If you would like to speed up or slow down an audiobook's narration, you can do this directly within the free Libro.fm app.
Step 1: Tap on an audiobook cover in your library to start listening. Then, tap on the mini-player at the bottom of the screen to open the full audiobook player view.
Step 2: Tap the stopwatch icon in the bottom left corner of the screen.
Step 3: Choose from the available listening speeds, then tap Done.