First: Carbonite has one map and it is either maximized (large, like Blizzards World Map) or minimized (minimap sized but NOT the minimap). Blizzard gives us three maps: The Minimap (found in the upper right corner of your screen), the World Map (the big map) and the Zone (sometimes referred to as the Battleground) Map. A technicality, to be sure, but it occasionally helps to use the correct terms when explaining something.
That said, is this happening constantly, or only in certain areas? I know it happens for me too, but only in certain areas. Usually, when it happens, if I maximize the Carbonite map the noise stops. Minimize it again and it comes back. It only happens until I clear that area, though. Like today I had it happen as I was flying into the Netherstorm zone in Outland.
Ahhhh, the vagueries of the aging mind. Wait.... What was I saying?