Noise Gate

An audio effect called noise gate can be regarded as an expander with a slope of -∞. With this feature, the effect results in the total muting of the signal below the chosen Threshold. As already deduced from its name, the primary application of the noise gate effect refers to gating out the noise by setting the Threshold just above the background noise level. This further leads to the gate's opening only when the desired signal with the level above the Threshold is present. In order to explain this more clearly, we can say that a noise gate is used when the story of the "signal" is above the level of the "noise."  

Noise Gate Parameters

A typical noise gate effect possesses the following parameters that control the outcome: Threshold, attack, hold, decay, and range. Additionally, there might be high and low-frequency controls and an external sidechain option in more advanced units.  

Threshold

Is in charge of setting the level at which the gate will open.  

Release

They define the time the gate changes from open to fully closed. It is the fade-out duration. A fast release abruptly cuts off the sound, whereas a slower release smoothly attenuates the signal from open to closed, resulting in a slow fade-out. If the release time is too short, a click can be heard when the gate re-opens. The release is the second-most common control within a gate after Threshold.  

Attack

They define the time the gate takes to entirely change from closed to open. It is the fade-in duration.  

Hold

Used to define the length of time the gate will stay fully open after the signal falls below the Threshold and before the Release period is commenced. The hold control is often set to ensure the gate does not close during short pauses between words or sentences in a speech signal.

Range

They are used to set the amount of attenuation to be applied to the signal when the gate is closed. Often, there will be complete attenuation. This means that no signal will pass when the gate is closed. Complete attenuation is not desired in some circumstances, and the range can be changed.  

External Sidechain

Furthermore, an external sidechain option is available in more advanced types of noise gate effect units. This additional input allows the gate to be triggered by another audio signal. Furthermore, newer effects from the noise gate are "trance gate" or simply "the gate." In these effects, the noise gate is not controlled by an audio signal but by a preprogrammed pattern. This results in precisely controlled chopping of the sustained sound.