noise-gate

A noise gate or simply gate is an electronic device or software that is used to control the volume of an audio signal. Comparable to a limiter, which attenuates signals above a threshold, such as loud attacks from the start of musical notes, noise gates attenuate signals that register below the threshold. However, noise gates attenuate signals by a fixed amount, known as the range. In its simplest form, a noise gate allows a main signal to pass through only when it is above a set threshold: the gate is open. If the signal falls below the threshold, no signal is allowed to pass : the gate is closed. A noise gate is used when the level of the signal is above the level of the unwanted noise. The threshold is set above the level of the noise, and so when there is no main signal, the gate is closed.