Why shout???

A theology professor was teaching about proverbs 15:1. He asked his students, "Why do we shout in anger?  Why do people shout at each other when they are upset?

The students thought for a while. One of them said, because we lose our calm, we shout for that.  "But why shout when
the other person is just next to you?" asked the professor.

"Isn't it possible to speak to him or her with a soft voice? Why do you shout at a person when you are angry?"  

The students gave some other answers but none satisfied the professor. Finally he explained, "When two people are angry at each other, their hearts psychologically distance themselves. To cover the distance, they must shout to be able to hear each other. The angrier they are, the stronger they will shout to hear each other through that great distance.
 
Then the professor asked, "What happens when two people fall in love? They don't shout at each other but talk softly, why?  Because their hearts are psychologically very close. The distance between them is very small. The professor continued, "When they love each other even more, what happens? They do not speak, only whisper and they even get even closer to each other in their love. Finally they even need not whisper, they only look at each other and that's all....