I think this is partly his natural tone of voice and style of delivery. It also could have been cultivated for various reasons: 1) According to his own accounts, he was a wild and aggressive person when he was a kid. read more
3) He might have cultivated it for his political campaign, but I haven't heard anyone say that he used to speak more energetically, so I think this is unlikely. In any case, I am more concerned with what he says (scary stuff) than how he says it. read more