The quality and power of resonance is well illustrated by a tuning-fork, which, if set in vibration, can, unaided, scarcely be heard by the person holding it. But if rested on a table, or a plate of glass, or, better still, on the bridge of a violin, its tones may be distinctly heard throughout a large hall.
The vibrating violin string when detached from the body of this instrument, although attuned to pitch, gives absolutely no musical sound; the lips of the player placed on the mouthpiece detached from the tube and bell of the brass instrument produce only a splutter; and a pianoforte without a sounding-board is nil. The air column in the tube of the French horn, and the sounding-board of the pianoforte develop the vibrations caused by the lips and strings into musical tones pleasing to the ear. The tuning-fork alone can scarcely be heard, while the induced vibrations it sets up through properly adjusted resonance may be audible far away.
The vocal cords alone cannot make music any more than can the lips of the cornet player apart from his instrument. The tone produced by the vibrations alone of the two very small vocal bands must, in the nature of things, be very feeble.
Ninety-and-nine persons if asked the question, what produces tone in the human-voice, would reply, "the vibrations of the vocal cords," and stop there, as if that were all; whereas the answer is very incomplete—not even half an answer.
A great deal of the irrational and injurious "teaching" of singing that prevails everywhere, and of the controversy that befogs the subject, is due to the widely prevalent notion that the little vocal cords are the principal cause of tone, whereas they are in themselves insignificant as sound producers.
It is the vibrations of the air in the resonance chambers of the human instrument, together with the induced vibrations of the instrument itself, which give tone its sonority, its reach, its color, and emotional power.
That this is not an empirical statement but a scientific fact, a few simple experiments will demonstrate.
Tone, in the musical sense, is the result of rapid periodic vibration. The pitch of tone depends upon the number of vibrations in a given period; the loudness of tone depends upon the amplitude of the vibrations; the quality of tone depends upon the form of the vibrations; and the form of the vibrations depends upon the resonator.
The fact that pure white light is a compound of all the tints of the rainbow into which it may be resolved by the prism is well known, but the analogous fact that a pure musical tone is a compound of tones of different rates of vibration, tones of different pitch, is not so much a matter of common knowledge, and not so obvious.
Analysis shows that a musical tone consists of a fundamental note and a series of overtones.[5] The ear is quite capable of recognizing many of these overtones and may be trained to do so. The most obvious can be readily separated from a fundamental by a simple experiment.