Didnt the DK say in the into cutscene, that he though Sameul had stripped him of speach forever, but that he can telepathically talk to you??? He was tortured and ended up with no voice...
It might be that other DK's werent tortured by Sameul.
Seeing as I have started BD about 8 gazillion times, I think I have this part memorized! <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" /> Yes, in the cut scene the DK states he thought Samuel had stripped him of his speech forever (and right about now my hero is wishing he did - j/k LOL). But lo and behold, your character (the hero) can communicate with the DK telepathically. And he/she is the only character that can 'hear' him. (Other than the one who summoned him).
Faralas <img src="/ubbthreads/images/graemlins/mage.gif" alt="" />