The art of singing is, in spite of the great progress we have made in science, still based on empiricism.

Originally the old Italians built up the whole art upon it; and only in our time has it received a more scientific foundation through Helmholtz, and especially in his 'Vocal Theory." ....Even Laryngoscopy has hitherto been of very little use in the development of the vocal art, as the formation of tone cannot be properly taught by its means; observations on the vocal chords can only be made on the vowel ae, and then it is necessary to have a foreign body in the mouth. The formation of tone under such conditions is too mechanical, and is indeed unnatural; the higher intellectual conception of tone is wanting. But the tone ought to be noble, poetical, and animated, and to be produced through inspiration, as only thus can we do justice to the art of singing.

It is unwise to break with our empirical traditions, and to look down upon the old Italians with disregard, as to overlook the progress which the art of singing has made through science. We must, however, not overestimate the latter. Let us go impartially through the different sciences, examine and investigate how far they are of practical use in the art of singing, and then we shall find that empiricism must always help us in our studies.

Hypotheses which have repeatedly served to explain certain phenomena are considered laws, but they cannot permanently have the necessary authority, and are displaced by higher hypotheses. It is indeed a wise ordinance of Nature that without mechanical instruments we cannot see the working of our voice apparatus, and we can only feel what we produce with it; for, after all, Art is entirely an outcome of Feeling.

The most important thing in the art of singing—I mean the colour of tone—cannot be described; we must hear good and cultivated singers, and they must in our studies enlighten us, and be our ideals. If the teacher be only a good musician, and not at the same time a good singer, the proper study of tone-formation is out of the question. It is such teachers that we have to thank for the new but false theories—that the learned ought to begin the tone-formation with the vowel u, and that there are five registers to equalize the human voice.

The excellent results we have obtained by the old method, in which Jenny Lind, Adelina Patti, Albani, Santley, Sims Revves, Lloyd, Lasalle, and others have been instructed, prove that, we should still cultivate and honor the old method, and adopt from the new only what is good and useful.

The vowel a (ah) is and remains forever the king of vowels; poor u has, after a service of centuries, not reached the position of a chamberlain, since it still fills, literally as well as figuratively, only the humble function of a "door-closer."

As to the registers, I will here only say that in some voices we observe feeble notes, which sound weak and contrast greatly with their stronger neighborly notes. Such, like all uncultivated voices, we can equalize by the true Old Method, which consists of piano singing.

In our studies we must never leave the ground of experience, and lose ourselves in speculations. The scientific foundations of singing—namely, acoustics, physiology, and anatomy—I have not fully treated, confining myself to such an exposition of them as I consider to be useful for the singer and musician. The ear, however, I have treated with particular care, as it is well known to be the best guide and teacher in our studies.

—Albert B. Bach, The Principles of Singing: a Practical Guide for Vocalists (1885): xi-xv.

The traditions of the old Italian schools have been bequeathed to Caselli, Aprili, Bordogni, Ronconi, Concone, Marchesi, García, Lamperti, Varesi, G. Engel, Seiber, Stockhausen, &c. All these masters taught, and some still teach, the old Italian method; but it is no longer Italy alone that teaches good singing. Every country has some intelligent teachers who are singers, and who have accepted and studied the old Italian method; and every town should have such masters, as these only can foster and further true vocal art.

—Albert B. Bach, The Principles of Singing: a Practical Guide for Vocalists(1885): 95.

Albert Bernard Bach (1844-1912), Hungarian baritone and author. He was born at Gyula and studied under Marchesi at the Vienna Conservatory in 1869-70, and later with Cunio, Weiss, and Gansbacher. He gave his first concert as a bass-baritone in Vienna. Later he studied in Milan (1876-77) under Lamperti, Ronconi, and Varesi, and sang at La Scala in 1877-78. He taught in Britain and German after 1886, and also sang there in oratorio and concert.

—Brian Tyson, Bernard Shaw's Book Reviews (2008), Vol 1: 117.

Art is entirely an outcome of Feeling. 

So wrote Albert B. Bach, and I could not agree more. This is literally true from the perspective of Alfred A. Tomatis, who observed that the vestibule of the ear regulates the feeling of the body within space. As such, singing is not only a matter of emotional feeling, but also physical feeling. To sing—and to sing well—the body must feel extended, lifted up, and innervated—even if you are singing the blues. These feelings, which Tomatis understood as the product of an open ear, was understood by old school voice teachers as the

Singer's Sensation, and was discovered and refined through inhalation through the nose with the mouth closed or only very slightly open. You know you are finding your way forward when you can feel the muscles of your head move; and when these muscles move and are maintained from the get-go—rather than after 10 or 12 seconds of inhalation—every vocal technique will be within your reach, including the messa di voce, mezza voce, staccato, trill and coup de glotte of García.