When a person is learning to sing in tune, meaning generally in the center of the desired pitch (not too sharp or flat or unsteady) pretty much instantaneously, we are witnessing a marvelous feat of coordination. Let's take a minute to just revel in the wonder of the human singing voice.
The primary muscle we use to control pitch is the cricothyroid. This muscle originates on the cricoid cartilage and inserts at the bottom of the thyroid cartilage. When it contracts, it pulls the thyroid cartilage down and a teensy bit forward, which elongates the vocal folds, allowing for higher pitches. When it relaxes, the thyroid cartilage goes back to its original position and we can sing lower notes.
Now, think for just a second about how small the vocal folds are. In female voices, you could lay the vocal folds across a dime, making them about 3/4 of an inch or 19 mm long. For male voices, the vocal folds could lay across a nickel, which is about 4/5 of an inch and 21 mm. Think about how many notes you can sing, and how that translates into the incredibly small and precise adjustments that the cricothyroid muscle must make in order to get to those notes accurately and instantaneously. This tiny muscle is an amazing thing! When we are learning to sing in tune, we are fine tuning this muscle's accuracy, which of course can take time. It never ceases to amaze me just how accurate the cricothyroid can be.
All singing begins in the brain, and for singers, that means we are often coordinating memory centers, language centers, emotional centers, speech motor centers, and all the life-sustaining areas of the brain.....ALL AT THE SAME TIME. I don't know about you, but using my brain to think about my brain is often overwhelming. It's just so neat how many things can happen all at once without so much as a second thought on my part. It just happens. Of course, there are things that can make the neuro connection either easier or more difficult depending on anatomy, training, and dysfunction, but there are very few people in the world who truly cannot sing or speak. It's nothing short of miraculous. I never get bored learning about this part of our singing journeys.
Of course singing requires breathing. In essence, singing is just a super fancy exhale. I have found a lot of singers really get hung up on the breath, though, and most of the angst about it is unhelpful. Breathing can be influenced by everything from body composition to trauma history, and sometimes if we hyper focus on the breath we end up doing more harm than good.
Still, to sing effectively, coordinating the aerodynamic aspects of the singing voice is needed. The breath can help us with dynamics, phrasing, range, and confidence. Plus, I have found that for some clients, playing with the breath can really help with body awareness when done in a sensitive manner.