There are 35 muscles in the tongue. The larynx is suspended from some of them. That means that the tongue and the larynx are intimately connected. The jaw, also, has a relationship to the tongue and the larynx. You might think of them as a sandwich. Jaw on top, tongue in the middle, larynx at the bottom. (I don’t know. It’s what came to mind). The swallowing muscles, which function thousands of times a day on their own, have to be taught to remain in abeyance while singing. Keeping the throat open continuously is a very weird thing to do deliberately. Singng sustained long passages where one doesn’t swallow is the equivalent of doing a slow sustained arabesque…quite out of the ordinary, although lots of people learn to do both, OVER TIME. If you are a classical singer who has ever sung such passages you might have experienced that when you are done it takes a few moments for the swallowing response to come back.
The swallowing muscles constrict the side walls of the throat, allowing the larynx to raise and the epilglottis to flap over and cover the larynx so that food or saliva can move down the esophagus. They work to prevent anything caught in the folds to be expelled violently threw coughing (you cannot override this response). In order for these muscles to do their job they have to be free to move. Holding them still is a way to restrict their movement, so too much of that isn’t good. Keeping the vibrato out of a system that has one is also a way to hold the muscles still. Early music, barber shop, and jazz, all use deliberately straight tone and if the singer happens to have a natural vibrato, these styles ask the singer to “supress” it. OVER TIME, this can make free movement of the entire vocal system diffiicult.
If we go back to the tongue, the at-rest position of the back of the tongue (the part we don’t really feel) determines a lot. It affects the position of the larynx in the throat, and the amount of “tilt” in the thyroid cartilage, and hence, the pull on the vocal folds. Pressure on the back of the tongue also inhibits the soft palate from lifting, as the muscles of the soft palate wrap around in the back of the mouth starting underneath the tongue. Classical singers talk about “spinning” soft tones and “floating” them (ah, those “voice teacher jargon” words). This is only possible when the tongue base is released from the swallowing muscles and is actually free to adjust itself in the back of the mouth. Easier said than done. Singing a high note softly isn’t difficult if the muscles are loose enough to do this, to let go. BUT, singing loud asks the opposite…..that the musculature be “engaged” (activated) such that the larynx isn’t bouncing around. The laryngeal musculature has to help, as do the muscles of the jaw, mouth and tongue, and there has to be a good deal of air in the lungs and pressure on that air, for the loud sounds to be sung well, and not shouted. Therefore, these are opposite behaviors and it takes a lot of work to coordinate both ends of the physiologic scale such that all the muscles can make all responses, including the vocal folds. Most people are better at one thing that the other. Big voices sometimes have trouble with soft tones and flexibility. Smaller, light voices can fly like the wind and sing in hushed tones but wear out when constant volume is required. Fussing with the balance of these skills is required for all good singers, no matter what kind of music they want to do. It is a task that is tedious, and sometimes a pain in the neck (not in the throat!).
I have developed the ability to feel the muscles of the back of my tongue and mouth move them more or less independently. That sounds crazy, I know. I would be willing to have someone test me with either more electrodes or through X-ray photography, but I doubt that will happen. I have only this to back up my statement. The first time I had a fibre optic tube put down my nasal passages, I discovered that I could move things around in my throat by looking at the video monitor. I attracted a crowd at the Voice Foundation Symposium (where this happened in the early 80s). It seems that whatever I was asked to do, I could do. What I thought I was doing, I was doing, and it was clear that others saw this as well. Later, when I participated in more research, I repeated this many times.
I believe that we all have the ability to develop this type of responsiveness. Most of my students end up having very accute perceptions of what’s going on “in there”. This is the same thing that happens in bio-feedback. People learn to control body reactions through the feedback loop of what they see and hear on the “machine”. (Bio-feedback training is used to control high blood pressure and heart rate, and other conditions). It takes time, but it isn’t all that difficult.
I know from experience, both as a singer and as a teacher, that very small adjustments can make an enormous difference in the sound. It is possible to change the shape and position of the entire tongue, and of the other intrinsic muscles, and to change them deliberately. Learning to do this produces authentic stylistic changes, not imitation or manipulation. I don’t mind nit-picking with experienced professionals about getting these adjustments to show up (through changing the registration and the vowels). It’s the way to move from excellent to sublime.