Pedro de Alcantara is a cellist, Alexander Technique practitioner and writer, whose book Integrated Practice has been one of my favorite recent reads. It is a book that I will keep handy as there is a lot of great information in it, and it is applicable to all kinds of music making.
In his book, he lays out a great overview of the mechanics of the vocal registers within the context of the Old Italian messa di voce exercise.
The point where one register’s pitch range ends and the other starts is called the break. Its location is variable depending on the condition of your voice and how you use it, but it lies (for women as well as men) in a compass of several semitones around E above middle C. Example 19.2 (shown below) is a schema established by Cornelius L. Reid, showing the registers, their respective pitch range, and the vowel and dynamic scope most likely to trigger their innate qualities.
Let’s call the registers’ basic actions pulling and holding. One register holds its ground, and the other pulls against it, in an elastic and ever-changing opposition of forces. As you pass from note to note, from vowel to vowel, and from forte to piano and back again, the registers’ interplay of pulling and holding changes constantly.
Sing a note on the vowel “ah.” While holding the pitch, change the vowel to “ee.” This will alter the balance between the two registers in some way. Sing a low note on the vowel “ah,” and pass to a note an octave above on the vowel “ee.” The balance of registration will change more significantly. Sing a note on the vowel “ee” right around the break – on an F, for instance. Make it swell and diminish. You’ll use a certain register balance singing quietly and another balance singing loudly, making the falsetto and the chest voice dialogue and collaborate. The art of vocal registration is subtle and difficult, and it’d take a whole other book to lay it out in detail. What we can state unequivocally is that it’s not possible to be a good singer without a good control of the messa di voce.
In advanced stages of training, Reid writes,
the performance of the messa di voce must be practiced continually until there is an exact matching of both the quality and intensity at the point of transition. After this technique has been mastered the “break” disappears, and the singer is able to pass freely from one register to the other, from soft to loud and from loud to soft, without difficulty…This is the singing style known as Bel Canto.
Example 19.3 is another schema established by Reid. It illustrates the collaboration between the registers and its result upon the vocal range.
When performed in the manner Reid advocates, the messa di voce is the ultimate voice-building exercise. It isn’t the only way in which singers can use the messa di voce, since in the vocal repertoire there exist limitless possibilities for swelling and diminishing tones that lie comfortably away from the break between the registers. In other words, singers can practice the messa di voce on all notes, but when they practice it on certain pitches and vowels, they’re using it in a singularly rewarding manner.
Do this for a few days and weeks, and undoubtedly you’ll see, hear, and feel wonderful results. But do it for years and the results will be dramatic. You don’t even have to devote yourself to the messa di voce out of duty; you can do it wholly out of pleasure. The vibrations of your instrument or voice when you perform a good messa di voce make daily practice a treat, not an obligation. Start every practice session with variations on the messa di voce, and you’ll always look forward to practicing, day after day, for the rest of your life.
De Alcantara, Pedro. Integrated practice: coordination, rhythm, & sound. Oxford University Press, 2011.