Squillo, which is sometimes defined “as that piercing resonance” has nothing to do with the Singer’s Formant. Singer’s Formant does not give the voice its brightness. For example, Bjorling’s voice has seldom been classified as being as bright as Corelli yet his voice has more Singer’s Formant than does Corelli, and Corelli’s is substantial.
The Singer’s Formant is created in the aryepiglottic space immediately above the vocal folds before the phonated sound enters the primary resonance spaces of the pharynx and mouth. As such it is not affected by vowel changes. All vowels are created by resonance changes in the pharynx and mouth and the primary control of vowel identity is the position of the tongue within these spaces.
Singer’s Formant has little to do with vocal size. Vocal size is a factor of resonance balance below the harmonic range of the Singer’s Formant. A dark quality is achieved by emphasis on lower harmonics of the sung tone. A bright quality is achieved by emphasis on higher harmonics of the sung tone. And the ideal goal is a good balance between the bright and the dark qualities, the desired “chiaroscuro’. Yet all of these harmonics are below the 2800 to 3200 Hz range of the Singer’s Formant.
Surprisingly little breath is required to produce an amazingly loud sung tone. Size, or volume of lungs has little to do with it. Breath pressure does. And breath pressure is controlled by both the exhaling muscles and the time that the vocal folds are closed during each oscillating cycle. The ideal is to have the folds closed about 40 to 60 percent of the time during each cycle. At A=440 the vocal folds open and close 400 times (cycles) per second. And during each cycle the folds should be closed for about 50 % of that cycle. This provides the resistance to the breath necessary for healthy phonation. If the folds are closed for only 30% of the cycle, breath pressure is reduced and the tone has a breathy quality. If the folds are closed as much as 75% of each cycle breath pressure is greatly increased and the tone has a tight, pressed quality. Most singers move between these ranges depending on the emotional and dramatic needs of the music but the fine lyric connection of sound so desired in classical sing and opera is sustained by the 50% closure rate.
A small voice with Singer’s Formant will be heard through any kind of orchestral sound but that voice will still sound like a small voice. A large voice without Singer’s Formant will easily be covered up by the orchestra even though the voice is large. The reason for this is that the Orchestra has its loudest harmonic emphasis at around 500 Hz and the Singer’s Formant, at about 3000 Hz, is located sonically where the orchestra sound is become much weaker.
Singer’s Formant is a learned thing. Some may learn it quickly and others more slowly but is is learned and taught. It requires that the space immediately above the vocal folds be widened and the larynx be kept at a slightly lowered position to properly adjust the aryepiglottal space to achieve this resonance.