I have my ipod running through the front aux plug on my 08 silvy. when the radio is on, and in aux mode, i get a ringing through the speakers which increases as i accel. odd, and aggravating. let me know what you think.

 

Something is either screwy in the stock harness our your picking up interference through the headphone jack.

Try an FM tuner and see if the problem persists. Chances are it's the cord.

 

That's usually a sign of a bad ground.
Most likely in the cord.