Does it quit if you block all internet traffic?
My stereo system (giant 1980s vintage roof-shaker) used to pick up CB radio signals once in a while. I think it came in through the phono pickup.
Do you live near a broadcast tower? Or maybe you live next to a pirate broadcaster.
Okay everybody, don't laugh; it happens.
You can make a pyramid shaped hat out of aluminum foil
Seriously, I see your post is a few days old, did you figure it out yet?