High pitch, high volume, high intensity, high urgency.... this is a shout! Singing is just a fancy illusion which disguises our rather primitive, acoustically inefficient instrument into something other worldly. This is done by manipulating "registers," vocal tract configurations, vowels, formants, vocal fold tension, etc.
I believe the voice has modes or what some classical systems might refer to as registers. The sort of.. "pulled chest" sound I believe is a vocal mode or vocal register. The system Complete Vocal Technique (CVI) designed by Catherine Sadolin refers to this mode as "Overdrive."
This "pulled chest" sound is probably what you associate most with shouting =). Roberto Alagna uses this mode of the voice. Some might he is too shouty.. but I adore him!
Pavarotti, though, makes a transition into a different mode/register as he sings. Some might say he "thins out" or twangs a bit more to release fold tension. In the voice system Complete Vocal Technique (CVT) this is called "Edge." In this clip Pavarotti is attempting to guide his student toward this mode of the voice. He uses words like make the voice smaller, makes a "quacky" sound, compares the voice to a trumpet, makes a grimmacy toothy face suggesting a more forward placement, and so on.
The student gets close... but, ultimately, does not succeed. Instead, he holds onto the "weight" of overdrive. Better luck next time!
What makes singing so difficult, then? Our voice was not designed for singing it was designed for survival. The pitches above speech-level are not supposed to be sung... these notes are in the "calling" part of our voice (unless we are in falsetto/M2.) A skilled singer can manipulate this "call" into a wide variety of different sounds, timbres, intensities... but that does not change, fundamentally, what the singer is doing!
The "yelling" element of the voice is often overlooked. And it's done for good reason. It's very, very easy to misinterpret. Teachers will misunderstand... students will misunderstand. It's a risky concept.. but it's a really important one! If you're reading this blog you have enough common sense to know when you've gone too far! Most of you, however, are not going far enough.
Take Pavarotti's word for it! "[The voice of the tenor] is very exciting because it's very dangerous... and you feel it."