Training of the organs of speech has been written upon so extensively that for now more need not be said.

Suffice it to say, that the organs of speech can be trained upon a few enunciator syllables in a short time, so that every word can be distinctly understood. There is no excuse whatever for our singers remaining os indistinct in their singing. The way of getting the tone to agree with the words, is what may be considered now. As said above, tone is regulated, so far as quality goes, in the pharynx. That organ can be put into working order and kept so through the expression of the face. The same thought is expressed on the throat which is expressed in the face. The same set of nerves operates the two organs. To show what is meant, recall that if you hear someone utter a cry, you know from its sound whether it is a cry of fright, or happiness, or fear, of greeting, of anger, or whatever it may be. The position and shape of the pharynx has made the cry what it is. One standing near the person would see on his face the look which corresponds with the cry uttered. In this case the word and the tone correspond. It is not easy to reach the pharynx for voice culture, except though the face. It can be reached in that way. The tone for general use in voice culture should be the bright one. Then the expression during vocal practice should be a bright one. All vocal exercises should be, on this account, practiced with the face pleasant and expressing happiness. This face led many teachers, years ago, to have their pupils smile while singing. It led to most ludicrous results. The teachers said, "Draw back the corners of the mouth, as if smiling." Very well. That may be good, but has no particular beneficial influence on the pharynx, or upon the tone produced. The mouth is not the seat of expression in the face. Not that there is no expression in the mouth, but its changes are limited. The eyes are much more thoroughly the seat of expression, and through them the pharynx can be reached. Let the eyes smile. Let the whole face take position as if one saw something irresistibly funny, at which he must laugh. Practice with the eyes in this way will brighten the whole voice. It will relieve strain upon all the facial muscles and will render the organs of speech more pliable too. Having obtained such control of the use that one expression can be placed in them, the student can attempt other desirable expressions. He will find that whatever is used in and about the eyes will affect the kind and quality of tone. He may arouse his interest in some particular thought and hold that in mind as he sings; the voice will then have warmth of tone and will readily receive meanings. He may express varying degrees of surprise in the face and he will find varying degrees, to correspond, of fulness and roundness go into the voice. The use of expression in the face as a means of giving character and quality to tone opens a field of experiment and experience which will lead any teacher to practical and beneficial result. It is not a new idea. Salvini,the great actor, has given some very useful thought on that subject. Little of such instruction, important as it is, has gone into print. Yet it is so important. 

—Frank Herbert Tubbs. Seed Thoughts for Singers, 897: 106-108

It is still important, and still largely ignored and written about. The only modern person known to this writer to address the matter of the eyes, face and voice is Alfed A. Tomatis, who observed in The Ear and the Voice that the facial nerve inserts into the inner ear via the stapedius muscle. As such, the singer's listening ability can be readily observed. Why is this so hard to comprehend? Because too many singers and voice teachers look but do not see, and while in possession of the physiological function of hearing, do not yet know how to listen—which is a skill that can be learned.

Seed Thoughts for Singers is Tubbs' only text currently available for download, and is well worth your time and attention. As a student of Manuel García and Francesco Lamperti, Tubbs can be observed to have given the reader something of their teaching. 

Photo Credit: Frank Herbert Tubbs c. 1890's, New York Public Library