Hi Steve.

This is meant for a start, you will need to work it out further for your demand …

Set the Threshold to a value just below the level of background noise you want to eliminate. For example, this might be -30 dB or -40 dB, depending on your signal. The Compressor is adjustable from -60 dB to 0 dB.

Set the Ratio to a very high value. This ensures that the signal is completely cut off when it falls below the threshold, which mimics the behavior of a gate. Adjustable from 1 to 10.

Choose a very short Attack Time (e.g., 0.1 ms). This ensures the signal is immediately cut off as soon as it drops below the threshold. Adjustable from 0 ms to 200 ms.

The Release Time should be kept relatively short, so the gate closes quickly after the signal drops below the threshold. Experiment with values between 100-200 ms. Adjustable from 100 ms to 999 ms.

Set the Make-up Gain to 0 dB, as you don't want to boost the signal. Adjustable from -30 to +30 dB.

From the TM FX Help, Current Function: the amplitude graphics give a precise overview of the level changes caused by the current settings of Compressor (and Expander). The white dot shows the level of the input signal and with this whether the signal is within the processing range or not. The small light blue lines in the level meter show the currently active gain reduction. Settings for these Dynamic Meters are found in the Preferences dialog (F2).

In the screenshot below, I used the following values to reduce mouse clicks in the background.
Therefore, I had to choose a quite high value for the threshold.

Threshold: -55 dB
Ratio: 10:1
Attack Time: 2 ms
Release Time: 100 ms
Make-up Gain: 0 dB

If your browser displays the picture above too tiny, then use the URL below to download the JPG file and
to view it in your preferred image viewer:

https://www.dropbox.com/scl/fi/qp93jzbn … z&dl=1

You're welcome :-)

BTW, the factory settings have a "smooth" and a "hard" noise gate. You can experiment with these, too.
The Hard noise gate uses a combination of compressor and expander.

https://www.dropbox.com/scl/fi/5zev0yuw … b&dl=1

How the compressor and expander work together

Expander: the expander works by reducing the level of signals that fall below a certain threshold rather than cutting them off completely. This results in a softer reduction of noise or lower-level sounds, creating a more natural sound compared to a hard gate.

Compressor: The compressor ensures that once the signal rises above the threshold, it is controlled or compressed. This helps maintain a smooth signal above the threshold while the expander cleans up the lower levels.

Together, these effects create a "Hard Noise Gate" that significantly reduces noise below a certain level while ensuring smooth processing of the signal above that level.

My variant of RME's hard noise gate

https://www.dropbox.com/scl/fi/uxjsvcdu … z&dl=1

Expander:
Threshold: -40 dB (just below noise level) (*)
Ratio: 5:1 (moderate reduction)
Attack Time: 5 ms (fast response)
Release Time: 670 ms (smooth fade out) (**)

(*) With the expander threshold you can nicely control the noise reduction.
(**) Experiment with release time, e.g. 200 ms quick fade.

Compressor:
Threshold: -20 dB (controls louder signals)
Ratio: 6:1 (strong compression)
[same for compressor and expander]
Attack Time: 5 ms (prevents over-compression of transients)
Release Time:  670 ms (smooth recovery)