I also noticed this problem right away after doing the patch upgrade today. There is no audio for the narration (ie. the speech audio). The music is playing and the text caption is displaying ok.
I have an original first version PS3 20GB.
I also decided to delete all my Dungeon Siege 3 saved games and game data to see if it helped. Upon restarting the game, it downloading and installing the patch again, the problem was the same.
I am surprised something this basic did not get detected by a QA team. I am looking forward to this being resolved and some great working updates to follow.