Sounds like a strange electrical gremlin. The only real way to get a diagnosis would be to have an electrical/audio expert check it out. Make sure to note the EXACT circumstances it occurs (like bumps, certain turns or G-forces, etc). Otherwise, I've never heard of such a problem happening before.
"Why would I want to profess my feelings for some 3D girl?" - Tomoya Aki from the anime Saekano