A weird sound "glitch".

So i was playing my singleplayer world, mining for diamonds. however, unusually i heard a radio static type noise, with some ambience in the background. (it's hard to describe the "song" that i heard.) however, this song is not in the game, and i didn't have my ambience / environment  sound's on. meaning what i heard, mightve been a glitch, or worse. after that i left the game, and then talked to a person on this Minecraft SMP discord server im on, we talked about it then i decided to delete my world. when i wen't into my testing creative world, the same ambience i heard wasn't there. meaning it was specifically in that world, and now im here. to talk about it to see if anyone else has the same problem as me