph has zero to 360 degrees mentioned. It represents all the directions around the microphonem where Zero (0) degree represents front of the microphone & 180 degrees represent the back of the microphone.

Now imagine a level meter showing this microphone’s output. The graph below shows how the level would be if the sound is coming from zero (0) degrees i.e. from the front of the microphone.

Now, if we do the same to all the other directions like say 90, 180 & 270 degrees, the graph would look something like this shown below.

The level meter is showing same output despite the direction of the sound source. That means the microphone is going to respond in the same way, no matter from which direction the sound is coming from. If one looks at this response in three dimension (3D) the graph will look like a sphere as seen under.

So in a nutshell, when you speak into an omnidirectional microphone, it will pick up your sound equally no matter in which direction the microphone is facing.

Omnidirectional Applications:
In any situation that requires the audience to hear sounds from multiple directions.Examples:
Rode Mics Lavelier, Sennheiser MD42, AKG C417 PP

CARDIOID

The second most commonly used polar pattern is Cardioid. The graph for the same looks like the one seen below.

The shape of this graph looks like a heart (upside down J) & hence is referred to as Cardioid. Now in this graph above you can see that the microphone gives us less output in 90 & 270 degrees compared to the one at zero degrees. 90 & 270 degrees are left & right sides of the microphone respectively, and 180 degrees is the backside of the cardioid microphone. When we look at this graph with level meters shown below, we can see it gives almost zero output for sounds coming from the back of the microphone.

This type of microphone is also known as Uni Directional microphone. The three dimensional representation of this pattern would look like the one shown in the image below.

We would use this pattern when we do not want ambient sounds to be picked up by a microphone. Cardioid microphones help reduce the feedback. When you want to use this type of microphone on stage with the foldback monitors, the best position for the monitor would be exactly in front of the singer/artist. Because that is the direction where the microphone is the least sensitive.

Cardioid Applications:
Where sound needs to be picked up from the front and sides, but not the rear. Ideal for vocals and speech.Examples:
Lewit LCT 440 Pure, Shure SM 7B / SM58, AKG D112 mk2, AKG P120

There are two more variations of cardioid polar pattern known as Supercardioid & Hypercardioid. The Supercardioid polar pattern looks like this.

Here one can see, although this pattern is slightly tighter in the front & can better reject sounds coming from its sides, such a mic does respond to sounds coming from its back side as well.

That means the sounds originating from the back of the microphone will be picked up by it too. So when one is using Supercardioid microphone, the stage monitors should not be in front of the singer/artist, but should be kept on the sides at an angle.

Supercardioid Applications:
Usually the best choice for filmmakers and movie creators to record in noisy environments.Examples:
Rode NTG5, AKG D5

FIGURE-8

The third popular polar pattern is Figure of Eight also known as Bi-Directional. As the name suggests, the polar pattern looks like the number “8”.

This type of pattern has maximum output on zero & 180 degrees i.e. front & back of the microphone, and the least output on the sides (90 & 270 degrees).

That means we can speak into this microphone in both front & back & it will give us equal output. But when the sound comes from sides, there will be maximum rejection. In three dimension (3D), this polar pattern looks like the one shown below.

A Figure-8 pattern microphone is used in recording studios as well as while using Stereo Miking techniques. These are best suited for recording podcasts as well, where two individuals can talk freely facing each other, and the microphone is placed in between the two speakers & reduces ambient noise pickup too.

Figure-8 Applications:
Recording 2 voices at the same time, or used while recording in stereo.Examples:
sE X1R, AKG CK94

There are several high end microphones that give you multi-polar patterns built into the same unit. For example: Lewitt LCT 640 TS, AKG C414 XLS. So, your setting of the pattern on such mics will need to be adjusted based on the type of recording being done. Using the right polar patterns on mics during a recording or a performance is critical to the sounds being captured.

I hope this article in simple language with the help of explanatory images, gets you to understand microphone polar patterns better. Knowledge of polar patterns will also help you make the right choice of microphones when you purchase them, and also use them.
You can also watch my video below where this concept has been explained in Hindi.