What is a register?

"A register in the human voice is a particular series of tones, produced in the same manner(by the same vibratory pattern of the vocal folds), and having the same vocal quality"

How many are there?
"Research has revealed that the vocal cords are capable of producing at least 4 distinct vibratory forms, although all persons cannot produce all of them,
however, there are psychological advantages for the singer in thinking that the voice is all one piece.....the ideal is a freely produced continuum of beautiful and expressive sound"

Why does my voice sometimes break/crack when going from my lowest to my highest tones?
As pitch rises, the vocal folds are lengthened, tension increases, and their edges become thinner.
In other words, all three of these factors are in a state of flux in the transition. Laryngeal function tends to become
static, preventing necessary changes to take place and eventually breaks occur. 

How should I camouflage these segment breaks?
The adjustment needs to take place in continual increments from the lowest note to the highest in the modal voice-more energy, more space, more depth. If this is done properly, the segments will tend to disappear.

 

The Vocal Fry

The lowest register occupying the frequency range below the modal/normal register.It has a characteristic popping, frying or rattling sound that may be used to improvethe lower part of the modal register, however, excessive use can cause vocal problems.

 

The Modal Voice Register

Is the normal register for singing and speaking, sometimes referred to as the head voice.A well trained singer can sing two octaves or more in the modal register.The modal voice tends to have clearly defined segments or divisions in its total range-voices do not have the same amount of segements;men=3, women=2Men=chest + headWomen=chest+middle=head

 

The Falsetto Register

Lies above the modal voice register and is inherently breathy and flute like with few overtones present.The whole vocal cord is involved in the vibratory pattern of the modal register; this is not the case in falsetto.Example: YodelingTrivia: The castrato singers of the 16th through 18th centuries were male altos or male sopranos who sang in what was for themthe modal voice(the normal masculine voice change having been precluded by the surgical removal of the testicles). Thus, thecastrati were not falsettists but were modal voice singers with unique timbre and carrying power resulting from a combination of a femalepitch range with the body of a male singer.

 

Women have a falsetto. Young singers substitute falsetto for the upper portion of the modal voice and are often misclassified as sopranos.

Women who use falsetto in place of their upper modal voice probably shifts between Bb and F on the treble clef.

 

The Whistle Register

The highest phonational register above the female falsetto containing no overtones.