It sounds like some plastic is broken or loose....seems to be coming from the decoration strip and audio display....its quite annoying as its a new car and had not heard these kind of rattles in other cars which are quite older than mine....i talked to my dealer and he goes that there's gonna be some rattle but i hate it...
I can only hear this when I have the windows up, stereo and ac off. In other words no external noise. When the windows are down and or stereo is on then you don' there anything....
I'd like to know how many mazda owners have this problem....if its a common problem then i can't do much about it but if it is only a few owners then I'll have a point to argue with the dealer....