After three years, he was desperately finding ways to inculcate the habit of maintaining silence. Each trying to speak louder and make one heard over the din. Screaming and shouting is a very normal way to attract attention, not just for children for adults too. Teachers scream themselves hoarse to a keep a class in order. Housewives nag their children while getting the homework done.
Collegians shout at each other as a matter of fashion.
Therefore, every individual creates excessive noise to be heard and registered. The practice of shouting is indeed unhealthy. Children need to be told the importance of keeping quiet and talking at a low-decibel volume. Otherwise, these highly talkative children grow into garrulous adults, which certainly do not make a civilized society. It starts at the very beginning.