The topic of formant/harmonic tuning is a very hot one in voice science circles these days. It explains a lot of what we hear as sound in various vocal qualities and gives us clearer guidelines about how the vocal tract is functioning acoustically.
Knowing, however, isn’t doing. Knowing is learned through trial and error by listening and feeling over time, hopefully with educated eyes and ears nearby to guide you. Only singing can teach you to sing, just like dancing can teach you to dance, playing can teach you to play (an instrument or a sport) and acting can teach you to act. It isn’t possible to be good at anything by knowing about it. It’s not like arithmetic (which doesn’t change and can be learned from a book) or by any of the hard sciences which are definable by math, geometry, physics or the laws of the universe as we presently understand them.
The same can be said of music. You can learn to play or sing notes, you might even learn to make them louder or softer or sustain them for a longer time. You cannot learn to be musical or expressive by making pitched-based noises. There is an element of sensitivity required that might be cultivated but in some people it’s just how they react naturally. Someone like me, who never worked on being expressive with any coach or teacher, who had to learn to control my reactions not develop reactions, is a natural in the sense that the music does a lot of the work. Singing in this way is not difficult, and can be very fulfilling.
Can I line up my formants and harmonics? I suppose so. If I have the right equipment and I understand what I’m doing, could I align them in specific ways? I guess. Do I need to do that to be a good singer? Nope. It’s good to know and to understand. It’s useful to grasp the material world’s functional parameters including those that occur in the body. Does that help me sing? No. Does it help me avoid stupid explanations about what happens when I sing? You bet!
If you understand registers as both feeling and sound, and if you can adjust the shapes in your throat and mouth, including your face, your jaw position and your lips, all you need to add is volume, pitch and duration. Being artistic, however, is not found in those ingredients nor is it to be discovered in formant/harmonic tuning or open/closed quotients. It’s found in your body, your heart and your imagination.