This. I would assume copying a voice pattern is treated no different from copying an appearance. If a 3D model is a very close approximation to a particular person's face and you use it in a game intentionally to benefit from that person's likeness, you can run into legal issues. And of course you really open yourself up for a lawsuit if you then attach the real person's name to it.

EDIT: See the NPR Planet Money podcast linked elsewhere in the comments. Apparently there are fairly specific laws to protect someone's likeness -- including their voice -- thanks to the entertainment industry and Frank Sinatra.