The Greenlit Blog
Spec breakdowns, rejection post-mortems, and the stuff QC reviewers actually look at.
Most advice on "audiobook mastering" comes from people who've never had to sign off on a file before it ships to a retailer. This is the other side of that desk — notes from someone who has, on what actually trips up submissions and how to avoid it.
How to Remove Mouth Clicks From Audiobook Narration
Mouth clicks aren't a re-record problem. See how automated mouth de-click detection actually works, and how to check your file before ACX does.
July 14, 2026 · 6 min read
Downward Expander vs. Noise Gate for Audiobook Noise Floor
A gate slams silence shut; an expander turns it down gently. The real dBFS numbers, plugin settings, and why ACX rejects "clean" gated files anyway.
July 6, 2026 · 5 min read
Why ACX Rejects Files That Sound Fine
ACX rejections often have nothing to do with your performance. Here's why files that sound fine fail the spec — and how to check yours first.
June 27, 2026 · 6 min read
How to Fix Your ACX Noise Floor (Without Destroying Your Recording)
Failing ACX's noise floor spec? Here's how to measure it correctly, find the source, and fix it without wrecking your vocal performance.
June 27, 2026 · 6 min read
Coming soon
Noise floor, explained without the jargon
What −60 dB actually means and why your room is probably louder than you think.
The real cost of a $700 mastering pass
And when it’s worth it.
One chapter, nine checks
A walkthrough of every spec Greenlit measures and why each one exists.
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In the meantime, the free ACX spec guide covers the fundamentals.