Distances

Why in the earth that when we're mad we tend to shout on the top of our lungs?

I came up with some possible answers at first. I thought we shout because we lose our patience. But why shouting, I mean this person we're mad at is just nearby sometimes. Can't we just tell her/him without rising our voice? I was stuck, as there was no answers that were good enough to explain it.

Until I came across this thought in a book: when two persons are in anger, the distance between their hearts is becoming further even though they may be physically close. Therefore to cope with that distance they have to shout. But the weird part is the louder they shout, the further the distance is becoming. Thus, they have to shout even louder and louder more.

And this is even more interesting thought. In the contrary, what happened when two persons are falling in love? Not only that they do not shout, but even when they talk they speak with soft and peaceful voice. And no matter how low the voice is, both can hear it very clear. Why?
It's because when their hearts are close to each other, there is simply no more distances. No words needed anymore. A glance right through the eyes will say it the best what they wanted to say.