What is a Noise Gate and How to Use One

One of the keys to a clean mix is eliminating unwanted noise. When you add up all of the electrical, ambient, room, and other noises which can be picked up from microphones or your audio interface, this can be a time consuming task. A noise gate is an fast and efficient way to filter out unwanted noise on certain tracks, so let’s define what is a noise gate and how you can use it to keep your mix clean.

What is a Noise Gate

what is a noise gate

As I touched on in my audio effects tutorial, a noise gate is a relatively simple plugin which utilizes a threshold to filter out sound.

Unlike a compressor threshold which ignores any signal BELOW the threshold you set (depending on your compressor knee, of course), a noise gate exclusively targets and removes everything which doesn’t meet/is below the threshold.

Set the threshold at -20dB, and everything below that -20dB gets filtered out on that track.

Some of the more practical applications for a noise gate include removing room noise and breaths from vocals, or filtering out noise bleed in drum kit.

Speaking of practical applications, let’s talk about how to actually use a noise gate now.

How to Use a Noise Gate

You can use a noise gate in your vocal chain. Place it early on (pre-compression) to remove all of the noise you don’t want on the track so that you don’t have to worry about said noise affecting the compressor.

I actually went into more depth in my tutorial on the best noise gate settings for vocals.

To set the threshold, find the quietest part of the vocal itself on the entire track. Set the threshold roughly 3dB or so below this point to ensure that the gate doesn’t activate on and remove any of the actual vocal.

This should keep the breaths intact, as well. While you CAN use a gate to filter out the VOCAL BREATHS on your track, you’d be better served manually addressing them or using a specific plugin like the DeBreath from Izotope RX to specifically target and soften them.

The goal with breaths is never to remove them completely as this sounds unnatural so, similar to vocal sibilance, you simply want to attenuate it so that it’s still there but not as prevalent on the track.

Gating Drums

I mentioned another common application for a noise gate is with drums.

When close miking your kick, toms, snare, or even hi hat, you typically want to filter out as much of that bleed as possible.

This gives you a cleaner sounding drum kit and leaves the room sounds to microphones which are specifically used to pick up the entire room, not to mention it helps to minimize phase issues.

In this case, you want to again set the threshold on the noise gate to a few dB beneath the quietest instance of that drum hit. Of course you also need to make sure it’s higher than the loudest bleed from any other instruments.

In Ableton Live, I’ve got their “Gated Drums” preset shown on their stock noise gate:

gated drums

I’ve got this set on my snare, and as you can see above, there’s not a ton of dynamic difference between my snare and my kick (the darker peaks shown).

The key really is finding that sweet spot for the threshold between what you want to include and everything else. Sometimes you may need to automate the threshold in a section or two if there’s an uncharacteristic and rare swelling of bleed from other pieces of the kit during a fill (for example).

There’s a fair amount of “Hold” here which works well alongside the 30ms of release in reducing a snapping effect of cutting off any tail.

Of course you’ll likely be supplementing your snare with some light snare reverb to give your snare more of a tail and sustained decay, but that’s beside the point.

So if you’ve got a noise gate on your snare drum, set it 3dB below the quietest drum roll or hit to ensure that none of that instance will be affected.

With close microphones, noise gates work especially well because what you’re miking is so much louder than any bleed you get.

This lets you keep your close microphones relatively dry in terms of bleed to keep the drum mix clean.

That’s the basic way to use noise gates. We can also use their sidechain functionality to let in sound at choice times based on the behavior of another track.

One classic practical example is in my sine wave kick drum trick. Here we’re supplementing the fundamental frequencies of a kick drum which is lacking in them, or that 60-80Hz region, with an oscillator made sine wave.

The sine wave simulates the natural thickness of a kick drum and works well in a poorly recorded or thinner sounding kick drum.

With a noise gate on a constantly playing sine wave track, we sidechain that noise gate to our actual kick so that it only opens and consequently plays that 60-80Hz tone to mimic/supplement the kick fundamental when our actual kick plays.

Noise gates have a number of effective uses like that if you think outside the box, though they’re very effective for being a low effort way to simply clean up your track, as well.

Note that I mentioned in opening that noise gates are an efficient way to keep your tracks clean.

Technically the best thing you can do is manually trim your tracks when there’s not anything musical/wanted happening on them. Still, noise gates have their place in your mix, so use them to keep your mix as one of the many ways to avoid a muddy mix.

4 thoughts on “What is a Noise Gate and How to Use One”

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  3. Pingback: How to Gate Drums for a Clean, Professional Sound - Music Guy Mixing

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