I know that this is the reason why Dad is travelling 6,000 miles (from Ohio to Los Angeles and back) just to get the collagen injections. I think my brother-in-law said it best: "Dad can't enjoy conversation", meaning that he can't fully participate in spoken conversation. Sometimes people feel that just because the person can't talk, they can't understand what others are saying to them or what's going on around them. I have to explain this almost constantly to others in our school about one of my students (his cerebral palsy affects everything, including the ability to get the air through his mouth and nose at the right time so he can speak, and also the ability to place his tongue). People are really surprised when I tell them that this boy is of at least average (or above) intelligence. They ask me how I can tell, and I say that the way we communicate with him is by asking him questions and having him look at certain places in the room for his answer (i.e. "If your answer is 'red', look at the door; if it's green, look at the window"). Sometimes he even teases us by purposely giving a wrong answer (he smiles very slightly before looking at the wrong answer!). So there are also other ways to communicate when the voice isn't up to par!