The BT ExpanderGate GX622 from Nomad Factory is a fully variable expander/gate plug-in that helps to suppress noise in the audio signal. The gate/expander lowers (or cuts) the signal if the level becomes too low as determined by the gate threshold setting, providing the perception of a lowered noise floor.
Similar to a compressor, the attack and release controls determine how fast the gate opens and closes. A low- and a high-pass filter assist in helping the gate decide when to open via a sidechain circuit. A listen switch helps with fine tuning the filters to the desired settings.