An expander with a fixed "infinite" downward expansion ratio. Used extensively for controlling unwanted noise, such as preventing "open" microphones and "hot" instrument pick-ups from introducing extraneous sounds into the system. When the incoming audio signal drops below the user set-point (the threshold point) the expander prevents any further output by reducing the gain to "zero." The actual gain reduction is typically on the order of -80 dB, thus once audio falls below the threshold, effectively the output level becomes the residual noise of the gate. Common terminology refers to the gate "opening" and "closing." Another popular application uses noise gates to enhance musical instrument sounds, especially percussion instruments. Judicious setting of a noise gate's attack (turn-on) and release (turn-off) times adds "punch," or "tightens" the percussive sound, making it more pronounced.