My 2008 Alfa Spider has started making a high pitch whining noise which is related to the revs, the noise slows down quicker than the actual revs like something is spinning and rubbing against something. This happens when the car is in or out of gear.
Check the drive belt by pushing on it and looking for any obvious signs of wear. If loose or worn, replace it. If noise still there, remove belt and turn each pulley by hand. If one/more make a noise or doesn't turn absolutely freely with no resistance, replace.