This is a plug-in for audio noise reduction before or after applying other effects that may highly amplify noise like a distortion, compressor (sustainer, limiter) or a guitar amplifier at high gain. The main purpose is to cancel noise from a microphone or pickup of a music instrument like a guitar before sound processing rest. You hold your strings for a second or keep your microphone in silence, allowing the plug-in to study noise pattern, then you set filtering level.