Dutas won't affect your voice nicki, not in the least.
The reports about Dutas and speech change were very rare and most likely not related (considering there are people who are born without those enzymes that dutas attacks, it's a genetic disorder).
The reports were about slurring speech, like you are drunk and can't finish sentences or you "forget" words momentarily when trying to finish a sentence like when you are drunk.
Those reported them, as far as I think I noticed, usually had also depression problem and living in a dream state.
They also had male sexual dysfunction, which led to depression which most likely led to the rest of the symptoms (I had depression causing me dream state for few months in the past).
So most likely there is no risk with that. There is the chance I am wrong, but seems like the FDA didn't bother adding those side-effects either, so they are most probably indeed psychological side effects OF a real side effect (sexual dysfunction most likely)