4:33's Artificial Demarcation

It's interesting to see how a piece that invites the audience - and the musicians too, I suppose - to feel the spatiality of sound, its physical aspects, encourages an artificiality in the audience's demeanour - all that coughing! A commenter below the video wonders this too: is there always that much coughing at classical music concerts? There're a few "heh-hems" in between movements, for sure, but these seem to be coded messages of some kind. Not the Who Wants To Be A Millionaire?-type, mind, more a covert acknowledgement of the boundaries of the piece, even though objectively (problematic?) there is no change in the physical aural conditions of the hall from the last second of one movement to the first second of the little break. It's as if they need to mark it somehow, and because the piece is silent, there's no obvious demarcation between the piece and the not-piece, so they have to artificially create one.