Apple is introducing automatic narration of select books in their library. I expect this to eventually be an automatic addition to every relevant book on their service although at the moment it appears to require a fair amount of manual review. Notice the “one to two month” lead time.
From Apple.com:
Apple Books digital narration brings together advanced speech synthesis technology with important work by teams of linguists, quality control specialists, and audio engineers to produce high-quality audiobooks from an ebook file.
Our digital voices are created and optimized for specific genres. We’re starting with fiction and romance, and are accepting ebook submissions in these genres.
Once your request is submitted, it takes one to two months to process the book and conduct quality checks. If the digitally narrated audiobook meets our quality and content standards, your audiobook will be ready to publish on the store.
The voice samples at the link above are really impressive. I hope Apple brings these speech synthesis improvements to other parts of their ecosystem. Safari’s built-in text-to-speech feature is shockingly bad in comparison.