Whole-book QA
Drop the folder your chapters live in: each one is checked against ACX and against the book’s own median, so one noticeably louder or noisier chapter cannot hide behind its own green checks. The ones that can be fixed come back corrected and re-measured, as a ZIP or straight into a folder.
No book to hand? Try a sample:
One at the right level, one too quiet, one recorded in a noisy room. Synthesized by this site rather than recorded.
Ready.
| Chapter | RMS | Peak | True peak | Noise floor | Channels | ACX | Book match |
|---|
Two different questions
Every chapter below passes ACX on its own. Two of them still do not belong to the same book, and only a comparison against the batch median can say so.
Where the lines come from
RMS, peak, noise floor, room tone and encoding are reported per chapter from the official ACX audio submission requirements. A chapter either meets them or it does not, and that verdict does not depend on the rest of the book.
ACX also asks for all mono or all stereo files across the book, so a batch that mixes the two is flagged here — each file is fine alone, and the book is still wrong.
Separately, a chapter is marked when it lands more than 2 dB from the batch median RMS or more than 4 dB from its median noise floor.
Those consistency thresholds are editorial review flags, not ACX rules. The report says so in the same words.
Not blind, and not silent
The fix pass here is the single-chapter fixer run once per failing chapter: each corrected file is re-encoded, then re-opened and measured again the way ACX will, and a chapter whose corrected output would still not pass is declined by name in the table rather than slipped into the ZIP. A chapter whose verdict is a re-record is never touched at all — software cannot take the room out from under a voice. Fixed files are held in memory until the ZIP is written, so for a very long book on a small machine, fix the worst chapters one at a time instead.
Straight answers
Drop the folder your chapters are in, or pick the files. They queue and are checked one at a time against ACX, and each one is also compared with the book's own median level and noise floor. Cover art, notes and anything else that is not audio is ignored rather than counted as a failure.
That chapter sits more than 2 dB from the batch median RMS or more than 4 dB from its median noise floor, so it will sound different from its neighbours even if it passes ACX on its own. Those two lines are this site's review flags, not ACX rules, and they need at least three chapters to mean anything.
Every failing chapter that can be fixed is corrected, re-encoded and measured again, then collected into one ZIP or, where the browser allows it, written straight into a folder you choose. A chapter whose corrected file would still fail is declined by name in the table, and a chapter that needs a re-record is never touched.
Yes. ACX asks for all mono or all stereo files across a book, so a mixed batch is flagged as a book-level problem, and two files with byte-for-byte identical contents are flagged as duplicates, which ACX's Audio Lab rejects too.
No. Each chapter is read inside this browser tab, one at a time, and the JSON and CSV reports are written in the tab as downloads. The tools on this site never upload your audio.