Microphone Polar Patterns: A Beginner’s Guide
We discuss the basics of polar patterns.
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Microphone Polar Patterns: A Beginner's Guide · Source: Galak76 / Gino's Premium Images / Alamy Stock Photo
Ever wondered why certain mics are suited for different applications? We discuss microphone polar patterns in the context of home recording.
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Microphones are easy enough to use in your home studio if you know a thing or two about how they work. You’ve probably encountered different types of mics, including condensers and dynamics, but why are some placed close to the sound source, whereas others can be used for ambient miking?
Microphone Polar Patterns
The answer lies in the various microphone polar patterns we find on different mics, so let’s explore these and see how it can help you make the best choices in your home studio.
What Are Microphone Polar Patterns?
When we talk about microphone polar patterns, we are describing the effective pickup area of a mic in three-dimensional space. The shape of a polar pattern is important, as it determines the microphone’s sensitivity to sound coming from different angles. When we look at a particular microphone, its polar pattern is often included in the specs and we can read it from a 360-degree diagram.
The diagram consists of concentric circles, each representing a 5 dB decrease in level as we move toward the center, where the microphone capsule is, with 0 degrees at the front end where the mic is most sensitive. When you explore the types of microphones available, you’ll find that some mics have fixed polar patterns while others allow you switch between a variety of patterns.
This makes it essential, both in studio and live sound environments, to have a gauge of the polar pattern of the mics you’re using as an engineer and even as a performer. Mic placement is a key aspect of recording and sound reinforcement, so your understanding of polar patterns will help you achieve better results.
Microphone Polar Patterns: Different Types of Patterns
Now, let’s take a closer look at some of the most common polar patterns that exist. Once you have a basic understanding of these you can make microphone choices with confidence in your home studio.
Microphone Polar Patterns: Cardioid
The most common type of polar pattern you’ll find when you look at the microphones available is known as Cardioid. As the name suggests, the pattern resembles a heart shape, which means that the mic’s sensitivity is strongest directly in front of the diaphragm, while it decreases on the sides, and is weakest at the back.
With these characteristics, cardioid mics are also referred to as directional mics because they tend to capture the sound source directly in front of the diaphragm rather than the surrounding ambient environment. For this reason, cardioid mics are used for close miking instruments like guitar amps and drums in studio and on stage and are the preferred choice for vocals.
Microphone Polar Patterns: Omnidirectional
Also known as ambient mics, omnidirectional microphones capture sound equally in any direction. In addition, the pattern also produces the flattest all round frequency response and the best low-end response. This means that if you have a great-sounding live-room, hall, or auditorium, an omnidirectional microphone will excel at capturing dynamic performances in the space.
Another characteristic of the omnidirectional pattern is the way high frequencies are picked up with more directionality. From 20 kHz around the sides of the capsule, there is a drop-off until 16 kHz where the pattern starts to resemble a figure of 8. Overall, the truthful nature of the omni pattern makes it impossible to use them in untreated rooms or unfavourable ambient spaces.
Microphone Polar Patterns: Figure-8
The figure-8 pattern picks up in equal effective spheres on either end of the diaphragm, with equal dips in sensitivity at 90 and 270 degree angles on the sides. For this reason, figure-8 patterns are often implemented in mid-side and Blumlein mic techniques for capturing instruments in different situations.
Because the figure-8 pattern offers excellent side rejection and poor low frequency response, it is great for isolating small groups of performers in live orchestra recordings where you may have limited input channels. Bear in mind that a figure-8 pattern makes the microphone vulnerable to handling noise and wind, so try to avoid situations where these may be a problem.
Microphone Polar Patterns: Choosing the Right Mic
Now that we understand some of the basic polar patterns, let’s see if we can put this knowledge to use. Besides field and on set recordings which are there own niches, the most common applications for different mics are in studio and live environments.
Microphone Polar Patterns: Home Recording
Due to the fact that most home studios are not acoustically treated, cardioid mics are generally the only ones you’ll need for recording. Even if your room has harsh reflections and intermitant sound interferance from the surrounding area, using a cardioid mic in close proximity to the sound source with a relatively low gain setting can produce some good results.
Dynamic mics offer even more localized than condensers, and some options like broadcast mics even have internal shields and filters to reduce the bass doubling experienced from the proximity effect with cardioid mics. If you are looking to use a condenser mic for home recording, go for the cardioid-only rather than the multi-pattern version, as the chances of actually using the figure-8 or omni modes are slim to none.
Microphone Polar Patterns: Live Sound
In live sound situations, the stage is usually in close proximity to the main PA system, which presents a major obstacle. This means that our primary focus with live sound sources is isolation rather than trying to capture ambience. Besides cardioid mics, we also use mics with a pattern known as hyper-cardioid on stage, particularly for lead vocals.
Hyper-cardioid provides a more narrow 110-degree pickup area than the cardioid pattern. Although this requires more careful mic technique, it allows the lead vocalist to move freely around the stage and avoid the chance of feedback or spill from the potentially chaotic live stage sound environment.
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