To my knowledge, there is no greater exercise for the human voice than that of the messa di voce. This swelling and diminishing of the tone lays bare all imperfections of the voice. A voice that cannot swell and diminish fluidly has not achieved functional balance, and regardless of the size of the instrument – or the size of the career – the messa di voce is the Great Equalizer. It is the KING of all exercise for the voice.

An author who wrote on the messa di voce was Alexis de Garaudé.  He was a French composer and educator who led the voice department at the Paris Conservatoire at the beginning of the 19th century. It must be mentioned that Garaudé was also the pupil of the celebrated castrato Girolamo Crescentini.

Garaudé described the practice of the messa di voce:

The Scales of messa di voce sound [that is, each note of the scale having its own messa di voce] are the most useful exercises for singing well. One can never apply too much care to them. They work to perfect the vocal organ and to make the voice flexible for all the intentions of taste and expression.

To work such a Scale, the Pupil will ensure that his or her mouth is in a natural position, smiling and open in the manner most suitable to its particular conformation….You will then attack the sound with quickness and accuracy, without approaching the note from below, and without any breath noise – indeed you must economise the breath to make it last as long as possible.

Each sound of this Scale will be made on the vowel A or open E, and it must be spun; that is to say that it must be started very soft, then gradually increased until halfway through the note (where it reaches its greatest strength), then imperceptibly diminished until the end of the note.

This manner of spinning the sounds is called mise de voix (messa di voce).

Garaudé then goes on to describe the particular care that one must bring to this work of messa di voce:

In doing this Exercise, you must be careful to emit the sound of the voice with purity and without effort. In that strengthening of the middle of the spun note, you need to give it the maximum development you can, but without ever altering your vocal organs to the stage where they would force or squash the sound. The quality of your timbre must retain its natural sonority, and the intensity must follow all the artistic rules we have previously described. Please also note that the decrescendo of the spun note must be as long as the crescendo which starts it.

As soft as the start and end may have been, your Register must throughout be the one that you use for your loudness halfway through the note. Many pupils make the mistake of letting every decrescendo of the note degenerate into head voice – but that is only applicable for the high notes.

Soprano Clara Doria put on guard any singers who would attempt this with muscular control:

Singers often think they are making a ‘crescendo’ when in fact they are doing nothing of the kind. This is when they press on some of the throat muscles in their ignorance of how a crescendo is made, and associate the physical pressure with an increase in volume of sound. They do not really hear an increase in sound, but they take it for granted that there must be one in response to the pressure, which pressure, in point of fact, simply hardens the tone, or renders it tremulous – sometimes both.

With her next statement, perhaps we see why so few singers and teachers, who are so breath-obsessed, are able to manage even a moderate execution of the messa di voce:

The most important thing in swelling the voice is the freedom of the muscles controlling the breath. The singer…should only be concerned with pitching, swelling, and diminishing the tone itself, without regarding how it is done or what does it.