If you are taking the Intro to Music Production course through coursera.org, please skip to the next paragraph. If you are not, here is a quick debriefing on what this blog post is all about : ) I enrolled in the aforementioned production course online (it’s free, by the way, so you might want to check it out for yourself) and part of the evaluation process involves us having to re-teach an element of the coursework. Since this information might be useful to other people, I thought I’d post these assignments on my blog. That being said, I am a student (not an expert), so don’t take what I say here as the ultimate truth. In fact, if you have other insights that might enhance or correct my understanding of the content, I’d love for you to leave a comment at the bottom of the post : )

Gating is an effective tool for automatically hiding (technically, the process doesn’t erase or remove) Noise between musical moments throughout an entire track, so that you don’t have to manually edit every single section – which saves a lot of time! Trust me. I’ve done it manually. Never again… never again…

It is particularly useful on quiet vocal tracks, where you may have the gain turned up higher or have the mic closer to the singer in order to capture the voice, but (naturally) simultaneously capture more acoustic noise (room noise, lip noises, breath sounds) and possibly electric noise (faulty cables, etc.) that you, the producer, or the artist did not envision as part of the recording. Some producers/artists won’t care and feel that whatever gets picked up is an authentic and integral part of that recording. For the sake of teaching this lesson, however, let’s say that the producer wants a really clean vocal track, with as little noise as possible, because they plan on using many vocal layers with lots of reverb and they want it to ring out as long as possible. Even though breath sounds are usually pretty quiet, when they cut in between words they will interfere with the natural decay of the sung word sound and this will likely clutter the audible space even more once you get all of the wet vocal layers playing at the same time.

Step 1:

Load up your session and record your vocal track. If it is one of many tracks, solo it so you can hear any breath noise clearly.

Step 2:

Listen carefully to the track and determine if gating is needed. If yes, enlarge the wave form and find the loudest breath. This will help to ensure that you do not apply more Gate than is necessary (which can potentially interfere with signal levels/sounds that you DO want to come through), but you’ll get enough to remove any other lower level noises.

Step 3:

Create a loop/cycle and press play so that breath section will repeat over and over while you tweak the gate settings.

Step 4:

Insert your gate. Depending on your DAW and plug-in library, you may find your gate controls are nested with compressors, downward expanders, and limiters all in the same full feature device. At present, I don’t have one of these devices, so this demonstration will be done with the default expander and gate plug in that came with Pro Tools LE 8.

NOTE: The following steps do not have to be done in this order, I have simply arranged them in an order that made sense to me. Also, basic gate devices will not have all of these options, so just follow along with the steps that apply to your plug-in.

Step 5:

Establish the Threshold. This is how the gate understands when it should open and close. Opposite to compressors, which attenuate signals above the threshold, gates attenuate signals below the threshold, so you’ll only hear signal that is of a higher decibel level than your threshold settings. Adjust the threshold knob slowly until you reach the point where you no longer hear the breath as it plays on repeat, but try not to go beyond that point. You want to keep the threshold as low as possible, so that it doesn’t interfere with any important sounds of higher amplitude.

Step 6:

Adjust the range. If you don’t want the gate to completely mute the output signal below the threshold, you can adjust the range setting so that it will only attenuate by a specific decibel amount, rather than to infinity. This can make the performance feel more natural (no complete silence) and can also make the attack time seem faster, because the gate has a shorter door to swing open (so to speak).

Step 7:

Adjust the ratio. This is the degree to which the input signal will be attenuated below the threshold and is expressed as a ratio of input : output (output is always 1). In the video example, I have chosen a ratio of 3.0 input to 1 output, meaning that for every 3 dB of input signal below the threshold, the gate will only output 1dB. This, in effect, tapers the input signal by thirds so that the lower the signal is, the more attenuated it will be.

Step 8:

Adjust the attack. This is how fast the gate opens, allowing desired signal (everything above the threshold) to come through. So, the smaller the attack time, the faster it opens -just like fades, the steeper the slope, the quicker the fade. Because we want the desired signals (such as words) to come through as quickly and clearly as possible, we’ll set the attack time quite low. If it’s too high, you’ll get a “swell” or noticeable “fade in” kind of effect, which can be used artistically, but is not desired in this particular case.

Step 9:

Adjust the hold. This is how long the gate will stay open after the signal returns below the threshold -in effect, delaying the release (next step), which can help you fine tune the attenuation to make it sound more natural, less robotic, and avoid “chattering” (which happens when an audio signal hovers around the threshold instead of continuing steadily past it).

Step 10:

Adjust the release. This is how fast the gate closes, preventing unwanted signal (everything below the threshold) from coming through. So, the smaller the release time, the quicker it closes. Because we want to make sure the gate closes before a desired signal level begins, we’ll keep the release quite low too.

Step 11:

Turn the look ahead function on, if desired. This is a signal delay that enables the gate envelope to take a look ahead and prepare for what noises are coming up, without affecting the currently playing signal.

Step 12:

Listen to the track and make sure the gate is a) reacting the way you want it to and b) only removing the noise you want and not interfering with any important sounds. If it the gate is being triggered in places you don’t want it to be, you might need to look into adjusting the EQ of the side chains (explained well here) or you might need to use your editing tools to remove a particular problematic breath and re-adjust your gate settings to hide the next loudest one, following the same steps.

Video Demonstration:

Youtube was being funny when I posted this, so if the video only plays audio, try watching here.

Ideally, it won’t take long to get the right settings and you’ll only have to make one or two cuts at the most. Alternatively, if the rest of the track sounds great and this particular breath is faint enough that you can only hear it by listening really closely, with the track soloed, you might make the executive decision to let it slide and get naturally buried in the mix.

Now what?

By inserting a gate first (before compressing and equalizing) you, in effect, sweep the dust off the floor of the track you want to polish later. Meaning, the compressor won’t heighten any wanted noise and you won’t have to fight with an EQ to filter out hissing when you want the high frequencies to shine. The manner in which you choose to polish said track relies on your vision and creativity. One school of thought is to EQ first then compress. Others feel it is better to compress and then equalize. Read more here.

Happy gating! :)

More advanced gate strategies and information:

Sound on Sound

Doctor Pro Audio

Wikipedia