This week I have worked on two sides of the same issue. One singer came in with a lifetime of singing with a natural vibrato. She wanted to learn how to eliminate it and had done so by the end of the session. Another singer, who told me not so long ago that she had never had a vibrato and couldn’t find one even when she tried, sang today with a nice steady vibrato which we have coaxed into showing up and that is continually getting better, which pleases her a great deal.
Vibrato is one of those things that is “somewhere”. It is a functional response of something to something else but science has not yet resolved exactly what makes the singing voice vibrato arise in those who have one, when it clearly isn’t there when those individuals are speaking. The research I did with Dr. Titze, wherein he had electrodes placed on my vocal folds so that he could run electricity through them, certainly made it clear to me that it was the vocal folds that were making the vibrato, but, sadly, the research wasn’t definite even if my own experience was.
Like a lot of professionals and skilled amateurs, I can sing a straight tone in all registers, I can sing it breathy or nasal, and I can turn it off and on at will. In my classical singing, I can, with some attention, keep the vibrato from being too slow. The vibrato rate is definitely different in classical than in CCM, although I don’t make that happen deliberately.
I have found that people with strong voices often have powerful vibrato responses and that they find it harder to subdue or inhibit it than do singers with more lyric, lighter voices. That’s just a tendency, though, not an absolute. The styles that use straight tone either a lot or all the time (Barbershop, Early Music, and Jazz), can end up affecting the natural vibrato of someone who has one by making it go away and stay gone. That is only a problem if the person singing wants to do other styles where the vibrato is expected, as for instance, in most music theater songs.
It is hard to speed up a big wobbly vibrato, slow down a machine-gun fast bleetly vibrato, or create a natural unmanipulated vibrato for the first time, but hard doesn’t mean impossible. Generally, the whole vibrato function is best left to Mother Nature’s domain most of the time, but learning to deliberately affect the vibrato for stylistic or expressive reasons is certainly possible and not a bad thing. This is contradictory, but true. Ah, the human body! Such a great and mysterious thing.