An unabridged audiobook is a word for word narration, usually by one person, of the printed book.

Abridgement is most often used to adapt a book into a narrated audio version.
Because books written for adults are generally meant to be read silently to oneself (which is usually much faster
than reading aloud), most books can take between 20 and 40 hours to read aloud.
Because many audio book consumers are looking to more quickly consume the information of a book,
and because of the high cost associated with recording and distributing 40 hours of audio,
audio book versions of novels are often produced in an abridged version.

Some party, usually an editor for the book’s publishing company,
will go through the text of the book and remove elements, notations,
references, narratives, and sometimes entire scenes from a book that could be
considered superfluous to the actual story or focus of the book in order to make its audible reading time shorter.
A fully abridged audio book can span as little as 4 hours for a book that would span 20 hours unabridged.

The easiest content of a fiction book to edit out is back story often provided for characters or story elements
that help support the reality of the story for the reader, but do not provide any narrative to the story itself.
For example, a passage such as “John sped away in his automobile, a red 1967 Mustang he’d purchased
from a junkyard and spent most of his college years restoring with his father” could be abridged
to “John sped away in his automobile, a red 1967 Mustang” or even “John sped away in his car.”

In a nonfiction piece, the most commonly abridged details are references, charts, details,
and facts that are used to support an author’s claim. While it would be unprofessional or
irresponsible to omit such details from a book, it is understandable for an audio book as it is assumed the
listener wants to hear the author’s opinion, and if he/she needs to check the details he/she may refer to the text.

Occasionally, an abridged audio book will be advertised as “Abridgement approved by the author,
“which would imply that the original work’s author has reviewed the trimmed down version of his/her work
and agrees that the intention or narrative of his story has not been lost, or that no vital information has been removed.

In many cases, an audio book for a popular title is available in both an abridged and unabridged version,
though the abridged version often is released first and almost always costs significantly less than the unabridged
version. Often, the two versions are produced independently of each other and may have different narrators.
Unabridged versions of books are popular among those with poor eyesight or reading skills who wish to appreciate
the entirety of the work, while the abridged version is more often referred by those who just want to follow the
story in a quick and entertaining way.

On the radio (for example, in British Radio 4 programmes as Book of the Week, Book at Bedtime,
Afternoon Reading, and Go 4 It for children), books are almost always fully abridged. Because of this,
if someone was trying to read along with the book, they would find it much harder than on an audio book.