For any Android users out who want to use a text-to-speech engine other than Google's, I recommend Sherpa TTS
It's open source, offline, multilingual, and available on F-Droid.
I use text-to-speech a lot with my RSS readers (Feeder and ReadYou), and it's been a game-changer.
To get it working, download the app from F-Droid (here's more info on how to install F-Droid), or download the .apk to install it directly.
