‚Functional‘ is a very popular catchphrase in vocal pedagogy these days. I am hardly using it anymore and rather referring to Cornelius Reid as my teacher, even though he coined the term ‚functional voice training‘. Too often ‘functional’ becomes synonymous with ‘mechanical’, which would be the opposite of what Reid wanted.
Of course, he used the knowledge of the mechanism, that was brought on by scientific progress, as we teachers all should. But firstly his work was about training the ear to distinguish between the qualities of the chest and head voice and thus being able to diagnose the coordinative state of a voice. And secondly he found ways for approaching a voice and change its condition through principles, not method. So even if we know the function or anatomy, being able to change the condition of a voice is a whole other story; our body, psyche, mind and spirit are way too complex and interconnected for that.
As usual the whole topic is summed up pretty well by Cornelius Reid himself:
„It is one thing to know how the system works, another to know how to work the system.“