User blog comment:KATANAGOD/DavidVonderhaar Shows a Classified multiplayer Faction Voice on Soundcloud/@comment-4122733-20120516143156/@comment-356904-20120516184051

Simple logic. It makes more sense that he's voicing one of the soldiers in the OP with Shepherd who can see what is going on in the pit than Dunn who's in the trench and so cannot see a thing.