Not the coworker, but I've been doing this for a couple years. If you're on iOS, the simplest option is Voice Dream Reader [1].

It can read .epub files directly, along with text files and webpages, and integrates with Dropbox, Pocket, Gutenberg, etc.

On Android, you can get Voice Dream Reader (though it has less features than on iOS) or @Voice Aloud Reader which is free [2].

[1] http://www.voicedream.com/reader/

[2] http://www.hyperionics.com/atVoice/

It also works reasonably well for academic papers as PDF. Equations get butchered, of course, but overall it's not bad (you can set PDF margins so that headers/footers are not read out aloud on every page). I use it to proof-read my own writing, it helps you spot things that spelling/grammer checkers miss.

I have been doing this on Android for a few years using Ivona, FBReader with the FBReader TTS+ Plugin. I got Ivona (beta) from the Play Store before they were bought by Amazon - it looks like Ivona voices have since been pulled and are no longer available.

For Android take a look at this: https://www.youtube.com/watch?v=MAHg31ucDhY