Belt Squeal
WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
Belt squeal is a high frequency air-borne noise generated by accessory drive belt slippage on the P/S pump pulley. Squeal increases with system loading and at the steering stops.