Jay: I cannot much improve on your hypothesis about noise, except to add that a certain sort of diseased soul seems to find pleasure in it. Those crowds in Madison were not just using noise as a weapon; I suspect they rather enjoyed the ruckus. After all, it can be disquieting to be quiet. Best not risk it.
To that point, the hellishness of noise (or, obversely, the heavenliness of silence) seems to be a constant in our species’ literature.
Here is the Epic of Gilgamesh, written some 2,000-plus years before St. John’s apocalypse:
In those days the world teemed, the people multiplied, the world bellowed like a wild bull, and the great god was aroused by the clamor. Enlil heard the clamor and he said to the gods in council, “The uproar of mankind is intolerable and sleep is no longer possible by reason of the babel.” So the gods agreed to exterminate mankind.
And here is the demon Screwtape, Senior Tempter, in C.S. Lewis’s The Screwtape Letters:
We will make the whole universe a noise in the end. We have already made great strides in this direction as regards the Earth.
‘Twas always thus.