I had a curious thing on my Mac, that in different Apps the Text to speech was different than in MSWord.
I find out, that this comes from Accordance, I switch there to test on a greek voice.
The funny and/or annoying thing is that, that the greek and the and hebrew voice don't work in Accordance. But in another Apps (like http://www.condenseapp.com)the preferences from Accordance is to dominant and overwrite there the system preferences even if Accordance is closed. MSWord take always the voice from the Mac preferences.
Thats the opposite of what Accordance has to do.
Hope this helps to debug the text to speech function in Accordance.