humming buzzing in speakers on 1990 Ford Taurus

there is a humming or buzzing in my speakers that wont go away

Asked by for the 1990 Ford Taurus
If the humming is in all four speakers it could be the stereo itself, if only in one speaker perhaps it is the speaker, (try substituting the speaker with another). Is the humming only when the engine is running if so it may be a problem of interference form the alternator.
Plug wires...any kind of open in the plug wires would cause EMI. electro magnetic interference in the sound system. Replace the plug wires and if that doesnt solve the problem then go to radio shack. they sell whats called a radio choke. it has a capacitor that absorbes the fly back volts should quiet the humming noise down.,