There is a difference between the natural and the properly trained voice. As to the nature of this difference the facts of empirical observation are borne out by the results of scientific analysis. The natural voice is crude because it is unskilfully used. A lack of facility is revealed in the untrained singer's handling of the voice. Intonations are imperfect; transitions from note to note are rough; the whole effect indicates that the voice is not completely under the command of the singer. Further, the sound of the individual tones betrays faults of production. The tones are more or less throaty or nasal, or indicative of some degree of muscular tension. A perfectly used voice, on the other hand, convinces the hearer that the singer has full command of all the resources of the vocal organs. Each tone is a perfect musical sound, free from fault or blemish. The voice moves from one note to another with ease and with purity of intonation. All the gradations of loud and soft, all the lights and shades of sentiment or passion, seem to respond directly to the singer's instinctive desire for musical expression. On the physical side the singer's voice is felt by the hearer to be in a condition of balanced and harmonious muscular activity. When the possessor of a good natural voice goes through a proper course of vocal training, the faults of production native to the untrained voice are gradually corrected. Wrong muscular tension is imperceptibly relaxed. Little by little the student acquires facility in handling the voice. Coincident with this progress is the advance toward the correct vocal action. The transition from the natural to the perfect use of the voice is gradual and imperceptible. There is no stage of progress at which the operations of the voice radically change in character. At no time does the student change the manner of managing the voice. Effects difficult at first gradually become easier, simply as the result of practice. This is the only change that the voice undergoes in training. One influence, and only one, can interfere with this normal development of the voice. This is the involuntary and unconscious stiffening of the throat. In the normal practice of singing nothing is involved which could cause the throat to stiffen. True, the first stages of study are usually marked by a slight degree of stiffness, due solely to the lack of practice and experience. This initial stiffness does not tend to become habitual; it disappears before the student becomes aware of it, and leaves no permanent trace on the voice. That is, provided mechanical instruction does not intervene, to introduce the tendency directly to stiffen the throat.