This is where I warn you that ACX Check can be fooled. It needs at least 3/4 second of clean room tone (background sound) to measure Noise. In general, a straight narrative reading doesn’t have silences quite long enough to work. Give it a second (or longer) of dead quiet before you start presenting.
Freeze and don’t move. The tool can hear your pants moving.
This is one method of AudioBook Mastering.
https://forum.audacityteam.org/t/audiobook-mastering-version-4/45908/1
Let us know if you have troubles.
Koz