Thanks for the responses guys. A teacher suggested this to me before school ended this last year as an idea for the school's haunted house next year. She is the head teacher for it. It's going into a three story building, and the point is to have this pulse emanate throughout the whole building. It doesn't have to be the loudest pulse on the third floor, but it has to be noticeable. This is just going to be playing a heart beat track over and over. I might have to go sealed... Any suggestions on that? I'm talking really cheap guys, around $20 a sub. I don't want to spend a fortune on it. It may be used once or twice in that application, though it would possibly make a hell of a SUV system.