I think the voices are part of auditory hallucinations which are symptoms of psychosis. That could be for a number of reasons, not necessarily because of the progression of bipolar itself, but possibly the progression of a manic or depressive episode or as part of something else, but it is something only you and your dr can figure out. I think it is very important that you speak with your dr very soon about this so that you and he can figure out what to do.