Hey, yeah, Bart is a professional musician/composer so he knows what he's doing! Not everything you see in-game is custom-made, that would take way too much time. The assets are always modified to suit the story and timeframe though. David knows what he's doing - working on the lighting as well. I presume it's real-time - maybe that's why it gets choppy here and there :/
Me? I not sure I know what I'm doing! :P