Radio Static? or is it?

I have a 2005 pontiac grand prix gt. When I hit a bump in the road my radio makes this static noise. Sometimes the static sounds like it is coming from the front speaker sometimes from the back. If I hit the side of the radio on the passenger side, the noise will stop. The interesting part is that it doesn’t matter if the car is one or off, the sound persists. It doesn’t matter if the radio is completely shut off, the noise will persist. It doesn’t make sense to me. Can anyone help?

Defective radio is the most likely cause…There are other possibilities. Rodents chewing your wiring. A defective wiring harness. Bad ground connections behind the dash.