When many voice experts refer to the "passaggio", they are commenting on the last bridge before entering the high voice; e,f, and g. This concept is applied for roughly all their lower or higher voiced singers. I was taught in my vocal pedagogy class, that there are two passaggi, a primary and secondary passaggio. I have found it interesting that the relationship could actually have some bearing on the concepts of developing the voice and is representative of the way the voice really works. It has brought me to what I think are interesting conclusions. For instance, how to dependably tell whether a student is a tenor or a baritone, or soprano or alto. Many singers after years are still wondering about whether they are a this (low) or a that (high) vocally. Understanding the passaggi in the voice can completely draw definte and applicable lines of determining the voice part or fach of a given singer.
To make application you have to accept the concept of the thyro-arytenoids as behaving like a vibrating string; having nodes, and harmonic interplay based on the frequency or pitch/mass relationship and the cavities of the human body (thoracic, laryngeal, pharyngeal and sinusoidal). With the help of the crico-thyroids, our voices are capable of producing all pitches in our 3 to 5 octave ranges. In light of this, every voice has natural weak points based on genes and ones particular body type. This in combination of the individual's genetics as worked out through the vocal cords add to these varieties. Take for instance the varying lengths of peoples necks, how tall or how long or short waist-ed, or how low might ones larynx seat, the size of tongue; the width of the cheek must affect the interior dimensions of the pharyngeal spaces. All of these variations make up the individual voice of ones particular whole body. Based on all of these variances, and in combination with the size and thickness of the vocal chords, the voice will develop around its own string behavior and harmonics, causing a weak spot that will coincide with a particular pitch in the middle of the voice; the lower passaggio, This naturally weakened pitch is the fulcrum of the individual voice's harmonics, it behaves in an unpredictable way due to its uniqueness. It is sort of like a node on a vibrating string (not to be confused with the vocal malady, I refer to the point on a string where a violinist or guitarist gently rests their finger to access the harmonic series of the instrument). This string behavior in my opinion has bearing on how the voice effortlessly moves from pitch to pitch, and shifts octaves and registers with speed and accuracy.
If you are a baritone, and this note is b flat, you are a bass-baritone, or a mezzo-soprano if female. One whole step higher and you have spinto tenore, and soprano dramatica, both exhibiting a break at a c sharp in the middle. This application is obvious. A flat; contralto, or basso profundo, A natural; lyric bass, and alto, B flat; bass-baritone, dramatic mezzo soprano, B natural; mezzo or baritone, C; lyric baritone, lyric mezzo, C sharp; spinto soprano/tenor, or dramatic (some may believe their is a distinction between the two), D Lyric Soprano/Tenor, D; E flat; Coloratura/ Leggiero, and so forth, we have all varieties of coloraturi.
A-flat ; basso, contralto
A natural; lyric bass, alto
B-flat; bass baritone, mezzo
B natural; baritone, mezzo/lyric mezzo
C lyric baritone, lyric mezzo
C-sharp; dramatic tenor, dramatic soprano
D; lyric tenor, lyric soprano
E-flat; leggiero, dramatic coloratura
E; leggiero, coloratura
This is all very tedious to attempt writing or to say the least to read, but its dependability is very helpful as teachers search out the proper voice classification for their students; especially if you teach young developing singers. The primary passaggio is not easily found until the leverage of diaphragmatic pressure against the voice is completely eliminated. If the note is pressed or over-blown it will negatively impact the development of the vocal cords at this juncture buy distorting the natural flexing of an undeveloped but registration that now presents itself in voice of an adult or adolescent singer.
This is the case with most singers; as it is a note low enough to dependably hit. It is then often used as a leverage point for the upper voice and never quite working as a dependable means of getting across the secondary passagio that is exactly a perfect 4th above the primary. Abdominal breath pressure disguises this fulcrum note that is an individuals lower passagio, or the primary passagio. Diaphragmatic leverage creates too much air pressure and will develop into an overly thickened primary passage as it develops into a mixed registration, as coined by the late Cornelius Reid, God rest his soul. Once properly exposed and isolated, and while the student learns to not crescendo to ascend the scale (using to much diaphragmatic leverage), you will begin to notice that the perfect fourths above and below the lower passagio, have similar characteristics that create an inconsistent scale (even natural sound that has an unchanging tone thought out the full range), a note that is fuzzy. The student will usually press this "easy to get to" note to try to overcome its natural dullness, (which is why diaphragmatic pressure is so sinister, it makes the not feel a more secure but simultaneously distorts the harmonics of the singers instrument. The incorrect gesture will dig in and will require serious and tedious work to overcome. Even with no inappropriate pressure on the voice the primary break is difficult for singers to keep on pitch, it is a little slippery in both directions, it is like the vocal continental divide the sound wants to slip to either side up or down. Causing cracks and sharping of pitch while it releases too much air or causing flatness of pitch or muddiness of sound and rhythm.
These passagi throughout ones range and exist as divisions in the voice that are in perfect fourths. They behave largely the same way. The half step above the break is breathy or falsetto(y), the passagio itself is slippery and weak in fundemental or fuzzy, the half step below is too chesty and weighty.
To develop these weak notes I use spoken sounds as glottal strokes (no diaphragmatic support at all, as if spoken casually). A student of mine will sing the letters of the vowel series. Singing as if speaking the vowels as letters a, e,i o, and u. What singing vowel sounds are these? (a) Day, may, spade, (e)see me the eve, Lee. (i) My by Thai spy, (o) go know stove grove, (u) you Sue,too blue.
With unpressed development the natural huskiness of the primary passaggio begins to grow amber; and make the voice drip deep dark honey, because its middle note is vibrating intensely while not being pressed has been strengthened to bright fundamental that is hyper efficient and wastes no air. This perfect equilibrium allows the vocal cords to vibrate like a string in the balance of poised physics. It is optimized because of the dynamic play of tension and relaxation as the vocal folds vibrate in tone-breath flow loop of something similar to a cat's purr. This is when you can know what proper breath support is, the Italians called it appoggiare You just lean gently on and pulse this vibrating tone loop that is in balance between your vocal cords and the top of the diaphragm. Wild vocal power is accessible while hardly having to stir the body. All registers are accessible with perfect ease; wildly variant timbres are instantly brought into the tone. The singer learns not to get louder to go higher unless the dynamics call for it. You simply excite the harmonics. Then the overtone harmonics of the voice begin to present themselves and strengthen the sympathetic ressonance of the variant register of ones voice. This perceptible harmonics of octaves, dominants, the thirds, drawn off the fundamental pitch. Rather like the variable registrations of a pipe organ. The human voice, properly trained, has massive power and flexibility, unique faceted beauty of tone with breadth, volume, and perfect intonation.
Working these concepts out will give you full control of your voice allowing you to play the voice like a trumpet in three octaves on any vowel sound (no modification whatsoever). You will also have dazzling vocal power; a very clear light tone to ppp while still being clearly understood and present in any hall; agility; and vocal freshness after performing.
If you get through all of this, your a real trooper.