Mic Patterns 101

The AKG C414 is a multi-pattern mic that can be switched to any of five polar patterns.

The AKG C414 is a multi-pattern mic that can be switched to any of five polar patterns.

Microphones are an essential part of every sound system, and learning to understand and use their various sonic characteristics is a must for any audio tech—whether you work in a studio or in a live environment. This info is important for singers and instrumentalists as well. Regardless of your job, understanding the inner workings of the mics you use will allow you to take full advantage of their potential and give you the best sound possible with a minimum of side effects like feedback, uneven response, unwanted tone variations, or unpredictable results from day to day.

Not all mics are created equal; mic manufacturers design their products for different jobs and to respond differently to the sounds around them. One of the most important elements in this is a microphone’s pickup pattern. The pickup pattern influences how a mic “hears” the sounds it’s pointed at and how it rejects or ignores sounds that it’s not directly pointed at. Unlike our ears, which can be “focused” by our brains to listen only to, say, the piano or the lead vocalist, a microphones “hears” everything. In some applications, that’s exactly what you want. But other times, you want a microphone to pick up only certain sounds. Pickup pattern can be used for this.

So what pickup patterns are available and how do you make sense of those graphics that you see when shopping for microphones or selecting from your mic vault?

There are three basic mic patterns available: omni-directional (also referred to as simply “omni”), cardioid, and bi-directional (also referred to as “figure-8”). In addition to the big three types, there are also the cardioid variants hyper-cardioid and super-cardioid.

Omni-Directional Mics

An omni mic picks up audio from all directions equally.

An omni mic picks up audio from all directions equally.

An omni mic is designed with a pickup that hears equally from all angles. With an omni, you can get the same level singing directly in front of the mic as from the sides (as long as you sing at the same distance from the mic). That also means that the mic will pick up sound coming from the rear of the mic body just as well as it will pick up sound coming from what the user perceives as “the front.” Many lavalier mics are omni-directional so that the speaker’s voice is picked up equally as he or she moves relative to the mic’s axis.

Use an omni pattern mic when you want to capture the main sound source plus the sound of its surroundings. In other words, an omni mic picks up more ambient sound and that might be exactly what you need for a particular application.  Another advantage to the omni pattern mic is that it does not exhibit the phenomenon called the “proximity effect” whereby sounds that are within a few inches of the mic get a bass boost. (For more on the proximity effect, see the section on the cardioid pattern mic.) The omni mic is like our ears with absolutely no brain “focusing.”

Cardioid Patterns

A cardioid mic has a strong front-facing pickup pattern with a strong rear-side null point.

A cardioid mic has a strong front-facing pickup pattern with a strong rear-side null point.

The basic cardioid mic pattern gets its name from the pattern’s visual similarity to a heart.

A cardioid mic is the most common mic pattern in use today. It has a strong front-facing (on axis) pickup pattern and a large null point 180 degrees from the front, making it an excellent choice for applications such as hand-held vocals, guitar speakers, drums, and horns. The rear null point means that a cardioid mic rejects sounds coming from behind it, which in turn is an advantage in live sound applications. A cardioid mic can be used close to a stage wedge before feedback occurs (where an omni would be a disaster), and it offers more separation between the different sound sources on stage when multiple mics are being used, allowing the engineer to mix each mic with more isolation.

All cardioid mics have the proximity effect built-in; the closer you bring the mic to the sound source, the more low frequency boost you get. This can be both an advantage and a disadvantage, so it’s important that engineers and musicians alike understand how the mic behaves. Guitar speakers sound great with a cardioid mic right up on the grille cloth, thin sounding vocalists get a bit more body to their vocal sound when they “eat” the mic, drums are punchy and “in your face” when the mic is just a few inches from the drum head.

The very-familiar Shure SM58 mic has a standard cardioid pattern.

Cardioid Variations

One thing to be aware of when shopping for a new cardioid pattern mic is its polar response diagram; all cardioid mics are not created equal. As mentioned previously, there are two cardioid pattern variations, hyper-cardioid and super-cardioid, also available.

Super-cardioid has a similarly strong front pickup pattern with a small rear pickup pattern.

Super-cardioid has a strong front pickup pattern with a small rear pickup pattern.

A hyper-cardioid pattern will pick up sounds from directly behind the mic in addition to the front.

A hyper-cardioid pattern will pick up sounds from directly behind the mic in addition to the front.

The super-cardioid pattern exhibits a tight on-axis response very similar to the standard cardioid but with a small rear-facing node that will allow a bit more of the surrounding ambient sounds to be captured by the mic.On the other hand, the hyper-cardioid pattern has a much larger rear node. Another way of thinking of the hyper-cardioid pattern is that it’s like an omni response with two null points at 45 degree angles in the rear. This mic pattern will pick up substantially more ambient sound.

This may not be the best choice for a singer who stands in front of an open wedge speaker. Why? Look at where the rear-facing node is: right where the wedge speaker would normally be. That means that a mic with this pattern would, under these circumstances, be prone to feeding back much sooner than a standard cardioid pattern mic. But if you move that wedge speaker left or right at a 45-degree angle to the mic, you can take advantage of the response pattern to diminish the likelihood of feedback if all other factors are equal: the sound from the speaker would now be pointed at the mic’s null point.

The Figure-8 Pattern

A figure-8 mic pattern uses two capsule facing in opposite directions.

A figure-8 mic pattern uses two cardioid capsules facing in opposite directions.

The bi-directional figure-8 mic pattern actually consists of a pair of cardioid capsules set back-to-back. As we saw earlier, a cardioid pattern has a strong front-facing pickup and a large null point to its rear. Placing a pair of these pickup patterns in the same housing produces a strong pickup at the front and rear, with null points on each side of the mic.

Ribbon mics are typically figure-8 pickup patterns, and this particular configuration has been growing more and more popular the last few years thanks in part to companies like Royer Labs. Check out a recorded example.

A figure-8 mic paired with a cardioid mic can be used to capture a very realistic stereo image. This particular application is referred to as “mid-side” recording and does require a bit of processing to flip the phase of one side of the figure -8 mic’s output to create the stereo image, but it can produce excellent results.

Bottom Line

Keep an eye on your mics’ pickup patterns, and make sure you’re always working with the pickup pattern and not against it. And if you’re unsatisfied with the performance of a given mic, take a moment to check its pickup pattern as part of your troubleshooting.

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  1. Cierra T. says:

    I love this! Finally a break down that’s not super nerdy and actually easy to understand.

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