Understanding technical audio vocabulary can be like trying to understand another language sometimes. But if you want to record the best audio possible, it’s important to get to grips with the jargon. When you’re starting out it, it’s easy to feel a bit lost; but there are so many resources available online -like my website- that it’s easy enough to get correctly informed. In this article, I’m going to talk all about the proximity effect, but what is the proximity effect and why does it matter? Let’s take a look.
The closer you move a microphone to a sound source, the more the lower frequencies increase in volume. Meaning the closer you get, the bigger the bass boost. This is the proximity effect phenomenon. Simple enough, right? You might be thinking ‘cool, more bass is good right?’. Well, yes and no. There can be both advantages and disadvantages to the proximity effect.
The Advantages of the Proximity Effect
One less commonly used benefit of the proximity effect, is you can actually use it to reduce the likelihood of feedback occurring. By putting a performer close to a microphone, yes, you’ll boost their low frequencies, but at the same time you’ll help to mic to be less sensitive to any other low frequencies. You can then cut the low frequencies using an EQ to remove any undesirable bass boosts.
You can also use the proximity effect if you want something to sound bassier, or increase the low-end of a sound source. For bass heavy instruments like a kick drum, bass guitar, or upright bass, you can create a fat bottom end. This is really useful for genres music like hop-hop and metal, where having a tight, larger than life low-end is essential to the sound.
Or Maybe you want to beef up a singers’ voice, or create a deep sexy Barry White kind of vibe. Ok, well the proximity effect can’t work magic, but it can certainty get you some of the way there. Think of that typical radio broadcast type of voice, what makes it so appealing? Yes, a lot of the time they have a certain vocal tone and way of speaking, but it also helps that they’re sitting very close to the microphones in the studio.
If you have a microphone, try it. First start speaking or singing 10 inches from the mic, then gradually move closer and closer, until arriving at 2-3 inches away. You’ll see how the lower frequencies become much more prominent. What also happens to the sound though when you get too close? This where the proximity effect can cause issues.
The Disadvantages of the Proximity Effect
We’ve established that the closer you get, the more bass there is, but getting too close to a microphone can also create muddiness and boominess. That means the sound becomes unclear, cluttered, and lacks definition. This is particularly problematic with sound sources that already have a lot of lower frequency content below 200Hz. Acoustic guitars suffer a lot with muddiness when you place a microphone too close. A common rookie mistake to point a microphone right at the sound hold, resulting in an unusable boomy sound. I’m pretty sure I also did this when I started out. Over time you’ll learn how to position your microphones for the best results. It’s all about distance, angle, and the microphone type that you use during you recording sessions. The more you experiment, the better you’ll become.
The Proximity Effect and Polar Patterns
Microphones can pick up sound in different directions. For example, in front of them (cardioid), all around them (omni), or from the front and back at the same time (figure-of-eight). These are known as polar patterns. You can read my full guide to polar patterns if you’re unfamiliar with the topic. The proximity effect affects figure-of-eight microphones the most, closely followed by cardioid, but the proximity effect has no impact at all on omni microphones. It doesn’t matter how close you get to a microphone with an omni polar pattern, the bass will not increase. Why is that though?
There are two types of transducers: pressure transducers and pressure gradient transducers. The proximity effect only has an impact on pressure gradient transducers, which respond to sound pressure variables between the front and back of the microphone’s diaphragm. Omnidirectional microphones have pressure transducers, whereas cardioid microphones have a mixture of the two. Thus, the reason why the proximity effect influences cardioid mics and not omni mics.
This is handy to know then, because if you want to record a sound source close without increasing the bass, then go for an omni microphone. If you do want to make use of the proximity effect, pick a cardioid microphone, which are the most commonly used microphones for recording music. However, there are plenty of microphones on the market with switchable polar patterns -like the AKG 414 on the left- giving you lots of flexibility and versatility.
Use the Proximity Effect Wisely
Now you know what the proximity effect is, you can use it wisely. You can use it to your advantage to boost the low-end of bass dominant instruments for an extra oomph, or reduce feedback in a live setting. Plus, now that you’re aware of the issue that the proximity effect causes, you can avoid it by using the correct microphone type; or simply by not putting the microphone too close to the sound source, which would result in a muddy mess. Like anything within audio production, it’s important educate yourself about what issues can arise. That way you can avoid, solve, reduce, or even use them for your own your benefit, and the proximity effect is the perfect example of that. The key is to experiment, play, have fun, and get familiar with these kinds of phenomena, because they occur frequently when working with sound. So, if you want to make the best music possible, at least learn the basics.
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