Scenario one: A singer in training begins a note beautifully soft and attempts to crescendo. S/he gets to about mezzo-forte and the voice cannot go any further? Comment from the singer: “I could not get it to full voice!” Is that a correct assessment?
I think not! To understand why, we must first define what full voice is. My definition: Full voice is the ideal vocal fold thickness (requiring perfect closure: not too tight and not loose) for a given tone. This fold posture requires a pre-requisite muscular balance in all the intrinsic and extrinsic muscles of the larynx and a dynamic muscular engagement that may involve every muscle in the body as support. How much breath pressure (subglottal pressure) this set up is able to sustain without fundamentally being altered determines how loud a singer should be able to sing. This explains why natural spinto sopranos of yesteryear considered Violetta and Lucia di Lamermoor necessary in their early careers. This explains why Pavarotti canceled Cavaradossi after Di Stefano mused that the role is a voice breaker if done too soon. Maestro Pavarotti in an interview in 1994 recounted the story and decided to put down the role of Cavaradossi for 14 years. When the muscles cannot handle increased pressure, the complex coordination that yields a balance between pressure and flow will be altered. Either the muscles will cause medial pressure to hold back the pressure (pressed voice resulting in thinning) or they will loosen to releave the pressure (loose phonation and heavy production). One or the other is experienced by young voices being asked to sing louder roles before they are ready. Increased volume requires increased breath pressure. I a balanced system, the pressure is translated to flow and sound pressure on the outside and remains stable. Nevertheless, the subglottal pressure must be increased to achieve greater flow when the system is balanced.
Not all singers are alike. Some singers are able to sing a slightly loose sound very loudly and then reduce fold mass and increase medial pressure as they reduce pressure and volume. This is a fine trick but it is not the kind of crescendo-diminuendo from pp to ff to pp that the early masters considered the confirmation of a proper technique. During this exercise, the full resonance of the tone must be experienced from the quietest volume through the loudest volume and back. This kind of skill is the pinnacle of vocal technique.
So to answer the question above, indeed the singer made a wrong assessment of the inability to crescendo to maximum possible volume. The voice could not grow further because the folds started to squeeze preventing further flow. The singer would have to cause a slight break by loosening the folds to be able to go further, but the presence of the voice would be lost from the resulting inefficiency of the tone. In short the singer was singing with a full fold posture that could only handle so much breath pressure before collapsing into a thinner or thicker set up. What is the solution?
The solution is patience and exercises that increase the strength of the correct set-up. Occlusion exercises are the best. But sometimes, it is worthwhile going to a slightly heavier sound to encourage the fullness of the setup if the tendency is to press. If the tendency is to thicken and loosen, then the opposite would work better. The more the singer uses the correct posture, the stronger it becomes and so with time it would be able to sustain higher pressure without being altered.
Not being able to sing a well-supported piano is a sign of a voice that needs to be further coordinated and balanced. That proper piano is the foundation for a great forte.
Hence, soft can be and in fact should be full. Therefore full is not necessarily loud. When a crescendo-diminuendo is done correctly, the folds remain in the same posture and it feels as if they are not involved and that the change in dynamic is a result of changes in the muscles of the body, responsible for breath-management. Hence, the throat in its balance activity feels passive. Ignoring imbalances in the throat and thinking that breathing alone will solve the problems is at best ill-advised and at worst simply uninformed.
Many singers do not have an adequate pianissimo and still manage great careers. Careers depend on many things other than ideal vocal balance. That however is for another discussion already addressed in the previous post.