Met
Measured, and inside the published requirement.
Audiobook and spoken word
Find out why a chapter would be returned, before you submit it.
Finality measures a narration chapter against the published ACX submission requirements, names the ones it misses in the units the spec uses, and can return a corrected chapter with every changed value reported against the number you were shown.
Three answers, not two
Not met
Measured, and outside it. The shortfall is named in the units the requirement uses.
Not measured
The value could not be read on this file. It is never reported as met, because an unproven requirement is not a passed one.
Why this lane is different
A spec someone else enforces.
Music has no spec to fail
A mix can be quiet, dense, or bright and still be exactly what you meant. Review gives you signals and you weigh them.
A distributor's target is guidance
Streaming platforms normalise loudness. Missing a target changes how a release lands; it does not stop it going out.
ACX is pass or fail
A chapter outside the published numbers is returned to the narrator. That is arithmetic, and it is worth checking before upload rather than after.
What gets measured
Seven published requirements, each reported with the value behind it.
Every requirement below is checked against the file you upload. Finality reports the measured value beside the requirement, so a result can be argued with rather than trusted.
Requirements and thresholds are read from ACX's published submission requirements page and are versioned with the date they were last verified. Finality measures against those requirements; ACX decides what it accepts.
The ACX submission requirements Finality measures
Programme RMS
Between −23 dBFS and −18 dBFS
Peak level
No higher than −3 dBFS
Noise floor
No higher than −60 dBFS RMS in the quietest 0.4-second window
Opening room tone
Between 1 and 5 seconds before the read begins
Closing room tone
Between 1 and 5 seconds after the read ends
Sample rate
44,100 Hz
File length
No longer than 120 minutes
Correction
A corrected chapter, re-measured after it is rendered.
Where a chapter misses a requirement, Finality can return a corrected file on request. Level is adjusted with the noise floor accounted for. Where level alone cannot reach the RMS window, a limiter holds the loudest peaks, and the change list says by how much. Room tone at either end is extended from the same recording's own silence or trimmed back into range. The rendered file is then measured again through the same analysis that judged the source, so the result describes the file you receive rather than the plan that produced it.
Your original is untouched
The original stays your primary download. A corrected chapter is an additional file you asked for.
Nothing is generated
Room tone is extended from your own recording's silence, or not at all. No synthesised audio enters your submission.
Limiting only where level cannot get there
A limiter is used only when turning a chapter up would push its peaks past ACX's limit. It never pulls a moment down by more than 6 dB. If it would lift the noise floor past ACX's limit, the copy is made without it and you are told why.
No approval claim
A corrected file carries no quality or acceptance claim. The decision to submit stays yours and is recorded as yours.
Chapter sets
A submission can be returned while every chapter passes.
A title is judged as a set, not only as files. Finality compares channel count, sample rate, and chapter-to-chapter level across a book and names the odd one out, because a set where every individual chapter meets the spec can still be inconsistent enough to be rejected as a submission.
A chapter with no measured result is reported as unjudged rather than quietly dropped from the set.
What this lane does not do yet
- Finality works on chapter-length files. ACX itself requires each file to be no longer than 120 minutes, so this matches the spec, but a single multi-hour recording is not supported.
- True peak after MP3 encoding is a stated limitation rather than a measurement. The peak requirement is measured on the audio, not on the encoded file.
- Finality does not upload, submit, or deliver anything to ACX, Audible, or any distributor on your behalf.
Check a chapter before ACX does.
Upload a chapter and see it measured against the published ACX requirements before you submit it.
Free to start. 60 minutes of review a month.
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