FrisbeeSX

I have a 1992 240sx hatch I bought from some random guy who seems to have messed with electrical wiring in some way. When I have my radio volume up loud, my windshield wipers come on. This is no coincidence, because I have tested it. It can even be within a few notches of volume that makes them come on randomly, it just depends on the song I'm listening to at the time. They do not constantly wipe when this happens. They come on and wipe the windshield once or twice and then theyre off until it happens again. Normally I just keep my volume relatively low, or take out the fuse for my windshield wipers when the weather is nice. Anyone have any idea of why this could be happening? Thanks for any feedback