2002 Ford Taurus high pitch noise

I've got this noise that sounds like a screeching noise. The car can be parked for a week and it still makes this noise. A mechanic unhooked the battery and it was making the noise still. He said it could be the radio or some sort of a electrical component draining off voltage
and said it would have to be taken to a specialist I've been told this by three mechanics so far and have had bad experiences with the ford dealerships in my area. Any help would be appreciated, thanks.

The car makes the noise all the time and comes from the dash board area in the passenger compartment loudest in the front seat area, can't tell which side is the loudest and you only hear it when the doors are open or when your in the car front or back, the key can be out or in the battery disconnected or not.