ACX Check Plug-in

If ACX Check appears under Analyze, it should be ready to go. Select some audio and Analyze > ACX Check.

Fair warning, you can fake out ACX Check. It will respond to ultrasonic noise and rumble whether you can hear it or not. The noise part of the test needs at least 3/4 second of pure background noise to work right. No breathing, shuffling, gasping or other human noises.

If you don’t have enough clean background noise available, it will measure whatever it can find and fail noise big time.

Also note, ACX Check works best when used as part of the Audiobook Mastering Suite.

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

Koz