Singing Is Not a Mechanical Proposition
You'd be forgiven if you thought otherwise, especially if you have been immersing yourself in reams of voice science information.
What happens? Since most of this information is about "parts," one is fooled into thinking that manipulating the parts is the thing to do. Push on this or that muscle, or—and I love this one—"move" the air—and voila!—one obtains vocal nirvana.
Your voice does not need you to "move" air, lip-trill, or press on your abdomen, or any such nonsense. That's like shooting a basketball into a hoop with your eyes closed. In auditory terms, we're talking about the ear being closed.
What is one old-school approach? Calling with the clear desire to communicate. Calling to the friend across the street that you are surprised to see, haven't seen in 10 years, and can't wait to greet. Calling with quality, that is, with the intention to be heard clearly. (Need I mention that this isn't yelling?) Do this, and you will likely find that your ear will coordinate the parts without interference. Do this on a lower pitch and you will discover "singing position." Do this on an Italianate [a] — not easy if you speak in your nose or throat — and the throat will "open."
To be sure, old-school voice teachers have their tricks of the trade which one might be seduced into thinking are mechanical aids, but they aren't that at all—which one learns with long experience. What does one observe instead? That these same methods can be understood as involving a global response of the auditory system—a system which organizes the parts unconsciously.