Do you know that this is a very important tool in the audio recording world? As an aspiring audio engineer or music producer, merely understanding its various parameters and controls is just not enough. You need to learn more about how this device (or software) is applied in the audio industry. Hence, the vital question for today is – How to use a Noise Gate?
Today in this article, we will go through the various applications of the noise gate. Understand the recording processes that this audio tool is often involved in. Find out how the noise gate is used not only for technical audio engineering purposes, but also for creative output. Are you ready to continue learning? Of course you are! Then, let’s go!
The topics we will be covering today are:
- Sound isolation
- Creative applications
- Live Sound
You will often see noise gates being employed during multi-track recording sessions. They have the primary function of minimising sound leakage from other sources into a microphone, other than the one the microphone was intended for. One prevalent example would be the miking up of a drum-kit.
It is common practice during multi-mic drum recordings, to have one microphone positioned to capture the snare drum sound and another to capture the kick drum sound. The signal produced by the snare’s mic, will consist of a louder snare signal, together with a softer kick drum signal (as a result of the kick drum, being further away from the snare’s microphone).
Here is where the noise gate comes into play. If the noise gate’s threshold level is set accurately, the snare drum’s signal can be isolated (no more soft kick drum signal). However, the release rate has to be very quick, in order to fully isolate the snare drum signal. This often results in the tail end of the snare sound to be ‘chopped off’.
Often times, this “chopped off” effect is not desirable in conventional multi-track productions. Hence, this issue is usually remedied by incorporating one or more (typically two) overhead microphones. The overheads are used to record the drum’s overall sound, thus acting as a general “audio glue” for all the other gated sources.
Noise gates are also utilised during a live recording’s editing process, as audio engineers find it very effective in removing background noise that is typically present between passages or pieces of dialogue. Engineers must often be very careful when setting the gates, as it should not be triggered by spurious noises such as when people are moving chairs.
There are instances where an optical microphone switch is used for vocal applications on stage. If somebody is standing closely in front of the microphone, an infra-red sensor will be triggered and the microphone will be switched on.
Noise gates can be creatively used in music production. An example would be the “time-controlled” noise gating used on Phil Collins hit single “In the Air Tonight”. The well-known “gated reverb” effect heard on the drums, was created by Hugh Padgham (producer), in which the intense reverberation added to the drums does not decay naturally as it is cut off by the noise gate after a few milliseconds.
The same effect can be achieved by inserting a noise gate in between the path where the dry snare signal is sent to the reverb effects unit, and having the snare sound to be routed to the side chain of the gate unit. By setting the external side chain to be active on the gate unit, the gate will ‘cut off’ the dry snare signal when it has dropped below the threshold, and the reverb sound is left untouched.
Multi-latch gating is a technique invented by Jay Hodgson, and is very commonly used in classical music recordings for a long time. Producer Tony Visconti is often credited for using this technique on David Bowie’s “Heroes”. Bowie’s vocal performance was recorded in a large space, with three microphones placed 9 inches (23 cm), 20 feet (6.1 m), and 50 feet (15.2 m) away, respectively.
Each of the three microphones is applied with a different noise gate, so that the farther microphone was triggered only when Bowie reached the appropriate volume (due to the respective noise gate’s threshold setting), and each microphone was muted as the next one was triggered.
“Bowie’s performance thus grows in intensity precisely as ever more ambience infuses his delivery until, by the final verse, he has to shout just to be heard….The more Bowie shouts to be heard, in fact, the further back in the mix Visconti’s multi-latch system pushes his vocal tracks [dry audio being perceived as front and ambience pushing audio back in the mix]…” (quoted from Understanding Records by Jay Hodgson).
Originally called envelope following, trance gating became prevalent in trance music (hence the name trance). It involves a gate being applied on a track additional to the one it is affecting, producing an amplitude profile (in the additional track) that closely follows the first track. Envelope following is useful in tightening sloppy performances and to create syncopated rhythms.
An example would be a synth pad that is playing whole notes, but is simultaneously keyed to a guitar or percussion part. To have a better idea of this technique, check out DJ Nexus’s “Journey Into Trance” (1:11), Le Chic’s “Everybody Dance”, and Diana Ross’s “Upside Down”.
In live concerts, noise gates are central in the drum miking process, especially for heavy metal shows. Individual drum and cymbal microphone channels will usually have noise gates applied to them, so that the signal will only come through when the affected drum or cymbal is being played. This greatly minimises “bleeding” between the drum mics.
We have come to the end of this article. Did you guys learn something valuable today? Well, I hope that all of you will now be able to effectively use noise gates in your productions!
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