Words from the Glossary
This month we continue our exploration of terms from our glossary. This month we're going to look at pickup patterns.
Microphone Pickup Patterns
This month's terms: polar pattern, pickup pattern, omnidirectional, cardioid, supercardioid, hypercardioid, lobar (shotgun), bi-directional (figure-eight), unidirectional
Although they are often used interchangeably, the terms polar pattern and pickup pattern are similar, but not the same. A pickup pattern indicates the sensitivity of a microphone in various directions. A polar pattern is a little more specific indicating the level in decibels (db) at various frequencies (since microphone sensitivity varies with frequency). The difference between these terms is shown in the illustrations in this article, with the upper one being a polar pattern and the lower being a pickup pattern for the hypercardioid pattern. You may occasionally hear other terms used, such as polar response, directional pattern, or directivity response, but these are not used as often.
There are basically six microphone pickup patterns: (1) omnidirectional, (2) bi-directional, (3) cardioid, (4) supercardioid, (5) hypercardioid, and (6) lobar. These are illustrated at the top of the page.
A microphone with an omnidirectional pickup has equal sensitivity in all directions. (Omni means "all.") The strongest sounds are picked up in the front and back of a bi-directional microphone, whose pattern is also called a figure-8, because the pattern resembles the numeral 8. (See the pattern as illustrated above.) When someone mentions a directional microphone, they are usually referring to one with a cardioid pattern, but that is really not accurate because a microphone with any of the patterns other than an omni is directional. The cardioid pattern receives sound predominantly from one direction. The pattern is called cardioid because it is heart-shaped. It and the next three patterns are called unidirectional. Each is similar to the cardioid, but is increasingly more narrow in their frontal sensitivity. The lobar is the most directional pattern. It is used in what are called shotgun microphones, and the pattern is sometimes called a shotgun pattern.
Now why do we care about all this? Well, selection of the correct pickup pattern is almost as important as choosing the correct microphone. An omni microphone is used when you want to capture much of the ambience or room effects. When that is not the case, then a directional microphone can help isolate sounds from the room sounds or other musicians in the same room. Frequently a bi-directional microphone is used when recording a singer and her guitar. By aiming the front toward the singer and the nulls (the areas of lowest pickup) toward the guitar and doing the opposite with a second microphone, you can do a fairly good job of isolating the vocal and guitar. When you are recording a large vocal group such a a choir, you may want to use a shotgun microphone with its lobar pattern to help zoom in on the soloist. And these are just a few of the situations in which the choice of a pickup pattern is involved.