Understanding (and Using) the Proximity Effect in Audio Recording

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Like Don LaFontaine, the king of movie-trailer voiceover, some actors have naturally deep timbres that lend themselves to the epic scope of cinema. But for the rest of us, there are technical cheats that can boost bass in the voice to create a phenomenon known as the proximity effect. This isn’t just a fix that’s done in postproduction; it can also happen during production. Here’s everything you need to know.

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What is the proximity effect?

Proximity effect in microphones explained

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The proximity effect refers to the way that the low-end frequency on a microphone increases the closer it gets to the source of the sound—the closer to the mic, the greater the boost in the bass. 

As an actor, this quality can be useful when a scene calls for an earthy baritone. If you don’t have a deep voice, the proximity effect will create the illusion that you do. This can be used to convey qualities like gravitas, depth, intimacy, and strength.

What types of microphones can capture the proximity effect?

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Microphones come in a variety of shapes and sizes. For example, a mic used to record instrumentals for a film score or a musical recording won’t work for singers or voice actors. The point is to achieve the correct frequency so you capture the best version of the type of sound you’re recording. The proximity effect only occurs when using a directional microphone (a mic that only picks up sound from one direction). 

All microphones have a diaphragm—a thin membrane that reacts to external sound pressure (i.e., sound waves). This is what makes a microphone a transducer: a device that, like the human eardrum, converts sound waves into electricity. When it comes to the diaphragm of your microphone and the proximity effect, remember these two terms: 

  • A pressure microphone doesn’t create the proximity effect: Since this kind of mic only exposes the front side of the diaphragm, it records omnidirectional audio input—meaning that it will pick up sound waves from all directions and have equal gain (i.e., the amount of sound a mic picks up). 
  • A pressure-gradient microphone does create the proximity effect: This type of mic exposes two sides of the diaphragm, meaning they’re directional. It will only pick up sound waves from the spot where the mic is pointed. 

Whether or not a directional mic creates the proximity effect depends on the distance and frequency of the sound waves striking both sides of the diaphragm. This depends on a sound wave’s phase (location and/or timing) and amplitude (strength, which is measured in decibels).

The mic will only capture an earthy, baritone timbre if the frequency is low, meaning that there’s more pressure hitting the diaphragm than a higher-frequency sound—so the closer you are to the mic, the more pronounced the bass. Bear in mind that the sound will reach the back side of the diaphragm with a slight delay.

How to intentionally use the proximity effect

Woman recording voice

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How far away you stand from the mic is only one part of creating the effect; it’s equally important to consider the tone and volume of your voice. Speak a little softer and at a lower pitch than you ordinarily would. Since your mouth is closer to the mic than usual—and perhaps the only thing separating you from it is a pop filter, a shield that avoids the popping sounds caused by sharp exhales—speaking too loudly will negate the effect.

Think about the vocal delivery of LaFontaine or a stereotypical radio DJ. They don’t yell, screech, or whisper into the mic; their volume is measured, allowing the proximity effect to do the rest of the work.

When to avoid using the proximity effect

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If you’re looking to capture a more balanced, less bass-heavy vocal quality, the proximity effect isn’t the right choice. It can be difficult to nail this type of recording; the closer you are to the mic, the greater chance it will pick up “plosives”—the pronounced popping sound you risk creating when saying words that include P’s or B’s. It’s also harder to achieve the proximity effect if you’re a particularly animated performer. Movement causes fluctuations in amplitude, which will create an inconsistent recording.

Of course, the easiest way to avoid it is by using an omnidirectional microphone instead of a directional one. But if the latter is the only type available, be sure to stand farther away from the mic so less pressure hits the diaphragm.