Amazon’s Whispersync for Voice has been around for a while already, letting users switch effortlessly between reading e-books and listening to audio books without losing their place. Thus far, however, users of the Android and iOS apps have required the Amazon-owned service Audible app to make this switch. With Tuesday's updates, however, Amazon is bringing Audible into the main Kindle mobile realm, which means you can now switch immediately between reading and listening with a single tap, without leaving the book. This will be handy for those walking home, for example, who then wish to lie down in bed and start reading instead. Amazon says that narration is available for more than 45,000 Kindle books. To add this feature to your Kindle books, you can do so using Matchmaker, which scans your library to see which ones have an audio incarnation over on Audible.