Is there typically a fireblock between every stud behind drywall?

What I want to do is install a home theater system but I don't know if I can fish the wires if there are fireblocks between every stud. The only way I'm going to know for sure is to try or get a stud finder (it's shipping actually) but are there generally fireblocks between every stud? If so, how would I fish speaker wires down the wall to the tv?