Sometimes I hear tunes when the wind is blowing or the ac unit is running.
The other day, I was really getting freaked out because I kept hearing Beatles tunes and they were really clear! I looked outside for someone playing a radio, but I couldn't find any music source. As it turns out, I had taken my son's ipod away from him and I didn't notice that it was still playing, so I was hearing the tiny sound of songs from the ear jacks. I love the Beatles, but I was glad to find a logical answer!

Bluemountains