It has already been many times urged that when breathing is satisfactory, breath does not escape to any considerable extent into the mouth cavity, but that the expiratory blast is used to set the air of the resonance-chambers into vibration. The changes that must be made in these cavities, to lead to certain effects, are accompanied by characteristic sensations, and these, and not the direction of the breath, are largely responsible for the ideas on which the above expressions rest. As before shown, the soft palate is constantly being used more or less, and when it and the tongue unite in action so as to cut off the mouth cavity, or, more strictly, the anterior portion of it, from the nasal chambers, a very pronounced modification in the tone results, and, of necessity, such actual escape of breath as occurs takes place through the nose. In reality, there is a special modification of the shape of the resonance-chambers for every tone produced, and especially when the color or quality is changed, as well as the pitch. There is, therefore, not only "forward" and "backward" but also middle production, though, in reality, these terms at best but imperfectly describe, even for practical purposes, what happens. It is to be feared that with some teachers of both singing and speaking "forward production" has become a sort of panacea for all vocal ills; but it is not, and just the reverse teaching is required in certain cases. If a voice be brilliant, yet hard, it will be improved by a more backward production, judiciously employed, and in this way the French language is often to be recommended to such singers, as it favors this backward production, with such use of the nasal resonance as mellows the tones. The tenor who has not learned the use of the nasal resonance, to give richness to the tones of his middle and upper range, has missed a valuable principle. On the other hand, for voices that are too soft, lack brightness, and fail in carrying-power, a more forward production will often improve the quality of the voice greatly. But a little consideration must convince the student that if he is to be master of his voice-production throughout, if he is to produce tones of every shade of quality, he must be able to shift that voice about in every quarter as occasion demands; in other words, _all the changes possible in the resonance-chambers must be at his command_. Such is the case in the very greatest singers of both sexes; and, of course, this applies equally, if not still more, to speakers.