Text to speech language change

How do I change which language text to speech uses when reading out loud? It doesnt seem to use the language property of the document, the UI languge setting, or the OS main (TTS) languge.
I use a pro version with English, German and French installed. Voice files for the os are installed for Swedish, English and German. So I want to know if I can change it to read a german pdf out loudly, or is it English only?