Smart Audiobook Player is outstanding for listening to spoken word - https://play.google.com/store/apps/details?id=ak.alizandro.smartaudiobookplayer&hl=en_US

It costs $2USD but is worth every penny. Essential requirements for gobbling up audiobooks, lectures, podcasts, which this app has:

Ability to speed up audio any amount you so choose.
Skip forward or back both 10 seconds and 1 minute (essential for reading dense texts).
The ability to change its interface to a darker mode so it’s not like you’re staring into a lightbulb with those dumb bright/white windows.

Looks like this one is not available for iPhone so if you know of another comparable app through the iTunes store please let us know. Or if you have a dumb phone or no cell phone then good on you.

*Only negative thing about this app is how you find the files on your phone through the directory structure. Which is quite overly complicated.