How to Set a Playing Speed on Your iPhone for Audio Books
You can change the playing speed on your iPhone when listening to your audio books. You can choose to slow down the speed if you're studying, taking notes, or want to make sure that you listen intently and catch everything. Or you can increase the playing speed, essentially allowing you to speed-read your audio books.
Tap the Settings icon on the Home screen.
Tap iPod in the list of settings.
Tap Audiobook in the list of iPod settings.
Tap Slower or Faster to slow down or speed up audiobook playback.