Audiobooks
How to prepare an audiobook chapter for distribution
A practical workflow for editing, cleaning, mastering, naming, and checking audiobook chapters before delivery.
Finish the performance before processing
Listen for repeated lines, missing words, page turns, mouth clicks, and edits that change the rhythm of the narration. Repair those problems before changing tone or loudness. A polished signal chain cannot restore a sentence that was cut too early.
Work chapter by chapter, but keep a reference passage from the first approved chapter. Return to it when a later recording session sounds brighter, darker, closer, or more distant. Consistency across the book matters more than making one chapter unusually impressive.
Clean only what distracts the listener
Reduce steady room noise and obvious interruptions cautiously. Heavy noise reduction can make consonants watery or thin, which is especially tiring over a long book. Compare the processed chapter with the original at the same playback level and keep the lighter treatment when both solve the problem.
Check breaths, pauses, and room tone as part of the performance. ACX currently asks for consistent sound and formatting, no distracting extra sounds, and one to five seconds of room tone at the beginning and end of each file.
Master to the distributor’s current specification
Do not rely on a generic music or podcast preset as proof that an audiobook will pass delivery checks. ACX currently specifies an average level between -23 dB and -18 dB RMS, peaks below -3 dB, and a noise floor below -60 dB RMS. It also requires every file in a title to use the same channel format.
Treat those values as delivery requirements rather than a reason to over-compress the voice. Measure the finished chapter, listen again, and confirm the current distributor specification immediately before upload because requirements can change.
Export, name, and inspect every chapter
Keep one chapter or section per file and use a naming pattern that preserves reading order. ACX currently requires 192 kbps or higher constant-bit-rate MP3 at 44.1 kHz, limits each file to 120 minutes, and asks for separate opening and closing credits.
Run the finished file through the distributor’s analysis tool, then play its beginning, a dense passage, a quiet passage, and the ending. Confirm the chapter header, file name, channel format, and order before upload. ACX Audio Lab can check measurements such as RMS, peak level, bitrate, sample rate, channel consistency, and spacing, but a listening pass is still necessary for performance and edit problems.