Andre Donegan, voice coach, has some good things to say to clarify what is meant by “phonation“. In case you thought it was another cell phone plan, here’s what he says: “Phonation is the creation of sound from air. A mostly mental process! If we wish to create a “good vocal sound“ we must first define that concept.

Good vocal sound is freely produced; loud enough to be heard easily; pleasant to listen to; rich, ringing, and resonant; energy flows smoothly from note to note: consistently produced; vibrant, dynamic, and flexibly expressive.
“Beautiful sounds start in the mind of the singer. If you cannot think
a beautiful sound, it is an accident if you make one. You must learn
to ‘picture’ the sound in your mind’s eye and ‘hear’ it in your
mind’s ear before it can become a consistent reality.”
This is easier to learn than one would think–working with an instrument, even a harmonica, can help a singer learn this skill faster. Play the note, then picture it, then hear it, then sing it. You will improve fast (which I heartily endorse, since my website is www.learntosingbetterfast.com!)
Another common misconception among singers about phonation is that if you open your mouth very wide, that will help your sound. The truth is, over-opening can cut down on your sound just as much as stiff jaws. Thinking of your mouth and throat as a sort of flexible amp, really works for me and my students. The mouth helps form the sound into words, which is created by the larynx and pharynx, to come out unimpeded and enhanced, like the bell of a trumpet. The pharynx and the larynx (love those words and please pronounce them correctly: fare-inks and lair-inks, not far-nix and lar-nix!) are involved in producing a good vocal sound The throat can really bring out the richness in your voice, especially if you lift your soft palate.(This is behind your hard palate–do the “snort” to feel it and relax it–just snort several times). The mouth delivers the sound that is produced, and it shouldn’t get in the way of the beautiful sound. Unfortunately, there is a culprit in the mouth that can thwart everything! (The secretly subversive tongue).
Most of us singers who are not born extraverts feel somewhat shy opening our jaws at all, though, and more shy pushing our tongues forward against our bottom teeth (the correct position for the tongue most of the time). I assert that it’s a subconscious thought: (“maybe if I hold my tongue back you can’t hear me make a mistake“) that inhibits the tongue from doing what it’s supposed to. As I always say to my students: Give the audience your tongue!
In review, to make sure you’re not tensing something (mouth, lips, jaws, soft palate, throat, tongue), sing a line of something challenging on an ooooooooooo. Then sing the same line on an “ah”. Try not to change your articulators much AT ALL, even though it’s a different vowel. Then try the words. Really try to FEEL (right brain) what you’re doing–don’t listen (left brain). Your jaws should be hanging down really loose; your lips should be “fishy” forward and flexible, and your throat “open” with your soft palate raised (yawn-y). The skill involved in all this is to keep your “amp” FREE. As soon as your left brain thinks (“oh, I’ll just hold my lips and throat open and stiff like this and I’ll sound like Kelly Clarkson”) you’re in for trouble.
I really recommend switching brains for singing–it’s such a great Quick Fix! One way to do that is to get so emotionally connected to what you’re singing (the whole point of singing, BTW!) and feel so much that you’re not hearing the left brain anymore. Another QF is to walk backwards as you’re singing. Do this when you’re not sure where you’re walking–don’t try to figure it out (left brain).
And one final bit of advice: please use both left and right brain when you sing next time: you’ll sound the best you ever have!