Because they need to use the power muscle to squeeze more than wind energy and is very disappointing as well, thus making it clear than other syllables wok. Syllable is a heavy sound to sound level that is different from the other syllables that don't get down sound.
I need to use muscle power to pull over. And when the wind energy as well, making it very loud, very Quoc another syllable. Syllables are unstressed volume will be different from another syllable, not the unstressed.