I've seen this piece three or four times and it's always one of the most interesting things on the program.
First, you hear the sound of the room. This is a sound you never hear otherwise, because between acts they're always running the A/C as high as possible.
Then you start to hear people rustle the programs, because they don't know what's happening. Then more rustling, then whispering, and then the artificial coughs start.
Cage talked about writing that piece almost five years before he did. Then it took him two days to write when he finally decided to do it, because he was experimenting with times and ways of scoring it.
Cage was nothing if not genuine, and he also had a wicked sense of humor...