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Learn Music and Audio Production | iZotope Tips and Tutorials

Everything You Need to Know About Noise Gates

by Arthur Kody, iZotope Contributor August 26, 2021
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What exactly is a noise gate and how can you use it effectively in audio production? In this article, we’ll cover what a noise gate is, typical uses for them, and how to set up a noise gate in iZotope’s Nectar Pro and Neutron Pro.

In this piece you’ll learn:

Pro Tip: If you don’t already have these plug-ins, you can get access to them by subscribing to Music Production Suite Pro

What is a noise gate?

A noise gate is an audio processor that works to eliminate sounds below a given threshold in a recording. Noise gates are similar to compressors in that they both reduce the volume of audio. However, compressors work on audio signals that pass over the given threshold, whereas noise gates reduce signals that are under the given threshold.

Noise gates work very similar to how a fence gate would. When you set the volume threshold of a noise gate, the gate will “open” if an audio signal passes the threshold, allowing the audio to come through the gate. The gate will “close” whenever the audio ducks below the threshold, diminishing the amount of the signal that is allowed to come through.

The amount of volume reduction a noise gate performs on your audio is dependent on the ratio you set. The higher the ratio, the more the gate will apply volume reduction to your signal once it passes below the threshold. The rate at which the gate opens can be modified by the “attack” control and the rate at which it closes can be modified by the “release” control. Some noise gates like the one in Neutron Pro also offer a “hold” control which allows you to set the time it takes to begin closing the gate after your signal dips below the threshold.

How are noise gates used in mixing audio?

Removing unwanted background noise

Noise gates can be very useful for removing unwanted background noise from your recordings. You can add a noise gate to an electric guitar to help cut down the amount of amplifier buzz during the gaps between notes played. When applied to a vocal, they can help tame the breathiness and cut out any room reverb or ambient noise from between phrases.

Here’s an example of using a noise gate on some rather breathy vocals:

Vocal Example without Noise Gate

Vocal Example with Noise Gate

Hear how adding the noise gate removed the breaths? That’s because the audio signal of the breaths alone wasn’t at a high enough volume to go over the threshold I had set in my noise gate. Applying gates to remove noise pollution in your audio can save tons of time making volume automation adjustments.

Trimming transients

Since noise gates can be used to shape the volume dynamics of a recording, you can use them to trim any transients that may fall below your set threshold. For example, one of my favorite uses for a noise gate is to simplify and strip down my drum loops. Take a listen:

Drum Sample without Noise Gate

I love the tonal quality of the kick and snare, but I don’t care for the sound and rhythm of the hi-hats. So, I applied a noise gate with a threshold that falls just above the volume of the hi-hats. Since the kick and snare both go over the threshold I’ve set, the noise gate cuts out only the hats. This leaves the kick and snare untouched, which simplifies the drum loop. Check it out:

Drum Sample with Noise Gate

Sculpting your sound

The drum example above was fairly simple and straightforward because the sound I wanted to cut (the hi-hats) fell below the threshold I had set, and the initial hit of the kick and snare did not. What if we applied this same concept to a piano? Using a noise gate with a quick attack and release can make for a more punchy sound. Check it out in action:

Piano Sample without Noise Gate

Piano Sample with Noise Gate

For more clever ideas on how a noise gate can be used, read this article about creative uses for noise gates in music production.

How to set up a noise gate in Nectar Pro

If you’re wanting to add a noise gate to a vocal, using Nectar Pro is the way to go. First, add the Nectar Pro plugin to your track, click the “plus” icon next to the Pitch module, and select “Gate” from the dropdown menu.

How to add a noise gate in Nectar Pro

Now, press play in your DAW. You’ll see a real-time graph of your audio which will be very useful in determining where you should set your threshold. 

Press play to see your waveform in the Nectar Pro noise gate

Click and drag the “Open” slider to set your threshold. Dragging the “Close” slider lower than the Open threshold will activate what’s called Hysteresis, meaning that if your audio signal goes above your set threshold, the gate will open. But, the gate will only close if it dips below the amount you set for the Close slider.

Adjust the threshold settings in your noise gate

Now, play with your Attack and Release settings to dial in the sound you’re needing for your vocal.

How to set up a noise gate in Neutron Pro

If you need to add a noise gate to an instrument track, Neutron Pro has you covered. First, load Neutron Pro onto your instrument track, click the plus icon at the top left of the window, then choose “Gate” from the dropdown menu.

How to add a noise gate in Neutron Pro

Now, adjust your threshold with the Open and Close sliders. Play with the Attack, Release, and Ratio settings to get the effect you’re needing. Typically, faster attack times work better for noise gates, otherwise it can produce somewhat of a pulsing sound as each note starts. But, feel free to get experimental with it. Neutron Pro also includes an additional option for “Hold”. The Hold amount determines how long the gate will remain open after your signal goes below your threshold before it begins closing.

Adjust your settings in Neutron’s noise gate

Neutron Pro also allows for multiband noise gating so you can have different gate settings for different frequency ranges. To activate this feature, click the plus icon toward the top of the Gate window and then drag the slider to set the frequency crossover point. Now you will be able to apply different processing to different parts of the frequency spectrum. This is especially useful if you want to target certain frequency ranges to remove only low rumble or high hissing sounds. This gate can also sidechain sources, opening up sound design possibilities. Check out this article on sidechain compression and how to use it for more information.

How to use multiband noise gating in Neutron Pro

Start using noise gates 

Noise gates are very useful tools for removing unwanted noise and shaping the overall dynamics of your recordings. Hopefully you now have a good understanding of how noise gates work and how to go about using them to enhance your audio productions. With their intuitive interfaces, Nectar Pro and Neutron Pro really make working with noise gates simple and efficient. If you haven’t already, start a free trial of Music Production Suite Pro. It includes full access to Nectar Pro, Neutron Pro, and dozens of other tools to help bring your productions to the next level.

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