What do you do with a voice that is just not doing what the vocalist wants it to do? This can happen. Do you tell the singer that he can’t sing the music he wants to sing? Do you tell him he can’t sing it the way he wants to sing it because “he just doesn’t have that kind of voice”?
When training singers, if you have an open-ended agreement to work together until you get where you want to go and if the teacher is patient and the student is willing, almost anything is possible. Throats, people, bodies and minds are flexible. If you are in a limited time frame (like a semester at school or a year at a college) you might not make it to the “desired destination” but you can go a good ways toward it and have a plan that will continue after your student stops and goes out to sing on his own or to work with another (hopefully cooperative) teacher.
All of the many muscles in the mouth and throat have either a direct or indirect effect on what the vocal folds can do when air is passing through them as they vibrate. All of the muscles effect the position of the larynx in the throat and that effects the behavior of the vocal folds and the pharynx. The volume (air pressure and flow) will have an effect on the vocal fold amplitude (how much the vocal folds wave open and closed on each cycle of pitch), and that can be a distinct reaction, separate from vertical laryngeal position in the throat. Said another way, what your vocal folds do and how your larynx behaves are interdependent but can also be independent. You wouldn’t necessarily be able to track those differences directly, but they would show up as having the singing be “easier” and the sound “better”.
Since the larynx is suspended from the muscles of the front of the tongue and is also held in place by the constrictors (swallowing) muscles which form the side walls of the throat, all of these muscles need to release and “let go”, but there is no direct access to them, so then what? The only answer is to work with the muscles on the outside, ones that you can see and feel, until the response they make gradually goes deeper into the throat and work their way down. In order to stimulate change, all the muscles involved must be made to move, and move a lot.
If you gradually stretch the tongue starting with the front, the jaw and face muscles, in time they will move, release, lengthen and loosen. The soft palate (vela-pharyngeal port) muscles will not only lift and widen, they will do so more or less on their own and stay there without effort. This is accessed through the face muscles and through the mind (through anatomical imagery and vowel sound accuracy). The combination of these things — muscles moving, stretching, lengthening, releasing, and finally responding, also allows (gradually, over time) the vocal fold response to change — either becoming strengthened and energized or eased and relaxed (indirectly, over time). The end result, providing the teacher and the student know where they are going, will be the desired vocal quality which, when it emerges and stabilizes, will not only be stylistically appropriate, personally authentic and emotionally satisfying but comfortable to do.
Few who sing or teach have the opportunity to work this way but I have been privileged to do this many times. I can’t give scientific sources to say that this is true (there are none) but this is based on four decades of life experience teaching. You can accept what I say or not, as I can’t “prove” it. I write about it here to let people know that things that seem impossible might not be, given the right attitude and circumstances.