When you do get it all sorted, you can send us a raw recording test. We can see if the normal mastering techniques will work and evaluate any other problems.
https://www.kozco.com/tech/audacity/TestClip/Record_A_Clip.html
Note all we’re officially doing is technical testing. Everybody knows what the ACX limits and standards are and generally how to meet them. However, you still have to pass theater and reading quality. We can guess at that, but that’s totally up to their Human Quality Control.
One fairly common rejection is someone who absolutely passes ACX Check, but they got there by beating their voice up with a stick—extensive processing, stiff noise reduction, compression artifacts, etc. That’s so not going to pass. Their model is someone telling you a fascinating story at the table over cups of tea. Not listening to cellphone distortion.
One of the goals of Audacity Audiobook Mastering is to not be obvious what we did, but suddenly your voice passes.
If you’re way far along, you can send ACX a short test.
https://forum.audacityteam.org/t/how-to-send-a-test-to-acx/49588/1
It’s not unusual to get rejected because of the amount of “silence” (room tone) in your submission. There are strict rules about that, how much to put in and where. Room tone is used everywhere, very quiet, but natural room noises, not Audacity > Generate > Silence.
https://www.acx.com/help/acx-audio-submission-requirements/201456300
Koz