The study of the functions of the cranial nerves convinces me that the state of mind which conceives a tone acts upon the organs of speech through the cranial nerves in a way to give vocal expression. In perfect expression the conception and the expression are absolutely synchronous.
RELATION OF PITCH TO RESONANCE.
In the production of a good tone there is an exact relation between pitch and resonance. This relation is provided for in nature and a disobedience to it brings an unpleasant quality into the voice. This is true in both speech and song, for the speaking and singing voices rest upon the same fundamental principles. Speech is one application or use of the voice, song is another. The voice of true speech is as melodic as the voice of song. There are, however, many persons who use their voices better when they sing than when they speak, while others use their voices better in speaking than in singing.
There is a difference between tone and noise. Voice is produced by a succession of vibrating waves of air. In a musical tone the waves are regular in their succession; in noise they are irregular.
Resonance, or echo, is produced by the universal law of reflex action which manifests itself in light, sound, etc. How interesting and delightful is the echo! It makes the mountains, like the morning stars, sing together for joy. Listen to a thunder storm among the mountains. There is a sudden explosion, then a silence, as the vibrating waves of mighty amplitude pass over the valley to wake the voice of the mountain beyond, which, standing like a sentinel on guard, speaks in thunder tones to the next, and that repeats the sublime echo until all the mountains join in the chorus, answering back to the heavens. This law of sympathy, undulating from mountain to mountain, so inspired the Greeks that they said the gods spoke to each other from mountain peak to mountain peak.
Every pitch in the human voice has its corresponding chamber of resonance, formed by the nares, by the trachea, by the pharynx, or by the mouth, and sometimes by more than one of these. The transient resonant chambers are formed by the adjustment of the lips, and by the relation of the tongue to the upper gum, the hard palate, the soft palate, and the pharynx. With the exception of the pharynx, these and the nasal forms constitute the resonant chambers which produce the different elements of speech in our language. The tone, though smooth when it leaves the vocal cords, may be made harsh by the transient resonant chambers. The nares resound different intervals of the scale in different portions of their length, never resounding two intervals in the same portion.
The cultivation of the voice is produced, first, through perfecting the forms of the transient chambers of resonance; second, through establishing perfect freedom and regularity in the action of the vocal cords; third, through developing the rhythmic impulses of the tone. No person ever speaks continuously in a perfect monotone; the pitch is constantly changing with the varying thoughts; as the pitch changes, the resonant chambers change the quality. Nature, unhindered, never reports the same quality on two different degrees of pitch. It is not that the individual, while speaking, intends to change the quality; but nature has so arranged the vocal organs and so determined the laws of acoustics, that unless the voice be interfered with by wrong mental determination, she herself changes the quality as the voice rises or falls.
It is a law of acoustics that a low pitch is resounded in a comparatively large resonant chamber; a high pitch in a comparatively small one. A simple and instructive experiment in illustration of this principle is this: Take a large bottle, strike a C tuning fork, hold it over the empty bottle, and no sound will be heard. The bottle does not respond, because the cavity is too large for the pitch of the fork. If water is poured into the bottle, the air column inside thereby being shortened until the proper sized chamber is formed, by then holding the high-pitched tuning fork over it, the sound of the fork will be resounded by the resonant chamber and the tone will burst forth quite loudly. Use any number of tuning forks, each on a different key, and a resonant chamber can thus be made which will resound each fork.
I once tried an experiment with two tuning forks which were fastened to sounding boxes and which had been tuned to exactly the same pitch. I struck one fork and stopping its vibration, the sound of the other, vibrating responsively, was distinctly heard. The same result was achieved when one of the tuning forks was placed in a remote part of the room. I also placed the fork upon the piano, struck it, and the string of the same pitch, in connection with its overtones, responded. In order that any resonant cavity may resound, the pitch that belongs to that cavity must be struck. Every room in a house, in consequence of its size, its form, and the material of which it is constructed, resounds to a certain pitch. Sometimes in the course of conversation the globe of a chandelier in the room resounds. This is because the pitch which is agreeable to its size, form, and substance is struck.