Symantics aside, however you define vocal registers, boundaries and breaks, the important thing is how to blend your voice to get rid of the cracks. Added bonus... eliminating vocal breaks also adds to the tone quality of the voice through out the whole range, helps to relax the voice into a fuller range and adds to vocal control.
...The frequency of vibration of the vocal folds is determined by their length,
tension, and mass. As pitch rises, the vocal folds are lengthened, tension increases, and their thickness decreases. In other words, all three of these factors are in a state of flux in the transition from the lowest to the highest tones.
If a singer holds any of these factors constant and interferes with their progressive state of change, his laryngeal function tends to become static and
eventually breaks occur, with obvious changes of tone quality. These
break are often identified as register boundaries or as transition areas between
registers. The distinct change or break between registers is called a passaggio or a ponticello.
Vocal pedagogists teach that with study a singer can move effortlessly from one register to the other with ease and consistent tone. [Judy says, absolutely!] Registers can even overlap while singing. Teachers who like to use this theory of "blending registers" usually help students through the "passage" from one register to another by hiding their "lift" (where the voice changes). However, many pedagogists disagree with this distinction of boundaries blaming such breaks on vocal problems which have been created by a static laryngeal adjustment that does not permit the necessary changes to take place...
I have been able both to get rid of my own vocal break and to help every student I've worked with eliminate theirs with the teachings of Power, Path & Performance personal lessons and cd course. That's how I know it works.
Now check out the next 2 posts in this series:
2. Ways to mend a pesky vocal break - part 2
3. Ways to mend a pesky vocal break - part 3