Audio Systems: Auto radio reverb sound., car sterios, radio reverb

Question
1999 Ford Expedition radio sound suddenly all audio, radio, CD's, tapes, all come out in a heavy "echo" type of reverb sound. Kind of like the reverb kids used to do to their car sterios in the 1960's, but this is something that suddenly started,and is not desired.
Is this a wiring short, a radio, or speaker electronics problem, or something else?

Answer
This is the frequency shaping IC gone bad, I think.  The amplifier may be bad, also.

Give the unit a hard reset just to see if that brings it back to baseline operation.  To reset you must remove power from the entire unit for a few minutes.  If you can find the power wires feeding the unit, pull one end of the wires off.

Cleggsan