I'm a deaf person with some speech training. When I dream, I rarely use sign language. I often notice myself talking verbally more often and sometimes even use "telepathy" to communicate with other dream figures. I think these dreams that I have is a reflection of my desire to be "normal" or at least mask the reality of my disability from myself.

I don't think it's unique to deaf people though, but we might be able to notice the difference better. How would you know whether you're using your voice or "telepathy" in your dreams?