I have observed that, for some reason, I often connect this phrase to the thymus gland, which is at the top of the lungs, although I know that "top" in this phrase refers to the degree of volume of the voice/sound.

(I have the right to believe whatever I want!)

The thymus gland is connected to the immune system/fighting infections.

So, my mind somehow sees that when we yell, scream, sing loudly, etc., we express powerfully or forcefully the need of being lighter/ of taking out whatever needs to go out because if it stays in and we can't process it, it will be transformed into illness.

Or, we also express the fact that we made it; we managed to be healed from an "infection" .

"Now we're free, free".

: )