When Choosing A Polar Pattern, Think Carefully
What Is A Polar Pattern and How do You Choose One?
Choosing a polar pattern is easy when you understand what they are and how they work. The polar pattern or “pick up” pattern is the area around the microphone in which it is going to be most sensitive to sound.
In other words, the area where it will be most effective in picking up the audio signal from the sound source. There are three main polar patterns with a few variations to some of them.
All microphones will have one of them and some have multiple patterns to choose from.
This polar pattern is designed to pick up sound evenly around the microphone in all directions. Omni means everywhere or all. This is the kind of pattern that is found on small, handheld voice recorders and on laptops and computer monitors because they are designed to pick up everything in the room so that they don’t have to be close to the source. Although the microphones in these devices are often not of high quality, that in no way means that this polar pattern should be frowned upon.
Omni was the first polar pattern back in the days when the term for a microphone was a “pressure microphone” because it was manufactured to pick up pressure waves from the air created by the sound source.
The omnidirectional pattern is not subject to proximity effect and has a very smooth characteristic throughout its’ frequency range. The lower register is particularly pleasing compared to other polar patterns.
It is interesting to note that, with omni being the original pick up pattern and with all the advancements in technology over the years, it is still included as a choice on the most expensive microphones manufactured today. I believe the reason for that is because this pattern most closely represents the way we actually hear sound in the atmosphere of a space. The subsequent polar patterns were designed specifically to isolate particular sounds.
The bidirectional polar pattern is the next generation after the omni and is also know as a figure eight or figure-of-eight pattern because it actually uses two diaphragms, one on either side of the mic. The pattern actually looks look the number 8 with the capsule being in the center where the two loops cross. This was very handy in the early days of radio because you could record two people facing one another with the microphone between them and achieve excellent sound rejection from the sides of the mic. These were originally called “pressure gradient microphones” because of the alteration to the omnidirectional pattern.
You can use this pattern if you only have one input in your home studio and you need to record a dialogue, but you will only be recording to one track so make sure the voice talents don’t “step on” the lines of the other by speaking before the other is finished.
If you are recording a single voice, this pattern can give you a tighter range of pick up with more side rejection if you have very good sound proofing on the other side of the microphone.
There are a few different types of this “one direction” pattern which was created when a genius engineer decided to combine the omni and figure eight patterns together into one microphone. The result was a particular focus on sound in one direction. Actually, a better way to explain it would be to say that there was a particular rejection of sound as certain areas of the two polar patterns would cancel each other out, leaving a pickup pattern that resembles the shape of a heart. As such, the cardioid polar pattern was born.
This is probably the most commonly used pattern to date because it’s focus is directly on the sound right in front of the microphone, rejecting much of the surrounding ambient noise. If you ever wanted to experience rejection for your voice-over work, this is the type of rejection you should try to acquire.
This is the preferred design for voice work and most handheld microphones use a cardioid polar pattern. But if you use it incorrectly you will learn about proximity effect. You may also learn about being “off-axis” if you tend to move around while you read a script or sing. Simply meaning that if you step outside the pickup pattern, the audio will start to sound muddy as the mic is no longer able to identify the higher frequencies. The bidirectional and especially the following patterns are also subject to these problems.
Hyper-Cardioid And Super-Cardioid
These are further advancements in narrowing the pickup pattern where the heart shape is tighter and smaller with what appears to be the makings of an aneurysm at the back of the heart or the rear of the microphone.
There is no real purpose for that small area of pick up at the back, it just seems to be the result of trying to exaggerate the rejection area by altering the combination of omni and bidirectional patterns.They may also be found on large diaphragm mics as one of the polar options.
These patterns further exaggerated for use in television and film or video on shotgun mics because it allows the microphone to stay out of the picture by having a long, thin range to the area of pick up.
For voice or vocal work, using tight patterns like these can result in an unnatural sound because they practically suck all ambient noise out of the signal. That is fine for television and film work because engineers will artificially replace the ambience in the post-production process.
If you need to use such a tight pattern because your room may have too much noise in it, I would suggest recording a low level of room noise with a cardioid pattern or even an omni pattern and gently mix it in with the super-cardioid voice over for at least a little bit of ambience.
Are We Facing North?
As long as we are talking about the most sensitive part of the pickup pattern for a microphone, we should talk about where to address the mic. This may seem trivial but even professional engineers sometimes point it the wrong way!
Most dynamic microphones are easy to figure out which end to speak into, but most condenser mics and nearly all ribbon mics are side address microphones. That means you talk or sing into the side of the mic, and the side you address is the one with the name brand logo facing you. Many of them have the roll-off and attenuation pad on the back of the mic, not the front. If you are not sure, look for the logo. The only exception to this is if you choose to use the figure eight polar pattern, and then either side may be used.
You will get the most out of your microphone by choosing the right polar pattern for the particular project you have in front of you. And don’t be afraid to experiment, you might be surprised at how different one mic can sound by switching to another pattern.
Thanks for stopping by, and if you have any thoughts on the subject drop me a comment and let’s get talking.