IGN's RPG Vault has a pretty darn good interview with Tabula Rasa's audio team which includes Audio Director Tracy Bush, Mission Designer and Audio Associate Producer Rebekah Tran, and Lead Sound Designer Andy Brock. They examine a frequently underappreciated aspect of game design by talking about what type of music went with which areas and how weapon sounds were created.
Jonric: What are a couple of examples of sound elements that you regard as having turned out especially well?
Andy Brock: As far as what turned out well, I'm particularly pleased with how the robotic / mechanical creature stuff turned out. In development, the weapon sounds were pretty popular too, of course. Of those, I think my personal favorite is the AFS laser rifle. It was created by combining several synthesizer sounds and a field recording I made of an M249SAW being dry-fired.
Definitely worth a read to get insight into Tabula Rasa's audio, so check it out.