I have noticed within the last 2 days when My car is driving and I hit a bump it sounds like a rattle is coming from the rear speaker directly behind my head when I am driving. Might be somewhere else but thats what itsounds like. I thought maybe its loose or the speaker itself is going bad. I got out of the car while it was off and starting tapping the speaker grille and seats and there was no rattle. Later I drove it after weather warmed up and there was no rattle. Im not concerned because it seems to go away, but I am curious to what the rattle is?