Whenever you look at the specifications or features of a microphone, there is always a row called directionality or polar pattern of a microphone which has a graph and a name like Cardioid, Omnidirectional, Bidirectional, and Multi Pattern. You must have thought what is directionality or polar pattern of a microphone? And how does polar pattern or directionality of a microphone affects a microphone’s performance or my choice for a microphone?
In this blog post, I’m going to answer these questions regarding the polar pattern of a microphone along with some other necessary details which you should know before purchasing a microphone.
DIRECTIONALITY or POLAR PATTERN OF MICROPHONES
Directionality is the sensitivity of a microphone to sound advancing from various angles or directions. In simpler terms, directionality of a microphone defines angles or directions from which it accept sound.
You might have noticed it many times, when a singer performs on the stage, there is rarely any background noise as the microphone picks sound from the front of diaphragm and not from front or sides.
In a podcast, voice of both the speakers is ‘bright’ though they are speaking into the same microphone from opposite direction.
Due to number of different applications of a microphone, there are different direction patterns available which are plotted on a graphs know as polar patterns.
Before looking the polar pattern, keep in mind that the graph you see is in 2D which looks like a circle but in practical applications (3D) it looks like a sphere.
WHAT DOES A POLAR PATTERN REPRESENT?
The polar pattern of a microphone represents how it sensitive to sound coming from various direction (0 degree to 360 degree) to its present placement (It is assumed that microphone is placed at 0 degree).
As you can see in the graph, the assumed microphone takes most of the sound from the front, taking very less sound from the sides and almost no sound from the back side. Later in the post, you’ll see that this type of directionality of a microphone is called cardioid polar pattern.
According to the plot of sensitivity of a microphones on graph there are various types of polar pattern, few of which are very common and widely used like cardioid polar pattern which takes the lion’s share in number of microphones. Let us understand three major types of polar patterns or directionalities along with their modified versions:
Cardioid Polar Pattern (Directionality)
Most of the popular condenser microphones use cardioid polar pattern directly or indirectly (most of multi polar pattern condenser microphones also have cardioid polar pattern along with the other options).
Microphones with cardioid polar pattern are most sensitive in the front and as we move to the sides and bottom it becomes less sensitive, which when plotted on graph makes a heart shape and this heart shape gives it its name Cardioid polar pattern.
Ben Bauer, a Shure engineer was the driving force behind the world’s first single-element cardioid design when he began developing the first Shure Unidyne in early 1937 as stated on one of the Shure blogs.
It is considered to be a reliable partner in both live and studio conditions.
In a live performance, the spotlight is on the performer or the instrument in front of the microphone which helps in making the sound ‘bright’ and keeps background noise away.
In a studio, cardioid condenser microphone are ultimate king in recording vocals and instruments in isolation. If you want to record acoustic guitar, acoustic piano, drums or any other instrument with great nuances, cardioid microphones should be your first choice.
In case of a cardioid microphone, you’ll also have to consider proximity effect. In simplest terms, proximity effect is an increase in bass or low frequency response when a sound origin or source is close to a directional or cardioid microphone as defined on Wikipedia.
There are four version of a cardioid microphone namely hyper cardioid, super cardioid, shot gun and sub cardioid. Let me briefly introduce each one of them to you.
In case of super-cardioid microphone, the front sensitive area narrows down and sensitivity at the rear side increases.
In hyper-cardioid microphone, the front sensitive area becomes narrower than that of super cardioid microphone and the sensitivity at the rear of the microphone gets broader.
The difference between a sub-cardioid and a cardioid microphone lies in the fact that it is not a cardioid microphone nor an omnidirectional (I’ll tell you about it after few paragraphs) microphone, but somewhere between them to record sound from sources which are in front of microphone and are also in motion.
Best Cardioid Condenser Microphones
There are bunch of amazing cardioid condenser microphones available in the market among which Rode NT1-A (IND|UK|US), MXL 990 (IND|UK|US), Audio-Technica AT2020USB+ (IND|UK|US), Behringer B-1 (IND|UK|US) are few to name which are used by audio professionals.
Shotgun is the extreme case of a cardioid microphone which eliminates all sounds from side and pickup sound mostly from the front even if there is significant distance between the source and microphone. Most of the shotgun microphone looks like large capsule. It is used in places where the microphone can’t be placed near to the sound source like recording roar of a lion in wildlife documentary with a video camera.
Best Shotgun Microphones
Bidirectional Polar or Figure 8 Polar Pattern
Bidirectional is polar pattern or directionality in which the condenser microphone picks sounds from two sides (front and back) and rejects sound from other two sides which can be great when recording an interview, duet vocal or drum overhead. Other than this they are great in recording natural voice but are not a great choice for stage performance.
When this directionality is plotted on the graph, it forms a shape similar to figure of 8 which give its second name Figure of Eight Polar Pattern.
Best Figure 8 Condenser Microphones
One of the world’s largest microphone manufactures MXL’s R150 (IND|UK|US) can be a striking choice for figure 8 microphone as it uses an aluminium ribbon transducer to produce a bidirectional pick up pattern. It is also one of the best figure 8 only microphone.
As the name suggests, microphones with omnidirectional directionality picks sound equally from all angles and directions to give a natural look to the sound.
There are some factors which affect the directionality of an omnidirectional microphone.
Proximity of the sound source is one of them which affects its frequency response.
As mentioned on Audio-Technica blog, ‘physical size of the microphone has a direct bearing on how well the microphone maintain its omnidirectional characteristics at very high frequencies’.
They are great in recording ambiance or open sound along with wide sound source like an orchestra or choir.
Best Omnidirectional Condenser Microphones
The Audio-Technica ATR-4697 ATR Omnidirectional Condenser Microphone (IND|UK|US) can be a great omnidirectional microphone choice. The light weight, Tascam DR-05 (IND|UK|US), a USB condenser recording device also excels in the job.
Multi Pattern or Switchable Polar Patterns
If your planned purpose uses combination of above mentioned polar patterns then don’t worry, you’ll not be required to purchase two microphones. Some condenser microphones are available in market which have multi-pattern or switchable setup and you can change the polar pattern according to your need.
Multi pattern microphones are quite expensive compared to other polar pattern microphones but are worth the price due to their versatility.
Best Multipattern Condenser Microphones
The Rode NT2A (IND|UK|US), a large diaphragm microphone is an excellent choice if you want to purchase a multi pattern microphone as it gives you choice to select from directional (cardioid), omnidirectional and bidirectional (figure of eight) polar patterns.
In the END
A microphone can have three major types of directionality which suits in different purposes like a cardioid microphone performs better than others on live stage while omnidirectional microphones are amazing in recording ambience and bidirectional microphones are great in recording interviews.
None of them is superior to other but all of them performs distinctly in different conditions. There are also some microphones which gives the performer a choice to change the pattern according to their need.