ACX Rejected My Audiobook: Common Reasons and How to Fix Them
Getting an audiobook sent back by ACX is frustrating, especially after weeks of recording. The good news: most rejections come from a short list of technical problems, and nearly all of them can be fixed without re-recording the book. Here are the most common reasons ACX rejects audiobooks and how to fix each one.
First, read the rejection carefully
ACX’s message usually names the problem and often the chapters affected. Note every file listed. Fixing only the first chapter and resubmitting is a common way to get rejected again.
1. Noise floor too high
The problem: background noise between words is louder than −60 dB RMS. This is the most common rejection for home recordings.
The fix: careful noise reduction using a clean noise profile from your room tone, followed by re-mastering. Avoid aggressive settings that make the voice sound watery. If the noise is very loud (traffic, fans, hum), the affected chapters may need professional restoration or re-recording.
2. RMS loudness out of range
The problem: chapters are quieter than −23 dB RMS or louder than −18 dB RMS.
The fix: gentle compression and loudness normalization to around −20 dB RMS, then a limiter to keep peaks safe. Raising volume also raises noise, so check the noise floor again afterwards.
3. Peaks too high
The problem: peaks go above −3 dB, often from plosives or sudden loud lines.
The fix: a limiter with a ceiling around −3.5 dB on every file. If you hear crackle or distortion, the recording itself clipped and those lines may need pickups.
4. Missing or uneven room tone
The problem: files start or end abruptly, or use digital silence.
The fix: add 0.5–1 second of natural room tone at the start and 1–5 seconds at the end of every file, and replace any digital silence inside chapters with room tone.
5. Inconsistent sound between chapters
The problem: ACX’s human reviewer hears a change in tone, volume or room between chapters — common when recording over many weeks.
The fix: match EQ and levels across the whole book during mastering so every chapter sounds like the same session.
6. Wrong file format or structure
- Files must be MP3, 192 kbps or higher, constant bit rate, 44.1 kHz.
- All files must be the same channel format (all mono or all stereo).
- Each file must be under 120 minutes.
- Opening and closing credits must be separate files.
- The retail sample must be 1–5 minutes with no explicit content.
7. Audio doesn’t match the manuscript
The problem: missing lines, repeated words or chapters out of order.
The fix: a full proof listen against the manuscript, a pickup list, and re-editing the affected sections.
How to resubmit
- Fix every file listed in the rejection, not just one.
- Check all files again with an ACX check tool for RMS, peak and noise floor.
- Listen to the start and end of each file for room tone and clean edits.
- Re-upload the corrected files in ACX and resubmit for review.
Get it fixed fast
If you’d rather not spend days in an audio editor, send us your rejection email and files. Our ACX mastering service diagnoses the issue on a free sample, re-masters the book to spec, and includes a compliance report. If ACX flags a technical issue on files we mastered, we fix it free.
Want your audiobook ACX-ready without the guesswork?
Send your ACX rejection email and one affected chapter. We’ll fix it free as a sample and quote the rest of the book.
