Well, what makes something normal or abnormal is just statistics, really. The majority of people don't hear voices - so not hearing voices is normal. A small minority do hear voices - so hearing voices is abnormal. That doesn't really say much, though. (I'm in a very small minority of people that like the movie "Cabin Boy", so that's abnormal, too.)

I agree with Myself. Talk to your therapist about this. It's going to take some real work on your part to determine what these voices really mean.