The idea that we should have smooth transitions between registers is an old one. Most classical pedagogies espoused the idea that smooth transitions were a sign of “good” technique and a mark of skill.
In the pedagogies that say you should only sing in one register or that there are no registers or that each note is its own register, you can have trouble with the smooth transition idea. What are you transitioning into and out of?
Simply put, if you don’t understand register function and so many singers don’t, you can get into trouble, you can end up trying to do something with “resonance” that belongs in the category called “register” and you can be truly lost in terms of understanding what you hear and feel while you sing or, even worse, while you teach singing.
Ethel Merman sang in one register most of the time. She could transition into a light heady mix in her high pitch range when she was young, but she lost that over time. Her vibrato widened as she got older and she ended up sounding like a parody of herself at the end of her career. Lily Pons sang primarily in head register for most of her range and it served her well to do so for decades. Most pop singers sing in some kind of chest mix and they can manage that for an entire career as long as they are careful.
Why the big deal, then, about “smooth register transitions”? Who cares?
The answer is that the vocal mechanism works best when it is free to move. Restriction of any kind limits what you can sing and how you can sing it. Currently, there are a great number of very popular pedagogical approaches in various styles of CCM that advocate pushing, forcing, holding, squeezing, constricting, and retracting all manner of muscles in the throat and body as a goal. AS A GOAL, folks. No smooth register transitions for them…..uh uh. They can just sing — high to low — in the same hamburger mash of whatever sound they can manage.
The idea that the voice can carry honest, heart-felt emotion makes some people angry. They have been taught that they have to portray emotion or portray feelings while singing. (Sing “like as if” they are angry or sad, rather than actually feeling sad, if the song is actually sad.) They have a vested interest in keeping the voice in a particular “place” that is deemed “correct” and anyone who suggests that this is not the case is suspect. But if you read the pedagogical literature, you will see that the old teachers, from Garcia and Lamperti to the more modern ones like Brown and Bunch Dayme do not advocate manipulation (the direct movement of any musculature in the throat), but rather advocate changing the sound quality or intention. They also advocate finding “pure” vowels, ones that do not distort. Many of today’s singers don’t even know what a pure vowel is and wouldn’t know if they were singing one if they were. Too bad.
Of course, you can get by without smooth register transitions. You can yodel from one register to another like Joan Baez or the young Joni Mitchell, or the 50s doo-wop singers who would flip into falsetto on high notes. Many people have had big careers with a big break right there in the middle of their range. Others have paid no attention to this vocal “smooth transition” response at all. Surely Peggy Lee didn’t think about singing through all her registers smoothly. She sang in a breathy mix for her whole life and it was just fine. If, however, you learn to hear register change as register change and not glom it onto other things, you will find that the singers with the widest range, the broadest change of dynamics and the most expressive colors are also the ones that change registration. This implies that they are also managing how they use their breath and that, in turn, implies that they are able to manage the body as needed as well.
If this makes you angry, you should ask yourself why.