I use the scale of E as a means of revealing to the ear points wherein the voice shows signs of failure. I use this scale because within it lie all the principal resonances involved in voice-production. By this I mean that somewhere between the interval G# to C# an oral resonance is developed in the majority of voices. This seems to be coincident with the action of the lips, the tongue and the soft palate, and the other muscles that go to increase or to decrease the size of the oral cavity. From C# to E above middle C the principal changes occur which contribute to the development of the nasal resonance. Some rare voices, however, continue their oral resonance as high as F# before changing. It has occurred to me so often in the course of my practice that a peculiarly apt reason exists for making E the foundation-note of the test-scale employed in the operating room, that I lay particular stress upon it. It has seemed the most easeful note for the patient to sound, whatever his vocal condition, and I have been tempted to call it the "nature tone," because it may be said to sing itself. At least, it can be sounded with naturally open throat and without calling into perceptible use the multiplied enginery of muscular forces which are required for the formation of the higher tones of the scale. Consider for a moment this enginery of muscular forces at the command of the singer, and which his intelligent and ripe knowledge must guide. The muscles used in voice-production may be divided as to action and location into ten groups. In these ten groups there are one hundred and seventeen individual muscles. Three of these act alone. One hundred and fourteen act in pairs, making fifty-seven pairs. Again, these muscles are controlled by nerves, some of which act alone and others in combination. In one instance, a single nerve presides over two large groups of muscles. Then, in still another instance, two separate nerves are required to control the action of one small group--the palate group. The distribution is as follows: Single muscles, 3; muscles in pairs, 114; groups of muscles, 10; nerves acting alone, 17; nerves acting with others (eight groups), 88. By taking these figures and increasing them in arithmetical progression, it is possible to calculate what a multiplicity of nerve and muscle effort is involved in a sneeze. Everything that appertains to the vocal mechanism is spasmodically involved at once, and the enormous sum total of muscle and nerve movement, individualized, is 465,120. This shows how absurd is the theory of conscious control of the machinery of voice-production. As I have frequently pointed out, the adjustments of the vocal tract to the tone to be produced are responses to the will, physical reflexes of the tones which the singer hears mentally; so that voice is mental audition converted by responsive physical adjustment into audible tone.