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Building Blocks 22: Mic Technique 5

Mic Technique pt 5: Mic Pickup and Placement

In addition to methods of transduction and functional design, mics are designed with a variety of pickup styles.  This refers to how a mic reacts to incoming sound from different directions and distances.  Generally, mic pickup patterns are one of several standard patterns.

Omnidirectional mics pick up sound equally (well mostly equally) in all directions.  This can create problems with feedback (feedback will be discussed in the next article) since an omni mic can pick up a speaker more easily, but this is not always true.  Omnis tend to have a smoother frequency response and fewer peaks with which to create feedback.   They also tend to have better response to low frequencies and are less susceptible to breath or wind noise.

Cardioid mics have a pickup that looks heart shaped when graphed (hence the name) with the mic head at the center “point” of the heart.  This means that the mic picks up the best on the primary axis (straight on into the mic) while rejecting sound from the rear of the mic.  Sound hitting a cardioid mic from the sides is reduced but in a pattern that varies for different frequencies which results in a “coloration” of these sounds.  Cardioids can be used to diminish unwanted sounds, which can help with feedback control, but tend to be much rougher in their frequency response compared to an omni.  They also tend to be more sensitive to wind and breath noises.

A supercardioid mic is similar to the cardioid but even more directional.  It’s pickup is concentrated more on the primary axis further rejecting sounds off axis, but they generally are slightly more susceptible to sounds from the rear.  Their more focused directionality makes them a solid choice for microphones that need to pickup sounds from farther away.

The vast majority of mics perform better with closer proximity.  If you’ve seen a few folks use a handheld mic, you’ve probably noticed that someone who holds a mic closer to their mouth is quite louder than someone who holds a mic at chest level.  You may also have seen a singer move a mic farther from their mouth when they start to sing louder.  When they do this they are in fact using a mic’s pickup range to their advantage to normalize (even out) their dynamic range a little bit.

When setting up a mic on a stand (well, your mic is probably built into the stand) you should endeavor to set the mic up as close to you as possible and as far from your speakers as possible.  I’ll explain this more when I cover feedback in more detail, but this will not only allow for better mic pickup, but it will reduce feedback.  A mic on a stand should also be placed as centered on your voice as possible.  As you move your head around the mic’s pickup will be affected as the sound of your voice impacts the mic at different angles.  This will be (marginally) true of even omnis.

Headset mics have several advantages to stand mics.  They will be quite closer to your mouth and they move with your head.  These remove 2 of the biggest problems with a mic on a stand.  However, they will be more likely to pick up your breathing (and chewing) because of the proximity to your mouth.  A headset mic should be placed near the corner of your mouth for best pickup.  To check if you will create a lot of breathing noises, put a couple fingers in front of or where your mic is placed and then take a deep breath and exhale strongly.  If you feel breath on your fingers then your mic will pick up breathy noises.

Generally speaking, a headset will perform better for gaming. They will pickup other sounds (such as screaming kids and barking dogs) less because they are designed for much closer range.

If you’d like to read more on these subjects I recommend Sound Reinforcement Handbook by Gary Davis & Ralph Jones.  Much of the content here is covered in Chapter 10.3