[s-cars] chalkboard noise from speaker

[Dave Burig]

After sitting in the garage all weekend, (my car, not me) I turned on the
radio for the drive to work, and there is a noise coming from the rear
passenger speaker that sounds like someone dragging their nails across a
chalkboard.  The volume of the noise does not vary with volume knob
adjustment.  In fact, the noise is very prominent with the volume turned all
the way down.  Noise is there on Radio and CD.
Any help?
TIA
Dave ""Why don't you get rid of that thing and get something sensible like
my minivan"" Burig