We frequently hear agreeable tones, as far as musical quality is concerned, but we have, in nine such cases out of ten, to dispense with a clearly defined vowel, as, in order to obtain the musical quality, the singer generally sacrifices, or distorts, the vowel, so that it might be anything but that which it is in tended to be.
This fault has been tacitly encouraged by many teachers, owing, I think, to attention having been called by laryngoscopists to the change which takes place in the shape of the vowel forms, to reenforce properly the different pitches of tone. A misunderstanding of this theory in its practical application has been made an excuse for slovenly pronunciation. To alter or distort the sound of the vowel in order to favor the resonance of the tone is working quite in the wrong direction, — it is robbing Peter to pay Paul.
The theory of altered vowels would not, however, have worked the harm it has done if it had been accompanied with the counterbalancing law that, what ever physiological changes may have to take place to furnish a resonant and musical sound on certain combinations of pitch and vowel, the clearness and distinctness of the vowel sound to the ear must at all costs be maintained.
Rogers, Clara Kathleen. My Voice and I: Or, The Relation of the Singer to the Song. AC McClurg & Company, 1910.
David Ffrançon-Davies was a Welsh baritone and regarded as an authority on the voice. He studied under the tenor William Shakespeare, who himself was a student of Francesco Lamperti. In his book The Singing of the Future, he mentions an issue for students that strive to acquire resonance:
A very vital danger confronts the student at the start, viz., the danger of securing resonance rapidly at all costs. This resonance is often procured by an unnatural and distorted raising of the palates, and a forcible downward pressure of the root of the tongue. All such fictitious and forced methods of securing ready-made vocal vesture cannot be too strongly condemned. The texture of the voice must be slowly woven in the loom of time. It is wise to look upon the voice as an instrument, wiser to spend years in perfecting it technically, wisest to add to this the discipline of soul and intellect, so that the song which flows through that instrument shall possess all the qualities which go to make a great personality. The pursuit of technique, or mastery over the voice, will prove to be an intellectual and spiritual discipline, provided it be approached in the proper spirit.
“The modern voice induces and applies resonance by means of a forward production independent of the pitch of the note to obtain a predetermined ideal resonance not naturally appropriate to the note. Certain exercises stimulate supposed places of resonance, thereby working on the effect and not the cause of sound production, in other words putting the cart before the horse. The result is that you sing with the voice that is predetermined and now in fashionable demand, not, however, your own individual voice, which was the fashion for several hundred years. Blanche Arral illustrates this very clearly remembering the great voices she heard in her day:
Each of these voices had a color which was peculiar to it. One voice might be said to be golden, another silver, one a brilliant vermillion, one a rich dark purple. There was a wide variety in texture, color, and tone, and I attribute all this to the method of emission of which I have spoken…To my ears most of the young singers I hear now possess what we would have called in my youth la voix blanche. This means, as well as I can describe it, a voice lacking in musical ring, lacking overtones, as they are called now, in fact having very little true tone any any sort – colorless, flat, artificial, and far from the genuine article, the true natural quality, for few voices are naturally white.
We see that Arral knows exactly why voices in 1937 sounded different compared to the voices she used to hear from her colleagues when she mentions the “method of emission” as the cause of good or bad vocal sound. A quarter-century later Herbert-Caesari completely agreed with Arral condemning the modern “method of emission” in no uncertain terms: “The so-called ‘forward production’ method is largely responsible for the general low standard of singing, technically speaking, and for the ruin of innumerable voices. Its history is inglorious. It is invariably wedded to that obsession: Diaphramatic drive. The nefarious marriage has wrought untold harm.”
Bloem-Hubatka, Daniela. The Old Italian School of Singing: A Theoretical and Practical Guide. McFarland, 2012.