i think it's music i hear. i'm always hearing something. i don't notice it until it stops, then i'm looking around to see who turned off the radio. i have actually went searching for the noise thinking i left a tv or radio on, and found nothing. i think it's weird. i don't mind it, since i don't really notice it until it stops. it's good to hear others hear stuff too, i thought i was just certifiably insane.