Recently on “Vocalist” an important question was asked about the location of female and male first (primo) passaggio:
I’m confused! Why does the primo passaggio point in female voices lie lower as the voice gets lighter (Eb4 in sopranos, E4/F4 in mezzo-sopranos and G4 in contraltos) whereas the corresponding case in male voices is quite contrary (primo passaggio is higher as the voice gets lighter)?
This is not too difficult to answer but it is problematic to use terms that are not ambiguous. The explanation for female voices is different from that for male voices even though the female first (primo) passaggio is in about the same position as the male single passaggio. The female voice has a second (secondo) passaggio about an octave higher than their first passaggio. The male voice has no second passaggio.
FOR FEMALE VOICES
Since you use the word lighter, I will used the word “heavier” to describe mezzos and contraltos.
A lighter voice will have a lighter middle voice and a lighter middle voice makes it easier to extend the middle range down to about Eb4 or even D4 while still keeping a timbre similar to the rest of the middle range.
A heavier voice will have a heavier middle voice and the darker quality of that voice tends to go into chest voice at pitches that are higher than the D4 of the lighter voice. You state pitches of about E4 to F4 for mezzos and even as high as G4 for contraltos. I have observed this to be true.
Another way of saying this is that the heavier, darker voices have a greater chest voice range than those of lighter, brighter voices. Of course it is possible for the heavier voice to sing more lightly in the middle range and, by doing so, to extend the middle range downward a note or two lower than usual. However, one of the desirable characteristics of a heavier voice is its darker middle voice so to lighten that voice quality is counterproductive.
Keep in mind that all of the above is true only if the voice is singing an /a/ vowel. All passaggi are moved slightly up or down depending on the vowel being sung. It is the position of the first formant that is the primary factor in the location of the passaggio. The vowel /a/ has the highest first formant; it rests just below the second formant which is lower in this vowel. This keeps the relative position of the passaggio as you have described it.
The /i/ and /u/ vowels have the lowest first formants and this allows the singer to carry the middle voice a step or even 2 steps lower before having to go into chest voice. This provides the lowest position of the female primo passaggio as per each voice type.
The /e/ and /o/ vowels have first formants that are slightly higher, somewhere between the high first formant of the /a/ vowel and the low first formants of the /i/ and /u/ vowels. Consequently, the /e/ and /o/ vowels will lower the primo passaggio but not as much as occurs with the /i/ and /u/ vowels
An example exercise that I sometimes use to make the singer aware of the effect of vowels on passaggi is to have the singer sing an /a/ vowel on a descending diatonic scale beginning somewhere near the top of the middle voice and change to an /i/ vowel a few notes before the usual switch into chest voice would occur. The most common effect is the singer is able to sing the new /i/ vowel down almost a minor third lower and then slip easily into chest voice with no apparent passaggio shift. The /i/ vowel has lowered the change point of the primo passaggio.
FOR MALE VOICES
In general terms, the male voice sings an octave or more below the lowest notes of the comparative female voice range. The male voice sings in either chest voice or head voice. It has no middle voice. The chest voice for male singers is the largest portion of their voice extending, depending on voice type, from C2 (or even F1) for lowest basses up to F4 or G4 for tenors. A range of three octaves of chest voice for the male voice collective. Since there is no middle voice, the male voice must change not only his vocal fold thickness as he sings higher but, to extend his voice above the chest voice limitations, he must also change his resonance strategy. In chest voice he is tuning his first vowel formant to the second or third harmonic. At the passaggio, he must tune his second vowel formant to third or fourth harmonic. This produces a definitive difference in vocal color and many men speak of it as the voice “turning over” or “lifting” and other such terms. This is not falsetto, but a strong, vigorous vocal tone that easily soars over a full orchestral accompaniment.
The passaggi of male voices are higher for lighter voice and lower for heavier voices because the chest voices for these voice types extend higher or less high. The tenor can extend his chest voice up to F4 or even G4. A baritone has a chest voice that usually ends at about D4 or Eb4. A bass finds any note above Bb3 or C4 very difficult to achieve in chest voice. Once the chest voice reaches its upper limits it must no longer be using the first formant as the primary resonator. It must switch to the second formant and that provides an extension of the vocal range beyond the upper limit of the chest voice. This is the classic form of male head voice. Second formant tuning produces a standing wave within the vocal tract that provides, as it were, a pneumatic cushion for the vocal folds and the exchange of energy from the vocal folds to the air is greatly increased thus reducing the strain on the vocal folds while, simultaneously producing a substantial increase in sound amplitude.