I used to hear voices coming out of my computer speakers when I lived in a remote area in Florida. It freaked me out too, but I finally recognized that the voices were using CB talk and I realized that because of my proximity to the highway, my speakers were somehow picking up CB frequencies.

I also remember in high school that a friend of mine had figured out there were very quiet voices from other lines bleeding through his line and he found a way to talk to them, like some kind of secret party line. It was strange, but just a by-product of some kind of technological bleed-through.