Is there more than one method of teaching and studying voice?
Unfortunately, yes.
There are as many “techniques” as there are voice teachers, and many people who think they understand vocal production are actually operating from a flawed “self-taught” perspective.
Many of my students come to me with an “idea” as to how to sing. I spend a great deal of my teaching time changing habits that don’t work, usually put there by bad teaching or trying to “self” teach. Many students are in the habit of relying only on what they hear and trying to copy those sounds.
These students miss the concept that singing is as much about feeling as it is hearing the sound. If a singer has a positive “feel” for a note, then much of the time an audience will hear a correct -on pitch- sound. This is not always true, but as a general rule the feeling of ease and clarity of words work hand-in-hand to produce successful singing.