Sound quality is usually the first priority when choosing a microphone. However, people often neglect to consider a microphone's behavior and usability. Even the best microphone will sound terrible if it's used poorly, and for this reason, it's important for livestreamers, musicians, podcasters, and video callers to understand the basics of microphone polar patterns.

Polar Pattern Describes a Microphone's Directionality

A microphone's polar pattern (also called a pickup pattern) describes its directionality. For example, a microphone with a cardioid pattern will focus on the space directly in front of its capsule, but it will attenuate (or reject) sound from its sides and rear. An omnidirectional mic, on the other hand, will almost indiscriminately capture audio from all directions.

The polar pattern used by a microphone will also affect its operating distance. When recording a voice, for example, an omnidirectional microphone needs to be held close to the speaker. Otherwise, the voice will sound unfocused and distant, and the microphone will capture too much background noise. Microphones with a more focused directionality can be held further from the speaker and achieve the same sound quality as the close-miked omnidirectional mic (which is why thin shotgun mics are usually kept at a good distance). But if you stick a directional mic too close to an audio source, you may encounter the proximity effect—bass frequencies will be boosted, often in unnatural-sounding ways (but sometimes in a pleasant way).

Gaining a basic knowledge of polar patterns will help you choose the ideal microphone for any application. It may also help you rectify problems in your current audio setup, such as unwanted noise or proximity effect. However, a polar pattern can only tell you so much. It does not describe how a microphone actually sounds, and it doesn't tell you the microphone's sensitivity, which can be the determining factor for placement or usability in some environments (for what it's worth, condenser mics tend to be way more sensitive than dynamic or ribbon mics, which is why condensers are rarely used at concerts or other amplified events).

How to Read a Polar Pattern Diagram

To help visualize polar patterns, we usually use a 360-degree plot point diagram. It looks intimidating, but it's simple; imagine a microphone capsule in the center of the circular diagram, with the front of the capsule facing the top (0 degrees) and the rear of the mic facing the bottom (180 degrees). The polar pattern chart for a cardioid microphone is shown below—notice the inverse heart shape, which tapers at the sides and tucks away at the rear.

You'll also notice a series of rings in these polar pattern diagrams. Each ring corresponds to 5 dB of volume reduction; looking at the cardioid chart, you'll notice that the polar pattern's sensitivity dramatically reduces around the halfway (90-degree) mark, which is exactly what you'd expect. This measurement helps us determine microphone placement and angle. Generally speaking, you shouldn't capture an audio source outside of a mic's "angle of acceptance," which is the point at which we see 3 dB of reduction. (This doesn't mean that you need to stay completely on-axis all the time. In fact, approaching a directional mic at a slight angle will reduce proximity effect, plosives, and sibilance—a handy trick when close-miking a speaker or instrument.)

Some polar pattern diagrams go the extra mile by including frequency response information (as differently-colored shapes—check the second slide above). This is due to the fact that frequency (or pitch) may affect the directionality of a microphone. A cardioid microphone may behave with less directionality when capturing bass frequencies, for example. (For a microphone's overall frequency response without any directionality data, check the actual frequency response graph provided by the manufacturer.)

Note that microphone polar patterns are typically tested in a soundproofed room or anechoic chamber. In real-world environments, microphones will pick up off-axis sound that bounces off of walls and other surfaces. If you find that a microphone is picking up unexpected noise, try setting it in a different position. Use your ears to determine when a microphone placement sounds good or bad.

Common Polar Patterns and Their Function

Even a shallow understanding of polar patterns can help you improve your recording quality. So, let's do a basic overview of five common polar patterns and their function. We'll also include polar pattern charts to help illustrate microphone directionality. At the very least, you can use this information as a cheat sheet when buying or selecting microphones.

Bear in mind that every microphone is unique. Two microphones with the same polar pattern may sound and behave in different ways. Polar pattern is just one of many factors that determine a microphone's quality and usability.

Omnidirectional

Omnidirectional microphones capture audio from all directions without any noticeable reduction in loudness. They do not suffer from the proximity effect, and they're good at handling sibilance and plosives, so they're very useful when close-miking a voice or instrument.

An omnidirectional microphone may come in any shape, size, or construction—condenser, dynamic, handheld, lavaliere, and so on. That said, very few large-diaphragm condensers use an omni pattern, and ribbon microphones are naturally bidirectional.

You can use an omnidirectional mic in nearly any situation. They're great for on-the-street interviews, amplifying a fidgety speaker, capturing the sound of a room, or recording multiple people at once. Of course, omni mics are useful in a studio setting. You can get very creative by experimenting with the placement and distance of an omnidirectional mic, but you may be limited to close-miking in a noisy or untreated room.

Omnidirectional microphones are used as the basis of the "distance factor." This measurement, which is often overlooked, tells us that an omni mic and directional mic will produce similar results when placed at different distances from a subject. Omni mics have a distance factor of "1," meaning that they can be substituted by a cardioid microphone at a greater recording distance.

Cardioid

Cardioid microphones focus on whatever's in front of their capsule. Sound that hits the side of a cardioid microphone will be attenuated, while sound that hits the rear will be almost completely rejected. Because cardioid mics are directional, they're sensitive to plosives, sibilance, and the proximity effect (bass frequencies are boosted when close-miking). Using a cardioid microphone at a slight angle can reduce the impact of these issues, though you may end up with a thinner sound.

Some people assume that only handheld mics are cardioid, but cardioid mics are come in all shapes and sizes. If you're looking for a microphone that can fit in any situation, cardioid is usually your best option. This polar pattern is popular in both live and studio environments, as it can capture sound with minimal background noise or amplify a subject without creating feedback (though this requires good mic placement). The world's most popular microphones—Shure's SM57 and SM58—use a dynamic cardioid design.

The cardioid polar pattern has a distance factor of "1.7," meaning that it can be placed 1.7 times the recording distance of an omni mic and achieve a similar sound. So, if you have an omnidirectional mic placed 3 feet from a subject, you can substitute it with a cardioid mic at a recording distance of 5.1 feet.

Bidirectional (Figure-8)

A bidirectional microphone captures sound from the front and rear of its capsule, but it attenuates sound from its sides. Traditional ribbon microphones use a bidirectional pickup pattern, and condenser mics with multiple patterns usually have a figure-8 option. Some radio hosts take advantage of the bidirectional pattern's extreme proximity effect to achieve the deep, classic "radio voice." This extreme proximity effect can also take the edge off of harsh instruments or other subjects.

Decades ago, bidirectional mics were the standard choice when recording a duet or a choir (done by placing people at opposite sides of the microphone), and they're still a common choice in two-person interviews or podcasts. You can also get very creative with the bidirectional polar pattern. If you're a guitar player, for example, you might use a bidirectional mic to record both your voice and your instrument (by pointing one side of the mic "up" at your mouth and the other side "down" at your guitar).

Like cardioid microphones, bidirectional mics have a distance factor of "1.7," so they may be placed 1.7 times the recording distance of an omni mic and achieve a similar sound. Note that the rear of a bidirectional microphone can pick up room noise, which may limit usability in some environments.

Hypercardioid

The hypercardoid polar pattern is highly directional. It rejects most of the sound from its sides, but it picks up a small amount of sound from the rear. When positioned properly, hypercardioid mics are excellent at isolating a single audio source, even in noisy settings.

But, because hypercardioid mics have such a narrow "angle of acceptance," they require precise placement and shouldn't be used on moving subjects (unless you are also moving the microphone). The increased directionality of this polar pattern can produce an extreme proximity effect.

Hypercardioid microphones are often used for live amplification, as they reject off-axis sound that can create feedback or muddiness. They're also handy when recording or amplifying a voice in a noisy room. Many shotgun mics use the hypercardioid polar pattern, but shotgun mics use an interference tube to achieve an even tighter "angle of acceptance." Shotgun and hypercardioid mics aren't interchangeable.

Because of its extreme directionality, the hypercardioid polar pattern has a distance factor of "2." You can place it two times the distance of an omnidirectional mic and achieve a similar sound. If you place an omni mic 3 feet away from a speaker, for example, it can be substituted by a hypercardioid mic at a distance of 6 feet.

Supercardioid

Supercardioid is a less extreme version of the hypercardioid pattern. It picks up a bit more sound from the side, but less sound from the rear. For this reason, supercardioid and hypercardioid mics are often used interchangeably, though the supercardioid pattern is a bit more forgiving to moving subjects or poor mic placement. This polar pattern exhibits the proximity effect, of course.

You'll find supercardioid microphones on stage and in studios. It's also a popular option among podcasters, who often record themselves in untreated or noisy rooms.

The supercardioid polar pattern has a distance factor of "1.9," meaning that it can be placed at 1.9 times the distance of an omni mic and produce a similar sound.

How Did These Polar Patterns Come to Be?

In the early days of recording, we only had omnidirectional and bidirectional microphones. Omnidirectional mics work by measuring sound pressure at one point of space, which is why they lack any directionality. But bidirectional mics measure the difference in pressure between their front and rear. This is done using two elements at opposite polarities—the electric current at the front of the mic moves at a positive polarity, while the rear is negative. These differing polarities cancel each other out when they intersect at the sides of the mic, hence the "figure-8" pickup pattern of bidirectional microphones.

We get the cardioid pattern by combining an omnidirectional and bidirectional signal—cardioid rejects sound from the rear because the bidirectional pattern's negative polarity (at the rear) is canceled out by the omnidirectional pattern's fully positive polarity. Other polar patterns were discovered using similar logic.

More recently, multi-pattern microphones have taken hold. Multi-pattern microphones like the Blue Yeti use two cardioid capsules in a back-to-back configuration. By selectively turning these capsules on and off, or by reversing the polarity of one capsule, a microphone can achieve several polar patterns. Other multi-pattern microphones, like the Lauten Audio LA-120, simply have swappable capsules.

It might seem a little overwhelming at first, but by taking the time to study microphone patterns you can select the right microphone for your needs and get optimal audio quality as a result.