I have written here before about the classical singers who have large voices and powerful delivery who move over to “non-classical” styles (CCM) and think all that’s involved is “changing the vowels”. This blythe assumption sits under their teaching.
Without looking at the default of their own instruments (and they don’t know what a “default” would be in the first place) they miss a crucial ingredient — that others, particularly those whose voices are not at all like theirs, do not have the equipment nor the capacity to sing outside certain sound parameters without significant “re-tooling” of their basic vocal production. Those students whose voices are quite different in size and color end up manipulating their throats to get the desired sounds. This becomes a form of imitation and precludes the singer ever having an authentic delivery or honest emotional expression in any style whatsoever. That there are singers who live their entire lives believing that manipulation is the essence of vocal technique is really sad but it becomes horrifying when those people enter a school system and start teaching.
It is possible to sing freely and authentically in a variety of styles but doing so typically requires very good training, time, experimentation and a clear idea of the vocal and musical goals one is striving to achieve. The people who manage to do this are often self-taught and figure out what works for themselves. They may or may not have a clue about how to teach someone else to do this and that’s the problem. If one relies exclusively on resonance and breath support as the primary tools to change vocal production, success will be elusive unless you have natural capacity to sing with great variety in the first place.
Most successful professional classical voices end up with a blend, balance or modulated middle register where pitches smoothly adjust from one kind of production to another in order to facilitate both range and resonance. You can’t really have a mainstream career if you don’t figure out how to sing through your middle range unless you are very low bass or a very high, light soprano or counter tenor. If you are a dramatic tenor, soprano or mezzo, you have to have some “heft” in mid-range (chestiness) as part of getting through the repertoire you are expected to sing. THESE folks, and only these folks, can learn to get through CCM styles by changing vowels in mid-range. They can do a decent job when singing in styles outside of classical as long as they stick to mainstream “American Songbook” rep. Rock, pop, gospel, and hard driving country music, maybe not so much.
Woman with big voices like Rosa Ponselle, Eileen Farrell, Leontyne Price, Marilyn Horne and several others, have recorded “non-classical” songs very effectively, but their recordings were modest and stayed within easy to adjust parameters. Debra Voigt, Renee Fleming, Kiri TeKanawa and others in more recent times have tried to sing outside their musical and vocal comfort zones with less success, primarily because their register adjustments do not allow them to carry their chest-dominant production much beyond A or Bb above middle C, if that. Years ago Placido Domingo sang with John Denver (“Perhaps Love”). Even though Domingo was able to scale his voice way back the vocal quality (resonance) of both voices in the same pitch range were not alike, although maybe the SLP (volume) was similar. If you don’t have ears to hear that Domingo did not modify his vowels and the vocal quality was completely different between the two tenors, then you don’t. This was a big divide and should not be mistaken for something else like — they have such different voices. Yes, well, maybe, but what they have MORE is different vocal production defaults that they could not deliberately change.
Further, if you are making up terms to describe what you do when you sing and teach, thinking that you have discovered something unique and special that no one else knows about or understands (happens every day), then you are dwelling on superfluous things that are valuable only to you and not helpful to anyone working in the music marketplace. There are five formants in the human throat and you can’t find something that easily falls outside of them if you are singing any sound found in most Western music.
Beware of teachers who are “classically trained” who claim to be able to teach you to sing in other styles if your own voice doesn’t match theirs in many parameters. Even if they sing CCM quite decently, that may not make any difference to you as a student. It ain’t just vowel sounds that need to adjust, folks. Nope.