- Audiobook formats
- Files and labeling
- What to record
- Recording specifics (technical considerations)
- Children’s books
- A note on images
- Getting started
- Other resources
It is common for people to think that an audiobook is, by definition, accessible to readers with print disabilities. Since the text is recorded and audible, it is understandable to expect that there is not much else to do. But there are more elements to consider than just recording the book: it needs to be easily discovered, opened, navigated, and listened to – with the tracks in the correct order. This guide is designed to help audiobook creators design and produce audiobooks that can be discovered and enjoyed with ease, and to introduce the many points that should be considered throughout the process.
Accessibility in audiobooks is an evolving topic as technologies change and improve and our collective knowledge expands. At NNELS, we have been producing our own accessible audiobooks and working to support publishers in their productions. Our audiobook team includes Accessibility Testers, the Audiobooks Recording Coordinator, many diverse contracted narrators, and the Accessible Publishing & Resources Coordinator. Through varying approaches, trials, and challenges we have developed the following guidelines to give publishers a baseline of information as they create audiobooks.
Practices are not fixed, and different approaches may work better for some than for others, but the information in this document will hopefully offer helpful information that publishers can use to get started, as well as information which will prompt considerations and discussions helping publishers develop their own guidelines.
These guidelines are designed to create robust, accessible audiobooks, and provide readers with as much agency as possible. The opportunity to make choices, and have a say in one’s own experience, is a key element of what makes a book accessible.
Unlike for ebooks, where EPUB is the standard format, audiobooks don’t have a single standard for production and distribution. Currently audiobooks are a simple compilation of audio files, like MP3, MP4, WAV, as well as the DAISY format and Enhanced EPUB. That is about to change with the World Wide Web Consortium’s audiobook recommendatio, which will be the gold standard for quality, accessible audiobooks. In the meantime, here is a breakdown of the different formats currently in distribution and the way we recommend they are used.
|Recommended for simple, straightforward texts like novels, memoirs, and other books that have little or no supplementary material.
|Recommended for Academic texts, scholarly texts, and other books that contain supplementary material.
|Multi layered creation process can be labour intensive
|Recommended for children’s picture books.
|Playability has not been instigated in most reading systems (yet)
|Recommended for all types of books.
Chapter books, books of short stories, poetry, non-fiction, etc.
- Each chapter, short story, poem and section of the book should be a single audio file, i.e. copyright, epigraph, dedication, title page, chapters. Do not create a file per page (except in the case of single page sections), or only one file for the entire book.
- Each section filename should begin with the chronological number, followed by the title of the section, i.e. “03 Dedication” then “04 Chapter One”. Note, the name, author, narrator and publisher of the book will be stored in each file as ‘core metadata’.
- Save the entire audiobook playlist in a folder named the title of the book, i.e. ‘Alias Grace’
Children’s non-chapter books
- Each section should be its own audio file with the main story as one single audio file. e. title page, dedication, story. Do not create a file per page or only one file. Note, most children’s non-chapter books include images and there are a variety of ways to approach the inclusion of image descriptions which are discussed later in this document.
- Each filename should begin with a chronological number, followed by the title of the section, i.e. “01 Title Page”, “02 Dedication”, “03 Story”.™
NNELS guidelines on other texts, such as image-heavy texts like comic books and graphic novels, are in development.
Content: Book Sections
Unless an agency decision has been made to the contrary, almost all sections of the book should be narrated, including:
- front cover
- footnotes / endnotes
Footnotes/endnotes, bibliographies, etc. have commonly been excluded. They should be recorded, and incorporated in a way that works for the publisher and author.
Include a file for the front cover. This should include the title of the book, the author name, and any other text that may be on the front of the book, as well as a brief image description of the front cover.
Table of Contents
A table of contents is not necessary to record, as long as the files are presented in the correct order and have embedded track number information – that way, the reader has access to an overview of the contents of the book. However, including a table of contents causes no problems, so the choice is yours.
Foot/endnotes can be recorded in different ways.
Record notes together, in a separate file:
In the context of MP3 formats, one approach is to record the notes as a separate file per chapter, and placing the file after their corresponding chapter. The narrator would name only the note reference inline, for example:
“In AD 5, the Romans again stood on the banks of the River Elbe. Note thirty-seven.”
And then record all notes on their own, in a separate file.
The completed files would be presented as, for example,
- 01 Chapter One
- 02 Chapter One Footnotes
- 03 Chapter Two
- 04 Chapter Two Footnotes
This way, they are available to readers, while also being easily skippable.
Record notes inline (unskippable):
Another approach within the MP3 format is to narrate the footnotes completely inline for example:
“A chance inscription tells us that one of the legions in Cilicia had the numeral XVIII. (Note 16: Models of seigeworks undertaken by Caesar’s army can be seen in the Musée National des Antiquités, Paris.) From this evidence, some have discerned a clockwise numbering system…”
Record notes inline (skippable):
In the DAISY format, notes can be narrated inline, then tagged as such so that they are skippable for the reader while reading. This makes DAISY the most accessible format in terms of navigation.
Should image descriptions be included?
Whether or not to include image descriptions is a choice that the author and publisher should make together, whenever possible. The things to consider are:
- Are the images integral to the text, and contribute to the understanding of the book? If yes, image descriptions should be included. If not, then it might be acceptable to leave them out.
- Do the images contribute to the enjoyment of the book? For example, in a book about a family, perhaps there is an image of them having a snowball fight. If this is not mentioned anywhere in the text, it may warrant an image description, as seeing (or hearing the description of) this image contributes to the reading experience.
- Would an image description be obtrusive, detract from the narrative, or otherwise have a negative impact on the reading experience? For example, in the case of a fiction book, a drawing that demonstrates something happening in the text may be distracting to the reader, and take them out of the story. But, in the case of a non-fiction history of an old-west town, a picture of horses tied up outside of a saloon would likely add to the story, and would be unlikely to take the reader out of the narrative.
Writing image descriptions
When it is decided that a book will have image descriptions, they should be prepared ahead of time, and shared with the narrator in a separate document.
When preparing your descriptions make sure to stay within the complexity of the book i.e. don’t use words that are more complex than the primary text.
Here are some basic image description guidelines:
- Placement of objects in image,
- image style (painting, graph),
- names of people,
- placement of text,
- emotions such as smiling, and
- Descriptions of colors, such as red looking “vibrant and powerful”,
- obvious details such as someone having two eyes, a nose, and a mouth, and
- overly poetic or detailed descriptions.
For more detailed information on developing image descriptions, please check out the following resources:
- NNELS (July, 2020): Guide to Image Descriptions / Guide de description des images
- Cooper Hewitt: Guidelines for image description
- DIAGRAM Centre: an initiative of Benetech, has developed image description guidelines, a training tool, and more
- WEBAim: Alternative Text (geared towards content on websites but it has some great suggestions for writing concise alt-text)
Placing image descriptions
There are a few places that image descriptions can be included, and again, this is something that we recommend the author and publisher decide together.
When the images are integral
If the images are integral to the telling of the story, then the best place to include them might be as they come up in the text. It is important to indicate to the reader that the text is an image description so the description should begin with text that says “A photo of…”, “A drawing of…”, etc. It is important that the reader knows that the description is not part of the main text. Another approach can be to state “Producers Note” before a description, and “End Producers Note” when the description is finished.
When the images are not integral
If the images are not integral to the narrative, or perhaps don’t need to be shared as soon as they appear in the book, then it may be best to include them in a separate recording/section, similar to the footnotes approach. So, a book’s list of files may appear as:
- 01 Chapter 1
- 02 Chapter 1 Image Descriptions
This way, the reader can easily choose whether to listen to the section, or skip it.
The narrator should begin each section by speaking the title of the section i.e. “Copyright”, “Chapter one”, “Title page”. When applicable, the section titles should correspond to the items in the table of contents.
Some of the following information may already be well known to your audiobook producer. Nevertheless, if you are just starting out, it may be helpful to know!
Volume/level consistency is integral to guarding the safety of readers’ ears as well as avoiding level fluctuations that interrupt the reading process. The volume should remain consistent from chapter to chapter as well as from audiobook to audiobook.
Hums, hissing, buzzing etc. are straining to the ears and nervous system, especially over long periods of time (i.e. the length of a book). Use optimum recording techniques and equipment to avoid hissing and distortion.
Aim for a vocal tone that is warm and crisp. Warm tones are easier on the ears long-term and crispness brings clarity. Room tone and vocal tone should remain consistent throughout the recording.
Noises outside of the text can be very distracting for a reader and should be avoided, or if necessary edited out. Narrators should work in a place that is isolated from outside noises such as children playing, air conditioners running, etc. Narrators should also consider their own production of noise; physical adjustments in their chair, touching the microphone or stand, a lot of mouth noise from being dehydrated or having a cold, etc.
Specific audio requirements
These are the audio requirements we use for our audiobooks at NNELS:
- Include 1 second of room-tone at the beginning of every section and 3 seconds of room-tone at the end.
- Room-tone: Noise floor is at -60db maximum, i.e. close to silence.
- Level: Your recording should measure between -23db and -18db RMS (average) with peak values no higher than -3db.
- File type: If the audiobook is using stereo effects it should be exported as balanced stereo MP3s at 128-192 kbps. If the audiobook is only voice with no effects it should be exported as mono MP3s at 64-96 kbps.
A note on file size
Many commercial audiobooks are recorded at 320Kbps which is very high for a single vocal. We recommend 128-192Kbps for books with stereo effects, and 64-96 kbps for audio with no effects. This results in high quality audio with faster download times and smaller storage.
This is an important accessibility factor, as people that rely on audio for information may not have the storage for so much data, or the time/internet connections for long downloads. Keeping the file size low increases the accessibility of the file, without much compromise to the audio.
Including detailed metadata enhances accessibility by allowing the reader to easily know key information about the book. Embedding information right into your audiobook files allows for more playlist compatibility across devices and information access to readers outside of the playlist navigation.
The standard embedding of data for MP3s are ID3 tags. Because MP3s are primarily focused on tagging music, follow these guidelines below when entering your tags. Note that different production softwares have varying ID3 tag options. Using a specific tagging application such as “tag editor free” can be very useful.
Here are some approaches to audiobook ID3 tags
- Artist = Author’s name (First Name Last Name)
- Track = Name of section, i.e. Dedication
- Title = Name of section i.e. Dedication
- Album Title = Title of book
- Track Number = The track number that matches the file name, for example “06”‘ if the file name is “06 chapter two.mp3”
- Year = Year of production/audiobook copyright
- Copyright = year Audiobook published
- Genre = Audiobook
- Album Artist = Narrator (first name last name)
- Producer = production company
- Composer = Audio technician (especially in the context of a book with soundscapes/effects)
- Comments = Name of Narrator (First Name Last Name) and Publisher
The narrator should be a vessel to all of the print book’s information in audio form. With that in mind, take in the following considerations when selecting a narrator:
- Understanding of the text: It is very difficult for a narrator to successfully translate a book into audio that they do not comprehend. Narrators should work with content that is comprehensible to them.
- Tone: Tone should be consistent. Reading loudly exhausts the voice and will result in a changing in tone as the voice gets more and more strained and tired. Reading very quietly can be more challenging when the goal is a high-quality recording. Narrators should find a medium, conversational volume and tone that is comfortable for them to maintain throughout the length of each recording.
- Objectivity: Personal views should not impose on the tone of the text.
- Pronunciation: All text should be pronounced correctly (this is not inclusive of accents that narrators may have). Unfamiliar words and names should be researched by the narrator to support that pronunciation.
- Pace: Comprehension is the priority. Narrators should speak at a speed that is both natural to the narrator and considerate of the complexity of the text, i.e. if the text is a dense academic text it should be read at a slower pace.
Children’s books can often require special attention, as more work may be required to ensure that the listening experience is as engaging as possible. Illustrated children’s books may present a unique challenge when it comes to audiobooks, and will need to be approached thoughtfully. There is no one-size fits all solution.
Illustrated children’s books are very unique when it comes to accessibility. Often, the content, style, and format of the book will be a big factor in deciding how to best approach it, but there are multiple ways – and it should be a discussion between the publisher and author. Below we list two methods of approaching accessibility in enhanced, illustrated children’s books, but this is certainly not an exhaustive list!
Media Overlays with Image Descriptions
If the images are integral to understanding the story or depict things that are not mentioned in the text of the book, then including image descriptions is recommended. In this case, working with the author to write image descriptions that match the tone and style of the work would be ideal. The descriptions would be recorded at the same time as the text, and simply included in the media overlays.
Enhanced EPUBs are able to hold more than one audio track, so giving readers the option of “Read-along” and “Read-along with image descriptions” would ensure that everyone could have a rich experience.
If the images in the book simply demonstrate what is happening, or perhaps are too abstract to describe, you might consider adding music and/or sound effects to a book. This would include things like the sound of a motor or a horn if there is a car, the sounds of the landscape i.e. forest sounds if the images are based in a forest, animal sounds for animals etc. This would result in an enhanced experience for most readers.
No matter how the media overlays are recorded, or if a soundscape is included, accessibility best practices state that all non-decorative images must have image descriptions in the alt attribute of the image element, in the code. This ensures that no matter how the book is accessed/read (whether the reader plays the media overlays, uses a screen reader, or uses a refreshable braille display) they have access to all important elements of the book.
Of course, deciding whether an image is decorative or not can be a challenge, but we have some guidelines to help determine if an image needs alt-text. If an image is determined to be decorative, it will not need a description in an audiobook. To help determine if an image is decorative, check out NNELS’ Image Description Guidelines: Decorative Images.
In this resource, we have reviewed some of the many ways to improve the accessibility of audiobooks. This is an evolving area, and there are many aspects which will need to be considered and discussed by the publishing team, and sometimes the authors and illustrators. This guide should help ground your discussions, and help you make more accessible audiobooks!
- To help get started with narrations and recording, check out NNELS’ video series, Tips and Techniques for Audio Recording and Narration.
- To learn how NNELS approaches audiobook recording, check out our guide to Recording Audiobooks
- Read the W3C’s Audiobook Specification to learn about the developing standards for audiobooks