When I get fatigued (you know, fatigued for a fatigued person), I start to lose my voice. At first, it sounds like I've had a cold and lost it, then I sound like I screamed all night at concert the night before, and then I'm down to a whisper. Somewhere in the middle of all that, I might get a sore throat, but not every time. I have noticed that the worse it gets, the more it's like I just can't push any more air or volume out, not that my actual voice doesn't work.