Non Digetic Sound

Sound whose source is neither visible on the screen nor has been implied to be present in the action: -narrator's commentary -sound effects which is added for the dramatic effect -mood music example: at 18.48 I think this is used here to help create a sense of uncertainty and uneasynesss which adds to the fact that we know something different and new is going to happen in this episode, but we dont know if it will be good or bad