Polar patterns of microphones are a representation of a microphone’s sensitivity to the sound relative to the angle or direction from which it receives the sound. In simpler words, a polar pattern decides how well the microphone will hear the sound from various directions. This is known as the directionality of a microphone, and different microphones have different polar patterns depending on the application.
The challenge for sound engineers is to select the right polar pattern microphone for a given application and use the proper technique to capture the desired sound and reject any unwanted noise or feedback. Omnidirectional, unidirectional and bidirectional are the three top types.
Omnidirectional microphones, as the name suggests, are equally sensitive to sounds arriving from all angles or directions. Due to this, there’s no need to aim omnidirectional microphones in a particular direction. This is useful when you’re using a lapel microphone to capture the speaker’s voice so that the individual can easily move their head without affecting the sound. Omnidirectional microphones have their advantages in some situations, but they are less than ideal in several other situations.
They can’t be aimed away from any undesired sources, which can lead to unavoidable background noise and feedback. Furthermore, omnidirectional microphones lack directionality and can’t be used to monitor on-stage feedback, rejecting room ambiance or background noise. However, the speaker or the source can be moved around without it affecting the sound.
Omnidirectional microphones have the benefit of sounding natural and open as compared to the unidirectional and bidirectional alternatives. This attribute makes omnidirectional microphones a good choice to be used in studio environments where acoustics are good or in live performances where the stage volume level is low. They are mainly used when capturing a wide source of sound such as a choir or recording in a studio.
Cardioid microphones are a type of unidirectional microphones and are designed to be extremely sensitive to all sounds entering at the front and least sensitive to the sounds at the back. This unidirectional pickup of sound means that cardioid microphones are ideal for efficient isolation of unwanted ambient noise. It also offers high resistance to feedback, especially when compared to the omnidirectional alternatives.
Cardioid microphones are the essential microphones for live performance and the most commonly used unidirectional polar pattern microphone. They also have a wide pickup area on-axis and the rejection is maximum at 180 degrees off-axis. Cardioid microphones reduce the ambient noise by two/thirds compared to their omnidirectional counterparts.
Cardioid microphones are especially useful if the stage monitors are to be placed directly behind the source. The very first single-element cardioid microphone in the world was developed by Ben Bauer in 1937. In the past, these microphones used to mix the omnidirectional element with the bidirectional pattern pickup element so that the output could be mixed in equal parts electrically and yield a cardioid pattern. These microphones are used commonly in studio recording when the acoustic environment is less than ideal or for live performances.
Subcardioid, also referred to as wide cardioid, is an obscure polar pattern. The directionality of subcardioid microphones resembles omnidirectional microphones but not entirely. Its gives an open and natural sound, which is suitable for performances with low stage volume when the sound desired is more organic.
The subcardioid polar pattern is much more resistant to the proximity effect, especially when combined with dual diaphragm elements. However, a drawback associated with subcardioid polar patterns is that they are much more susceptible to feedback.
Their best application is small acoustic and low-volume gigs. The minimal reduction in the sensitivity from the back given by a subcardioid microphone is enough to control feedback but only at a low-volume gig. Using a subcardioid microphone at a low-volume gig gives you the benefit of natural tone and almost zero proximity effect that comes with a less directional microphone.
Subcardioid polar patterns are often combined with other patterns such as hypercardioid to develop a versatile microphone. Hypercardioid is ideal for loud stage environments, while the subcardioid is perfect for quiet conditions. It takes on the form of a studio quality microphone as well due to its lower stage volume and reduced feedback risk.
Hypercardioid microphone is like an even more sophisticated and directional version of the supercardioid. Its front pickup angle is not only narrower than the cardioid, but it’s also more confined than the supercardioid. At 105 degrees, hypercardioid microphones beat the 115-degree front pickup angle of the supercardioid. It’s least sensitive at 110 degrees and not at the rear or 180 degrees off-axis. This results in an even greater rejection of the ambient sound and feedback.
The same rule applies to the hypercardioid that it needs to be placed properly when being used onstage with wedge monitors. Putting the wedges directly behind the microphone won’t do the trick as the monitors need to be placed on either side of the microphone at their least sensitive angle.
A drawback is that hypercardioid, while more directional than the supercardioid, is also more sensitive to the sound from behind than the supercardioid. Even the front and side pickup are tighter due to a narrower front pickup angle, so it’s important to be careful with the microphone placement as even the smallest movements while using a hypercardioid microphone can affect its performance.
This increased directionality is useful for very loud stage environments where unwanted sound can bleed back into the microphone.
Supercardioid microphone offers a much narrower pickup as compared to that of cardioids and due to its super directional design, the ambient noise rejection is greater as compared to cardioid and omnidirectional microphones. However, supercardioid microphones also pick up a small amount of sound directly from the rear and due to this reason, the monitor speakers should always be placed to the side that is facing the dead spots.
Supercardioids are suited to loud stage environments due to the fact that their directionality gives high gain before feedback. The front pickup angle is much narrower than a cardioid microphone with a precise value of 115 degrees. Cardioids are least sensitive at 180 degrees off-axis, but supercardioids are least sensitive at 125 degrees.
Supercardioids offer a much more focused pickup than cardioids, but they have to be placed correctly. What this means is that when on stage, the wedge monitors should not be placed directly behind the microphone but on either side of the mic at their least sensitive angles. This will give not only a more focused pickup but also a better rejection of ambient noise and feedback.
This is the third main type of polar patterns after omnidirectional and unidirectional. A bidirectional mic features the figure-of-eight polar pattern (ribbon-shaped pattern) which, as the name suggests, picks up sound from the front and rear only.
This unique polar pattern rejects all sounds from the sides i.e. at 90 degrees and only receives sound from the front and back of the microphone. These bidirectional microphones that feature a figure-of-eight polar pattern are usually ribbon microphones or large diaphragm condenser microphones.
Their unique design leads to bidirectional microphones having two distinct angles of maximum sensitivity as well as two distinct angles of minimum sensitivity. As far as their sound is concerned, it resembles the sound of omnidirectional microphones a lot and they deliver a natural and open sound.
The pickup angle or coverage is only 90 degrees on both the front and the rear. In terms of ambient noise pickup, they have the same amount of pickup as cardioids. Their application is also highly focused and unique, and they are typically used in cases where it’s required to pick up two opposing sources of sound such as in a vocal duet.
Understanding the different microphone polar patterns is all about understanding that the comparison between the polar patterns is only in terms of their application and properties. One polar pattern is not better than the other, generally speaking. However, for particular applications, different polar patterns are more ideally suited.
All the polar patterns briefly discussed find their applications somewhere, but even despite their properties, these patterns require consistent performance across multiple frequencies. This means that a great microphone, regardless of its polar pattern, will perform consistently across the complete frequency spectrum. That’s why polar patterns are used to specify applications but not the quality or performance of the microphone.
Interested to know which microphones are the best regardless of its pattern? Check out our Top 10 Recording Microphone list.