Thanks chain, so it's not just the voice that's been affected.
Tigranes - I didn't play past the opening video. I was worried about there being other bugs. So, the only bug I encountered was the missing voice. By playing without downloading any updates though, the voice is present on the opening movie (and presumably on the cut scenes and ending, based on what chain said). It seems like, for the moment, playing without the game updates is my best option, unless the 14 MB of updates currently up for the PS3 fix more severe issues... Do they?
No problem. You got rid of the update in order for the sound to be restored just to be clear