If too many people try to enter a small area, the folks in the middle or up against walls cannot move, and are too crushed to breathe (and can suffer compression fractures and organ damage). Not only is it too loud to hear them, but they're likely too crushed to make a sound anyway.
Apparently a celebrity sighting triggered the rush. So far, over 150 dead and 80 injured reported, among them 19 foreigners; most are apparently female, and in their teens and 20s.
~~~~ Just another victim of the ambient morality ~~~~