What is a Noise Gate and how to use it?

So you're asking yourself what is a noise gate and how do I use a noise gate? In this post, I hope to explain to you what a noise gate is and how you use them to improve the quality of your audio recordings.

Contents show

What is a noise gate?

A noise gate is used to eliminate sounds below a given audio threshold level.

So in its most simple form, a noise gate allows audio to pass through only when it is above a set threshold level. As long as the audio level is above the threshold that you set, the gate is open. If the audio signal falls below the threshold no signal is allowed to pass through.

Every audio signal contains some noise. It can be unwanted noise generated by the electrics or unwanted noise from your recording environment. A gate can be used to remove the unwanted noise from your recordings.

Noise Gate Settings & Controls

Most noise gates have some common controls that you need to know about. These are:

Threshold,
Attack,
Release,
Hold, and
Range.

So let's take a look at what each of these controls does in a little more detail.

Threshold sets the level that the gate opens. If the audio level goes above the threshold all the signal will pass through. Typically we would set the threshold just above the noise level this allows any intended signal to pass through but will cut off as soon as the signal goes below that.

The Attack is the time that it takes for the gate to open. Typically you'll want to use a fairly quick attack time so that the gate will be open for the beginning of the note being played.

The Release is the time it takes for the gate to close after the audio signal goes below the threshold. With a short release time, the gate quickly cuts off longer notes. Longer release times allow the signal to fade out slowly after the signal drops below the threshold.

The Hold is the time between the signal dropping below the threshold but before the release time begins. This prevents the gate from closing in short periods of time between notes or between phrases when you are working with speech.

The Range is how much the audio signal is attenuated when the noise gate is closed. Often the signal can be completely cut off when the gate is closed but in other cases, the level is reduced but not completely cut off. The range sets how much the signal is reduced when the noise gate is closed.

How to use a Noise Gate?

Alright, so how do you use a noise gate? You can use a hardware noise gate but these days it's more common to use a plug-in in your music production software.

Here is how you set a noise gate:

1 Create the audio track and record what you want at a good average signal level. Try to aim for an average audio level of -12 dB which is what most recording engineers aim for.

2 Insert a noise gate plugin to that track. Most DAWs come with a noise gate as a stock plug-in.

3 Adjust the threshold level so that it cuts the audio when there is only noise present. If you set it too close to your recording level it might cut some of your intended audio signals.

4 Set the attack and release times - my recommendation is to start with a fast attack time around 20 millisecond and medium release time around 400 milliseconds then you can adjust these settings until you are satisfied with the result.

Uses for Noise Gates

Some common use cases for noise gates are:

1 Vocals - to get clean separation between words and phrases. Be careful when using it though so that you don't cut out all of the breath sounds because they add an important human quality to the recording.

2 Electric guitar - especially when using heavy distortion, you will get a lot of noise from the boosted levels. Also, you can use a noise gate to separate the chugs and palm mutes.

3 Acoustic instruments - when recording acoustic instruments often you will get unwanted room noise, you can use a noise gate to bring out just the sound of the instrument and remove the unwanted room noise.

4 Drums - the close proximity of drums to each other makes it hard for a mic that's focused right on the snare drum for example not to pick up the hi-hat right next to it. If you adjust the threshold of each gate on each drum microphone to let only the individual drum sounds through. Then you can cut down the bleed coming from other drums and you'll get a much more focused sound and a cleaner mix.

Things To Remember About Gates

Noise Gates Don't Work Miracles

A lot of people seem to think that putting a gate on a tom track is going to make the toms sound mega loud and perfect and completely remove all bleed. Guess what! It's not going to happen. The more aggressive you set your gate, the more screwed up things are going to sound generally. This is especially the case when you are dealing with transients such as drums. If the drummer didn't give you nice loud toms that, when solo'd, completely overpower the cymbal bleed in the mic, your drummer screwed up. It's as simple as that.

Use Noise Gates In Moderation

What I like to do is set the gate so that it will only reduce maybe 10dB. Then I can set the gate so that it doesn't totally ruin my toms, but removes the junk by 10dB. If you do this for 3 tom mics, you'd be amazed at how well it can improve a kit. Theoretically, you should be able to crank the tom mics 10dB louder and have the same level of bleed. If that doesn't do the trick, the drummer doesn't know what he is doing.

Be Careful With Hardware Noise Gates

If you've recorded for more than 3 seconds, you know that no one plays the same level during soundcheck as they when actually tracking. 99% play much louder, but I have seen a few guys actually play softer. Anyway, if you set your hardware noise gate improperly, more than likely your track will be ruined. It will cut off low volume stuff. Now if you have a kick-ass, soundproofed control room, you can probably get away with this. If you don't, DO NOT USE A HARDWARE GATE GOING INTO YOUR RECORDING unless you really know what you are doing.

Conclusion

So, in conclusion, I hope this helps answer your question about 'What is a noise gate' and also 'how to use a noise gate'.

I have one last thing to mention though. Just remember that you don't have to have the gate completely off underneath the threshold. By using the range you can still have a bit of audio coming through even when the gate is closed, this will give you a little more natural sound.

http://en.wikipedia.org/wiki/Noise_gate

An alternative option to using a Noise Gate is using Volume Automation. Find out more in this Volume Automation Guide post.