Which came first, the chicken or the egg? A quandary that no-one seems to figure out. However, for us as singers, thankfully the question of which is first, vocal cords or vowels, is one that we can answer!
The vocal cords are our first concern on a few levels:
So, what is going on with the cords is the focus. The registration – balance among muscles in the larynx responsible for chordal adjustment – is primary, with all other adjustments made as automatic responses flowing from the registrational adjustments. If the registration is disturbed, then all else becomes disturbed, like a ripple effect. If the registration is improved, then all else becomes improved.
Of course, during training, there is use of vowel, repetition of a consonant, or focus on tongue position to help re-education and healing of muscles. But, this is in service to free the registrational muscles so they can do their jobs, allowing all else to work better.
The registration is primary, but all the parts are interconnected and interdependent!