What is Proximity Effect?
Introduction
The microphone proximity effect is often used to create a pleasing sound, but at other times, it’s simply an unwanted result of how the microphone is placed. This effect can enhance the depth of a speaker’s voice, add extra thump to a kick drum, or make a bass amplifier sound even boomier.
However, it can also lead to muddiness and make the low-end frequencies too prominent in a microphone’s signal—even when that’s not what you want.
So, what exactly does this mean, and how can we use the microphone proximity effect to our advantage as performers and audio technicians? We’ll likely answer these questions in this article!
What is Proximity Effect?
The proximity effect is a bit of technical jargon you’ll often hear when people talk about speaking into microphones. You might notice its audible impact on podcasts, YouTube videos, and other streaming platforms.
It’s easy to demonstrate, but understanding exactly why it happens requires at least a basic grasp of physics. In simple terms, the proximity effect is an increase in the amount of low-frequency output that occurs as a directional microphone gets closer to the sound source—so close they’re almost touching.
Put another way: the closer the microphone is to the sound source, the more the bass is boosted! The proximity effect is a phenomenon where the low-frequency response increases as you move the mic nearer to what you’re recording. The closer you get, the bigger the bass boost.
This can sometimes create problems, but it also gives you ways to shape the sound. The proximity effect happens because of phase and amplitude differences in the sound waves reaching both sides of the microphone’s diaphragm. These differences are caused by the way sound travels through the air, depending on its frequency and how far it is from the source.
The Pros and Cons of the Proximity Effect
The proximity effect can also hurt speech clarity and make the low end sound muddy, especially when “fattened” vocals and guitars start to clash with the bass and kick drum. So, the proximity effect is both a helpful tool and a potential problem.
You should use it to make sounds big, rich, and appealing, but you also need to control it for the best overall balance and clarity. The proximity effect is most obvious in sounds with a lot of low-frequency content below 200 Hz. This makes it an important factor when recording male voices, especially deeper ones, but it’s much less of a concern for female voices.
The proximity effect is usually an issue when recording guitars (the low E string is about 80 Hz). Acoustic guitars, in particular, can sound very “boomy” if the mic is too close. However, for bass-heavy instruments like kick drums, bass guitars, or upright bass, the proximity effect can actually help you get those big, fat low frequencies.
Proximity Effect On Different Mic Patterns
The strength of the proximity effect depends on a microphone’s pickup pattern. It’s strongest in figure-8 microphones, and still quite strong—though a bit less so—in cardioid microphones.
Omnidirectional microphones, on the other hand, have no proximity effect at all. This is because there are two types of transducers: pressure transducers and pressure gradient transducers. The proximity effect only occurs in pressure gradient transducers, which respond to differences in sound pressure between the front and back of the diaphragm.
Most microphones are cardioid, which are essentially a 50:50 blend of pressure and pressure gradient transducers. The proximity effect appears with varying intensity depending on the microphone type (like pressure gradient microphones) and the polar pattern.
You won’t get any proximity effect with the omnidirectional pattern, but it’s most noticeable with the figure-8 pattern. The cardioid pattern is the most commonly used, and it also produces a fairly strong proximity effect.
Proximity Effect with Multi-Pattern Mics
This type of microphone—most often large-diaphragm condensers—is very common in the studio, but you’ll rarely see it used on stage. A well-known example is the Neumann U87, which is probably the most widely used studio microphone in the world.
Multi-pattern microphones can switch between very different pickup patterns by electrically blending the two sides of a dual-diaphragm capsule. Since both halves of the capsule have a cardioid pattern, some people believe that a multi-pattern mic will always have a strong proximity effect, no matter which pickup pattern you choose.
However, Neumann’s research shows this isn’t true. When it comes to proximity effect, multi-pattern microphones behave much like fixed-pattern, single-diaphragm microphones—whether they’re set to omni, cardioid, or figure-8. The strength of the proximity effect changes with the pickup pattern you select.
In practical terms, a multi-pattern microphone gives you some control over the proximity effect. For example, if you want more low-end from a thin-sounding voice, set your multi-pattern mic to figure-8 mode for a stronger proximity effect.
Is Proximity Effect a Good Thing?
Vocalists often enjoy the proximity effect because it can make their voices sound “bigger,” more intimate, or more dramatic when they get close to the microphone. In recording circles, this technique is commonly called “eating the mic.”
By changing how far they are from the microphone and their angle to the mic’s axis, singers and voice artists gain an extra tool to shape their vocal sound as part of their performance. When you understand how a mic’s frequency response shifts with distance and angle, you can use the proximity effect as an extension of your voice—almost like an instrument in itself.
This falls under a broader topic called microphone technique, which is something that separates professional vocalists from amateurs. You can improve your technique by spending time with your mic of choice and listening to yourself on studio headphones.
Don’t try this with loudspeakers, though, unless you like the sound of screaming feedback. For other acoustic sources you might need to record or amplify in a live setting—like drums, speaker cabinets, or other stationary instruments—you don’t need to worry about the mic and sound source moving in relation to each other. However, the proximity effect can still be a powerful tool for tone control or as a kind of equalizer for whatever sound you’re capturing.
When is the Proximity Effect Bad?
Dealing with constantly changing low-frequency boosts can undermine the carefully set levels of your microphone input. If you or your voice talent tend to move or sway while performing, achieving a consistent vocal sound can become a real challenge.
Consistent vocal input is crucial, especially if you plan to edit multiple takes together. The proximity effect can also reduce speech clarity or make the low end of your mix sound muddy and crowded—particularly if it impacts several tracks or instruments.
Getting closer to the mic may help you take advantage of the proximity effect, but it also dramatically increases the sound pressure level the mic receives. This can lead to input overload or even cause the microphone’s diaphragm to distort. Being too close can also make plosives (also known as “P-pops”) much more noticeable.
You can control the amount of proximity effect by changing the angle of the microphone in relation to the sound source. If you rotate a directional mic, such as a cardioid, to a 90° angle from the source, both its front and rear sound-entry ports will receive the same energy, regardless of the frequency or wave-front shape.
Turning a directional mic slightly away from the source will reduce the proximity effect. While this may also affect the mic’s overall sensitivity and tonal balance, the change is usually minor for a typical cardioid mic at angles up to 45°.
Conclusion
The proximity effect is a natural phenomenon that occurs with microphones using pressure gradient transducers. The closer your microphone is to the sound source, the more likely you are to notice an increase in bass frequencies.
Bi-directional and cardioid polar patterns are the most affected by this effect, while omnidirectional mics don’t experience the extra buildup of low-end. As with all audio situations, context matters, so it’s important to trust your ears and decide what works best for the sound source and the desired final result.
By simply being aware of the proximity effect and how it sounds, you’ll be able to recognize it and either use it to your advantage or avoid it altogether.
