When I find myself with time to kill, I like to close my eyes and hear the soundspace
And after a while I hear it:
The background hum of the place
In this case it sounds like an air conditioner, although the air is not particularly cool. Then other missed sounds: dull distant thuds, exclamations of children; tappings, scratchings, crumplings, rustlings; keys, coughs, footsteps. It's like a modern symphony of percussive noises, not particularly beautiful, but nonetheless intriguing.