Yknow, the power to mimic any voice doesn't sound very impressive, but combined with enough strength/intelligence/information, it is one of the scariest thing I can imagine.
This power is mostly used to decieve and lure opponents (through radio communication if possible). You can also catch people you're fighting off guard and create openings, make radio communication pretty much useless considering you won't know who you are really talking to.
Some additional things would be allowing this voice to appear from a certain radius from you. Something like luring someone for a sneak attack, messing with people's minds, etc. There are also frequencies that makes the target go insane after a period of time (not sure about this one).
You can also just use brute force and crank the decibels up to max to pretty much create a black hole, but this would also be a suicide attack, unless you have a way to deal with it. You can also break your opponent's ear drums but cmon, that's a bit boring.
The few problems that I've noticed is that
1: I don't think you can make the power of sound interesting in written form
2: Only having this power is kind of boring