How To Use An Audio Gate

A gate is not always necessary when it comes to editing podcasts, but knowing how to use one when the time comes can save you a lot of tedium. You’ll most likely use a gate when you’re halfway through your edit and you hear someone nose-breathing so loudly that it could make even Tony Soprano cringe. What a gate will do is effectively mute audio that dips below a specified threshold. This obviously only works if you have recorded each person on separate channels. Otherwise, you’re likely stuck with it and should make peace by telling yourself that it “adds a dimension of realism that’s lost on bigger podcasts” or something.

Gate vs Expander

Let’s start by looking at the difference between a gate and an expander. A gate versus an expander is much like what a limiter is to a compressor. A compressor pushes a signal that goes beyond a specified threshold down by a set ratio, while a limiter completely stops the signal passing a specified point. By comparison, an expander compresses sound that goes below a specified threshold, while a gate cuts off the signal below that threshold entirely. 

The image above is taken from the Pro Tools stock plugin Dyn3 Expander/Gate, which has 19 visible parameters. However, we’ll mostly only need to focus on what’s under the EXP/GATE section. 

Threshold

Starting at the bottom right we can see the threshold. This threshold is the point at which the gate will close if the signal goes below it. The levels on the left of the plugin shows the dB of the incoming signal. Don’t overlook this when trying to decipher where to start with the threshold. You’ll want to set this during a point on the clip where the person isn’t speaking at all because that’s the only time the gate should be closing if this is all done correctly. 

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Attack

In the interest of keeping the listener blissfully unaware of the magic of editing, we’ll need to set the attack. This is paramount because it’s the difference between a smooth transition and a glaring shift from no sound making its way to the desired volume of a person speaking. If you set a long attack time, such as 300 milliseconds (ms), then the gate will open much slower and you’ll be able to hear the audio coming back up to its set gain. A very short attack time, such as 10 microseconds, means that the gate will open instantaneously from a listening perspective. We’re dealing with podcasts here, and people are going from not talking to suddenly talking, so you will want to set the attack time to be very short, if not as short as possible. There’s no point in having a person’s voice slowly re-emerge. 

Hold and Release

It makes sense to look at the hold and release parameters together because they should be set in conjunction. In case it wasn’t obvious up to this point, a gate is like an actual gate that opens and closes. The hold parameter is a bit like when you see someone coming towards a door and you want to be polite, so you open the door and then hold it open for them. The question is how long do you hold it open? (Maybe you acted on knee jerk instinct and when you look now, the person is a lot further away than you thought. There’s a point where it goes beyond the acceptable amount of time to be holding a door open and you’re now entering oddball territory.) 

You stop holding and the door closes. The release is how fast that door will now close. If holding the door was just a simple lapse in judgement, then you will slowly release the door and it will close as such. If you overcorrect for your previous awkward actions then you might throw the door closed quickly so the person doesn’t have a chance to see your shame-ridden face.

You might be tempted to use very short hold and release times so that when a person is finished speaking the gate will close immediately, letting no more noise through until they start talking again. But this is rarely what you want when using a gate for a podcast. Because people speaking tend to pause briefly and think in between words, you need to make sure that the gate isn’t closing too fast or else it could become obvious that the audio is stopping and starting. There’s a very big difference between any amount of audible sound and none whatsoever. 

Range

The range parameter is controlling how closed the gate will be when it is fully closed. You likely don’t ever want this to be over -40 dB, and realistically you want to set it as low as possible. There’s no reason for any amount of noise to be making its way through a channel where a person isn’t speaking at all. 

Ratio

And this brings us on to the ratio. This is how gain reduction is applied to the signal when it falls below the threshold. For gating, the ratio should be set to 100:1. This means that after the signal goes below the threshold, its gain is reduced to 1/100th of what it was previously. Again, for podcast editing we’re really only interested in gating. Using a lower ratio would be more appropriate for an expander, which we don’t want. The audio in between a person speaking isn’t adding anything and so we want it effectively muted, not just made quieter.

Use your Ears!

Keep in mind that all of these things will probably need tweaking. People make all sorts of noises in the background while not talking which can still be picked up if they are loud enough. A practical solution is to just cut these out as you hear them and hope that they are few and far between. A gate is not a one size fits all solution for podcasts. Don’t compromise the quality of your audio in an effort to shoehorn it in just because it can save you from having to cut large chunks of nothing. Once again, your most reliable tool for audio editing are your ears!


At The Podcast Studios we work with companies, organisations, and individuals to help them tell their stories in audio form. If there is any part of your podcast journey that needs a professional touch, from start to finish, get in touch today by contacting us at [email protected] or visit our website at www.thepodcaststudios.ie

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