It also obscures the ability to change parameters
A word about that. Audiobook Mastering Suite is absolute and not relational like many other Audacity tools. RMS Normalize was a game changer. I don’t care where your RMS is now, when I get done it will be in the middle of the ACX submission requirement. Full Stop. There are no fuzzy options.
Success depends on Audacity’s ability to “overload” without damaging sound. This is where the 32 bit-floating format comes in. It doesn’t matter where the performance sound peaks go after RMS Normalize because the following tool, Soft Limiter, will gently reduce them to -3.5dB or below, thus matching the ACX Peak requirement. Yes, I know the requirement is -3dB, I also know the conversion to MP3 has errors and nobody can hear 0.5dB.
You put the Low Rolloff for Speech filter (which is actually relational) ahead of the whole operation so none of the tools is fooled by wind noise, thunder, rumble or low pitched trash caused by bad USB microphones.
That’s what those three tools are doing behind the curtain.
Koz