Simply put, a ‘noise gate‘ is a type of hardware device or plugin that can mute and un-mute a signal during an audio track when a particular instrument is not being played, or resumes playing. It is used to eliminate leakage from a signal.
Unwanted leakage can be referred to as ‘noise’. It is crucial to note that noise gates don’t actually remove any noise from a signal.
For e.g., consider a farmer who opens the gate to let his dogs through and closes it again to keep his sheep out. In terms of a noise gate, the main difference is that (unlike the farmer) you can set the gate to open and close automatically as needed. Additionally, you can control how long the ‘gate’ stays open and the speed at which it opens and shuts.
A noise gate can also be deliberately used to produce different results. Use it to open and close the sound of an instrument and create stuttering effects and more. Alternatively, it can be used to expand the dynamic range of a signal.
In its most simple form, it allows the signal to pass through only when it is above a set threshold: that’s when the gate is ‘open’. If the signal falls below the set threshold, no signal is allowed to pass (or the signal is substantially attenuated): and the gate is ‘closed’.
The most common parameters associated with a noise gate are as follows:
- Threshold – sets the level at which the gate opens to let sound through.
- Ratio – the balance between the original sound and the gated sound.
- Attack – sets the time it takes for the gate to open.
- Hold – allows the gate to be held in an open state after the signal level has fallen below the threshold.
- Release – sets how long it takes for the gate to go from fully open to fully closed. A fast release quickly cuts off the sound while a slower release is more like a fade out. Setting the sound to release too fast can induce a clicking sound, so be careful with this function.