Incidentally, I too would've answered the way Pascal did based on your first post, but the reason I say this isn't to chastize but rather because it would be the one obvious way to address your problem without starting over.

Find a voice-set you like, export all the WAV files for it, rename them EXACTLY as titled in the voice-set currently used by the character, and then do a batch import. Sometimes MM7View seems to crash when I am using the sound-stuff, but if I just ignore the "crashing" window, I can usually finish what I'm doing before the program tanks. (Small price for such a wonderful editor.)

Unless there is a way to do it with hex-editing, I don't know of any editors that allow one to change this more easily.

Something tells me you chose the high-pitched, super-annoying male elf voice, didn't you. "Talk to the hand!" he says.