I once heard an audio cassette of an actual exorcism, and it is quite creepy. You could hear the groans and threats of a demonic voice coming from within the person; not any such voice as Hollywood movies assign to demons, but rather like a gender-neutral wailing animated by a furious and violent hatred and eternal vengeance. The exorcist priests who deal with this stuff are the personification of faith and courage.
I am not making light of exorcism...but that sure sounds like what it looks like when one reads DU, too...