Create top-quality audiobooks, and maximize your sales potential by providing the best overall listening experience.
Audiobooks uploaded to ACX must adhere to the following requirements. The ACX Quality Assurance team may reject titles that do not meet these standards, and their retail release may be delayed. The following requirements help ensure customers get a great listen.
Your submitted audiobook must:
Each uploaded audio file must:
- be consistent in overall sound and formatting
- include opening and closing credits
- be comprised of all mono or all stereo files
- include a retail audio sample that is between one and five minutes long
- contain only one chapter/section per file, with the section header read aloud
- have a running time no longer than 120 minutes
- have room tone at the beginning and end and be free of extraneous sounds
- measure between -23dB and -18dB RMS and have -3dB peak values and a maximum -60dB noise floor
- be a 192kbps or higher MP3, Constant Bit Rate (CBR) at 44.1 kHz
- When naming files, please use only standard US alphabetical/numeric characters. Please avoid the following:
- Nonstandard US symbols/characters.
- Some examples are but not limited to: ! # $ % & ' @ ^ ` ~ + , . ; = ) (ß ä ö ü Ä Ö Ü Æ æ Å å Ø ø".
Consistency in audio levels, tone, noise level, spacing, and pronunciation gives the listener an enjoyable experience. Drastic changes can be jarring to the listener and are not reflective of a professional production. This distracts from the listening experience and may lead to poor reviews and reduced sales.
Extraneous sounds can distract listeners from the story, and outtakes sound unprofessional. Each can elicit bad reviews and bad reviews can hurt sales.
At minimum, the opening credits must note the name of the audiobook, the name of the author(s), and the name of the narrator(s). Closing credits must, at minimum, state "the end".
Opening Credits Minimum Requirements
"[title of audiobook]"
"(subtitle if applicable)"
Written by [name of author]
Narrated by [name of narrator]
Closing Credits Minimum Requirements
This sample should start with narration, not opening credits or music. The sample must not include explicit material. This sample is used by customers to preview of your audiobook.
You'll be prompted to upload each file individually. Both the opening credits and closing credits must be separate files. This ensures listeners can easily navigate between sections, and that skipping forwards or backwards moves them forward or back one section.
This space is required to ensure titles are successfully encoded in the many formats made available to customers. It also gives listeners an audio cue that they have reached the beginning or end of a section.
These announcements help the listener understand what section of the book they are listening to without having to look at their player. If a section header is found to be missing during the ACX QA review, you will be contacted to make revisions which could delay the release of your title. Be consistent - a listener may think content is missing if most headers are read but some are not .
Put simply, all files must fall within a specific volume range. By keeping all files within this range - not too loud and not too soft - listeners won't have to constantly adjust the volume of their playback device.
By leaving this headroom you'll reduce the possibility of distortion, which can reduce the quality of the listening experience. This headroom is also needed to ensure files are successfully encoded.
Noisy files that contain background sounds and other distractions make it difficult for listeners to focus on the material.
Before going on sale in the Audible store, titles are encoded in a variety of formats that customers have the option of downloading. 192kbps (or higher), Constant Bit Rate MP3 files are required so this encoding process works without error. You may upload 256kbps or 320kbps files if you'd like, but the difference in quality heard by listeners will be negligible. Please see our tutorial for creating MP3s to our spec if this work is unfamiliar to you.
Submitted audiobooks may not contain both mono and stereo files. Stereo files must not be joint-stereo. Mono files are strongly recommended. Before being added to the Audible store, submitted audiobooks are encoded in a variety of formats that listeners have the option of downloading. Titles submitted with both stereo and mono files will cause errors during this encoding process and the title’s retail release may be delayed. We recommend mono for all of your files as this may prove to be the smoothest path that also allows for audio consistency.
Files over 120 minutes are not supported. If a section will be over 120 minutes long, find a good break in the narration and split the section into two files. A secondary section header must be included on continuations. If the section began with a header, such as "Chapter 2", we recommend starting the second file with "Chapter 2 continued". This will help ensure listeners can easily navigate from section to section.
ACX doesn’t accept text-to-speech or other automated recordings.