I've been a Dean supporter for a year now. It has often struck me that what reporters have cited as rage appeared to me as Dean straining against his own vocal limitations.
If you've ever watched Dean closely, you may have noticed that all his vocalizations are generated from his upper chest and neck and not from his diaphragm. This is a very common mistake for singers and public speakers. The result is very predictable, you quickly become hoarse and you have to strain to achieve any volume. You'll also notice that Dean often seems to get out of breath, even in the relatively benign situation of a debate setting. This is because he is trying to speak before he has filled his lungs with any air, once again a result of chest breathing and not diaphragm breathing along with his own natural excitability.
I know this may sound a little hokey, but the fact is that I think Dean would really benefit from a little simple vocal coaching that would keep him from coming off in these appearances as a screamer and hot-head when all he's trying to do is communicate.