Okay I know it looks weird! but that's singers' musical instrument. Our vocal cord. And this is how it works.It vibrates everytime we make sound. Number 1-6 indicate when we don't make sound. Number 7-9 is when we start to make sound. You can see that the vocal cord coming closer to eachother.
*please consult you doctor for full detail*
How does it work when you sing loudly?
And from my understanding in speaking or singing louder is that if you want to make it louder, you just need to hold your vocal cord against your breath longer before releasing it. The longer your vocal cord hold it together the louder sound you can produce. So imagine what will happen if your vocal cord needs to hold against too much breath? It will flip or it gets injured because it overworks. That's why your throat hurts after shouting.
How does it work when you sing higher pitch or lower pitch?
Think of a rubber stick. It becomes thinner when you extend it. And if you try to make sound out of it, the sound is gonna be in high notes or , you can say, smaller size.
Think of Piano, harp, or strings. The lower pitch is made of a shorter material and the high pitch is from the longer one. This is true about our vocal cord as well. It extends and vibrates nicely, tightly (not too tight) to create a nice strong high pitch. If it vibrates loosely but still extends, you will get the breathy high pitch. And you will get your nice low pitch when it's not extended and vibrates tightly (again, not too tight), and a breathy one when vibrating loosely.
