So this is something that has been plaguing my curiosity for most of my life. This usually happens when I am tired. What happens is my brain will playback a sound, usually a few words of a song or a short sound bite of it (average of 3 seconds), over and over again. It will be trapped in an endless loop until I either find something else to repeat to myself, clear my mind or concentrate my thoughts elsewhere. It’s not super annoying but it can be bothersome at times. My question is, psychologically, why and how does this happen and is there an official name for this phenomenon?