Noise Reduction remnants.

In cases this got lost, I’m following this audiobook mastering document.

https://forum.audacityteam.org/t/audiobook-mastering-version-4/45908/1

If you already have everything, it’s just three tools listed under — Process:

After that, Effect > Noise Reduction 9, 6, 6.

Yes, from earlier, where you get the profile noise sample makes a big difference. The audiobook requirements I’ve seen want you to include some Room Tone (hold your breath and don’t move) in addition to the show. That’s a good place to get the Noise Reduction profile. Resist the urge to Generate Silence in those areas instead of using Room Tone. They don’t like your background popping up and down in volume.

Koz