A general look into phonation:
What happens when we say a vowel, AH for example:
From the point of view of the speaker, and the process you do consciously, your answer will be probably: I just say it. Indeed that’s all you *will* to do it.
However, to “just say it”, the following process happens.
The vocal folds open;
The diaphragm contracts and descends, since its separating your abdominal cavity from your thorax, the thorax space increases, and this lowers the internal pressure of your body;
Muscles on your thorax and neck contracts and expand the rib cage, also expanding the thorax and lowering the pressure further;
The air flows inside you, filling up your lungs. When this happens, the pressure inside you is again in balance with the outside air;
The vocal folds come together;
Your jaw opens;
Your lips open;
Your tongue is lowered towards the floor of the mouth, and moves backwards;
The soft palate lifts and closes the nasal port;
The diaphragm relaxes and the ribcage collapses, this makes the thorax space smaller again, and the pressure inside you higher than the outside;
Air pressure is therefore applied against the vocal folds;
The vocal folds keep just enough tension so that small pulses of air are released periodically, but no so much to halt the release of air completely;
Different balances of tensions and lung pressures will result in a different mechanical register. The possible registers are M0 (fry), M1(modal voice, full voice), M2(falsetto, head voice*), M3(whistle);
The resonance of the vocal tract, set by the space on the pharynx, mouth and lips, amplifies certain harmonics from the base sound produced by the folds;
The harmonics that are reinforced by the resonance result in the vowel we hear, those are known as formants;
The formants that are more meaningful for vowel perception are F1,F2 and F3, the first three in the series and they correlate to pharynx, mouth and lip space, respectively.
So you see that “just saying” AH is a complex coordination, and this is a very rough description. There is more, for example articulators we are not using to coordinating, etc.
*male full head voice is done on register M1
Consider then the role of breathing:
As it was said, it’s where the process begins, by the inhale of air. And its the air that will provide the power to the instrument.
Also, notice that the control of registration involves lung pressure, and therefore, air flow.
I will add more information now:
The higher the pitch, the more pressure is necessary;
The higher the pressure, the louder the volume;
Also, there is one very important thing about our larynx. You see, the larynx is a very capable “device”.
Whatever you attempt to do, it will try to find a way to do it. It’s the central part of phonation control. This means that it will effectively COMPENSATE for whatever you do that is not optimal. From breathing to resonance.
Although this is great during speech and other less demanding tasks, on singing it will lead to forcing and even hurting the soft tissue/vocal ligament. Get used to it, and your chances of developing a chronic abuse situation is high.
There is one concept in technique known as attractor states (which comes from dynamic analysis). The idea is that on complex systems, the global state of the system will gravitate towards a usual setting, and will persist being so.
Attractor states is one of the reasons different people have different points of difficulty and also why some people seem to get it so easily. It also means it’s very easy to get used to a not optimal, or even poor, coordination without noticing there is something incorrect about it.
Breathing is your source of power. A stable and precise flow of air is necessary to make phonation efficient and use the absolutely minimal muscular effort for a given result. The larynx role during phonation is to produce sound, if it also becomes responsible for regulating the flow, you will be effectively compensating for a poor coordination of your breathing.
And that’s the definition of support:
Using an adequate pressure and flow for a given phonation, whatever that phonation is.
However, also notice that what I am talking about is developing coordination, improving it. It’s not about “singing from the diaphragm”, it’s not about forcing down, up, it’s not about holding back.
I say this because I see a lot of people making claims about how support is a “technique” that can fix all your issues and lead to “superior” quality. This denotes lack of background and even proper control of the concept.
So I will break down the process of inhaling and exhaling, and I will suggest approaches for training and improvement based on that, also some common techniques used to organize it. As always, training of these aspects is best done with a teacher that is familiar with the fundamentals.