After voice has originated within the restricted limits of the larynx, its power, its carrying quality is much augmented by the sympathetic vibrations within the resonance cavities above the larynx. These include the pharynx, nasal passages, mouth, bone cavities of the face--in fact pretty much every hollow space in the head, every space that will resound in response to vibration and assist in multiplying it. Moreover, the cavities of resonance by their differences in shape in different individuals determine the timbre or quality of individual voices. The chest, although situated below the larynx, is a resonance cavity of voice. In fact, in a certain register its vibration is felt so distinctly that we speak of these notes as being sung in the "chest register," which, so far as it implies that the tones are produced in the chest, is a misnomer. The same is true of "head register," in which vibration is felt in the head where, however, it is needless to say, the "head tones" do not originate. Expiration--breath-emission--is the motor function of the vocal organs; and there are two other physical functions of the organs--vibratory and resonant. Added to these is the sensory function, to which I attach great importance; and I call it a psychological function because it acts through the nerves upon the physical organs of voice. Without it the three physical functions--motor, vibratory and resonant combined--would remain ineffectual. They could generate voice, but it would be voice lacking those higher qualities that are summed up in the word "artistic." It would be a physical, not an art product, a product generated by the body without the coöperation of the mind or soul. When it is considered that the larynx, in which the vocal cords are situated, is permeated by a network of muscles through which it is capable of some 16,000 adjustments and readjustments of shape, all of them pertinent to voice-production, and that the same thing also is true of the pliable portions of the resonance cavities; that these muscles act in response to an even finer network of nervous filament; and that the constant shaping and reshaping of various parts of the vocal tract during voice-emission is directed by messages from the mind, soul, or art-sense of the singer, messages which travel via nerve to muscle--the only route by which they can travel--it becomes possible to appreciate the importance of the sensory or psychological function which, I hold, should be added to the purely physical ones of motor, vibration and resonance. For by it these functions are enlisted in the service of art and made immediately and exquisitely responsive to the emotional exaltation of music and song. Nor are these vague terms. Psychology of song and psychological action in general may seem indefinite and unintelligible. They become, however, absolutely definite and intelligible when the part played by the nerves as intermediaries