if you really want to freak yourself out, try riding with no helmet. (slowly, in a well known, safe area, etc). you'll be amazed at what you hear. the 919 (and i would guess most other bikes) makes many different sounds that (at least for me) are normally muffled by a helmet. when wearing a helmet i basically just hear the exhaust, clutch rumbling at idle, intake/injectors during acceleration, and some tapping at idle right before i shut the bike down. without a helmet i can hear all the various strange noises the engine actually makes. that quiet chain is actually clicking and whirring. the tires and brakes make all kinds of noises. you can hear the clutch engaging.
if you try this you may end up feeling a little silly after worrying about those faint traces of sounds you've been worrying about and trying to identify through your helmet (i did). when i read the (many) threads where people compare the noises their niners make, i think to myself that we're all riding the same bike, but we have different ears and helmets, which make a bigger difference in what we can hear.