Noise Gate — attenuates signal below threshold.
Param layout: 0 = threshold (dB, -80 – 0) 1 = ratio (1:1 – inf:1, represented as 1.0 – 100.0) 2 = attack (ms, 0.1 – 100) 3 = release (ms, 10 – 2000) 4 = hold (ms, 0 – 500)