What changes physically when you sing?

Question:

What changes physically when you sing?

Recently I was wondering: What changes physically, when a singer change pitches?

It seems to me that you just open your mouth and the pitch comes out. From what I can tell, it's mostly a mental game, but still, something has to change physically to change the pitch. Sure there are exercises for legato, tone, vowel quality, range, etc. But how do human beings change pitch? Is it the vocal folds? The shape of the mouth? Does it have to do with the throat?

FYI: I'm a voice major in college, so I know how to sing (and do sing, daily). I'm not asking how to get better at singing. :-)

Just curious.

Best Answer - Chosen by Asker: If you are singing properly - everything should change when you change pitch. You brain coordinates with your ear and they both coordinate with your entire body. You know how to sing so you already know this.

The main pitch change comes from the shortening and lengthening of the vocal chords in order to adjust the vibrations per second. For pitch to rise, the vocal folds must vibrate more quickly. To do this, the folds get thinner by being stretched longer. To experiment, get a thick rubber band. When it is not stretched, it is like your vocal chords at rest. When you stretch it and pluck it, you get a pitch (this is like vibrating your vocal chords). If you stretch it more and more, the pitch goes up and up, just like your cords. If you reduce the tension, the pitch goes down.

Every voice can be stretched a little bit higher, but there is a point at which the vocal chords no longer come together. That is the lowest you can go. (There are some chord distortions that can result in other sounds, but everyone has a bottom). YOu can see this with the rubber band. If you stretch it a little bit then let out the tension and finally push the ends towards each other, you will see that the two sides of the rubber band eventually push apart. This is like singing so low you can't sing anymore (you might get a breathy sound on one or two more pitches but that is really just air blowing across the separated chords). On the other side, you can keep pulling the bands apart. This shows how most people have the ability to add a few notes on top but not on the bottom. You can stretch beyond comfortable. However, unlike the rubber band that can stretch until it breaks, your physiology will prevent your chords from ever streching that far.

I hope this helps!