The Audiobook Production Process: From Recording to ACX Approval
Audiobooks are one of the fastest-growing segments in publishing, and more authors, narrators, and publishers are asking the same question: how is an audiobook actually made? The audiobook production process has three major phases: recording, editing and post-production, and uploading and distribution. Each phase has its own skills, tools, and standards, and skipping a step is the most common reason audiobooks get rejected or receive poor reviews.
This guide walks through each stage, including the technical specs you need to pass ACX quality control, so you can produce a professional audiobook or know exactly what to expect when you hire someone to do it.
Stage 1: Pre-Production and Recording
Great audiobooks start before anyone presses record. A little preparation saves hours of fixes later.
Prepare the manuscript and the narrator
The narrator should read the whole book first, marking difficult names, foreign words, technical terms, and character voices. Create a pronunciation guide and, for fiction, a character sheet describing each voice. Authors can help by flagging tricky terms and clarifying tone.
Set up a proper recording space
The biggest factor in audiobook sound quality is the room, not the microphone. You need a quiet, acoustically treated space with minimal echo and no background noise from traffic, appliances, or HVAC systems. Professional studios and vocal booths are ideal, but many narrators get excellent results with a well-treated closet or a purpose-built home booth with blankets, acoustic panels, and a soft, non-reflective environment.
Choose the right equipment
A typical audiobook recording setup includes:
A large-diaphragm condenser microphone (or a quality shotgun mic for some home setups)
An audio interface with clean preamps
A pop filter to reduce plosives
Closed-back headphones for monitoring
A DAW (digital audio workstation) such as Adobe Audition, Reaper, Pro Tools, or Cubase
Recording best practices
Record at 44.1 kHz, 16-bit or higher (many narrators record at 24-bit for headroom and convert later).
Keep a consistent distance from the microphone, usually 6 to 8 inches, to maintain a steady tone.
Aim for healthy levels without clipping, leaving headroom for editing.
Record room tone, a few seconds of silence in the same space, at the start of every session. You will need it for editing.
Stay hydrated, take breaks, and avoid dairy and caffeine right before a session to reduce mouth noise.
Record chapter by chapter, and re-record mistakes by pausing and picking up from the start of the sentence, which makes editing far easier.
A finished book can take roughly 6 to 8 hours of work for every finished hour of audio, so plan your schedule realistically.
Stage 2: Editing and Post-Production
Once the raw recording is complete, the audio moves into post-production. This stage turns a good read into a polished, consistent, platform-ready audiobook.
Audiobook editing
Editing is the process of cleaning up the raw narration. An editor will:
Remove mistakes, false starts, repeated takes, and long pauses
Reduce distracting mouth clicks, breaths, and lip smacks (without making the voice sound unnatural)
Make sure pacing and silences between sentences, paragraphs, and chapters are consistent
Match the manuscript against the audio in a proofing pass, flagging misreads, skipped words, or wrong pronunciations
Many productions use a separate proofer or quality checker who listens against the text, because a narrator and an editor are often too close to the material to catch every error.
Noise reduction and audio restoration
Even in a good studio, low-level noise can creep in. Editors apply noise reduction, de-essing, and gentle EQ to tame hiss, rumble, sibilance, and room resonance. The key is subtlety. Over-processing creates artifacts that make the voice sound robotic, and ACX reviewers will reject audio that sounds heavily processed.
Sound design and music
Most audiobooks stay simple, with a clean voice and no effects. But sound design can add atmosphere for the right projects, such as fiction, children's titles, full-cast productions, and immersive dramatizations. Options include:
Intro and outro music
Subtle ambient beds or sound effects
Voice effects for characters (phone calls, echoes, otherworldly voices)
Layered dialogue for multi-narrator or full-cast productions
Note that ACX typically expects minimal added audio, so check each platform's rules before adding music or effects, and make sure you hold the rights to everything you include.
Mixing
Mixing balances all the elements so they sit together naturally. For a single-narrator book this mostly means consistent voice levels from chapter to chapter. For productions with music, effects, or multiple voices, mixing means balancing each layer so the narration is always clear and nothing competes with it. Compression is often used lightly to even out loud and soft passages, and the goal is a listening experience that feels comfortable on headphones, in cars, and on speakers.
Mastering and optimizing to platform requirements
Mastering is the final polish. Here you make the audio consistent and make sure it meets technical specifications. For ACX, which feeds Audible, Amazon, and Apple Books, the key requirements include:
Loudness: Each file must measure between -23 dB and -18 dB RMS
Peak level: No peaks higher than -3 dB
Noise floor: No higher than -60 dB RMS
Format: MP3, constant bit rate (CBR) at 192 kbps, 44.1 kHz
Channels: Mono or stereo, but consistent throughout the entire book
Room tone: About 0.5 to 1 second of silence at the start of each file and 1 to 5 seconds at the end
File length: Each file must be under 120 minutes, and chapters should generally be separate files
Required files: An opening credits file, an end credits file, and a retail sample (typically 1 to 5 minutes)
Tools like the ACX Audio Lab, Audacity's ACX Check plugin, and Adobe Audition's loudness tools help confirm that every file meets the standard before upload. Always verify the latest numbers in the official ACX Audio Submission Requirements, since platforms can update them.
Stage 3: Uploading and Distribution
With mastered files in hand, you are ready to publish.
Prepare your files and metadata
Before upload, organize your files with clear, consistent names (for example, 00_Opening_Credits, 01_Chapter_1, and so on). You will also need:
Cover art: Square, at least 2400 x 2400 pixels, JPG, with the title and author name clearly readable
Title and subtitle, author and narrator names, series information
A strong book description and categories to improve discoverability
Rights confirmation: Proof you control audio rights to the title
Upload to ACX
In your ACX account, add or claim the title, then upload your audio files in order. ACX runs automated checks right away and flags files that fail technical requirements such as loudness, noise floor, or format. Fix and re-upload any flagged files.
ACX quality control and approval
After upload, the audiobook enters ACX's quality review. Reviewers check for:
Technical compliance with the audio specifications above
Audio quality: Consistent sound, no distracting noise, clicks, breaths, or audible processing
Completeness and accuracy: The audio matches the text, with no missing sections
Correct structure: Credits, chapters, and retail sample are present and properly labeled
Content and rights: No unauthorized material
Approval usually takes around two weeks, though timing can vary. If the book fails, ACX sends specific feedback so you can fix and resubmit. Once approved, you will confirm your final details and approve the title for sale.
Distribution and pricing
On ACX you generally choose between two distribution options:
Exclusive distribution: Your audiobook is sold only through Audible, Amazon, and Apple Books, with a higher royalty rate and a multi-year term.
Non-exclusive distribution: You keep the freedom to sell elsewhere, such as through other audiobook retailers and libraries, but at a lower royalty rate.
Terms and royalty rates can change, so review the current ACX contract before choosing. Many authors also explore wide distribution through other platforms to reach library listeners and international audiences.
Final Tips for a Smooth Audiobook Production
Invest in your recording space before upgrading your microphone.
Record room tone every session and keep your settings consistent.
Never skip proofing. Fresh ears catch mistakes the narrator and editor miss.
Test every file against ACX specs before upload.
Budget time for the review process and possible revisions.
Frequently Asked Questions
How long does the audiobook production process take?
For an average-length book, expect several weeks from first recording to final approval, depending on narration length, editing time, and ACX review.
Can I produce an audiobook myself?
Yes. Many authors self-produce using a home studio and free or low-cost software. Hiring a professional narrator and editor is a good option if you want to save time or reach a higher quality bar.
What is the most common reason audiobooks get rejected by ACX?
Technical issues, especially loudness levels, noise floor problems, and inconsistent audio between files, followed by audible processing artifacts and missing credits.
The audiobook production process may look complex, but breaking it into three stages makes it manageable: record clean audio, edit and master it carefully, then upload and pass ACX quality control. Whether you are an author producing your first title or a narrator building your career, understanding each step helps you deliver a book that sounds professional and reaches listeners everywhere.
Ready to start your audiobook? Share this guide with your production team, bookmark the ACX requirements page, and begin with a solid recording setup.