“From beginning to end of voice production the tone concept is the only guide. Every one knows what satisfies his ear, but his ear is his musical taste, and musical taste is by no means definite and fixed quantity. One’s taste marks his stage of development, and if he be studious it is constantly changing.
In developing the voice the most important part of the teacher’s work is that of forming the pupil’s taste in tone quality. In other words it is forming the tone concept. Either through explanation or example the pupil must learn that the singing tone is smooth, mellow, rich, resonant, and sympathetic. Also that good tone is always easily produced. It is the bad tone that is difficult.
Throughout the work of forming the voice the pupil must not be allowed to forget that the tone is the thing, and that how it sounds is his primary concern.
Most vocal students think there must be some conscious physical effort in tone production, and as result they almost invariably over do it and thereby offer resistance at the throat which not only makes the tone difficult of production, but greatly impairs its quality. There is practically no conscious effort in the rightly produced tone, hence it follows that next to the tone concept the most important thing is having the conditions such that the ideal tone may be perfectly expressed.”
Clippinger, David Alva. Systematic voice training. Gamble Hinged Music, 1910.