Page:Popular Science Monthly Volume 13.djvu/60

50 the resounding column of air, from the water to the top of the jar, we find it to be 7½ inches, one-fourth the length of the A-wave. Now, by making a resounder of this size, with an ear-opening in the bottom, we shall have an instrument that will pick out A every time from a sea of sound. This resonator is shown in Fig. 9; and Fig. 10 shows another form of the same instrument. Resonators tuned to the different



notes are made, and by their aid any sound can be analyzed, and each overtone brought out like the throbbing of a single string.

In this way it has been found that the peculiar character, or stamp, of any sound depends on its overtones, and furthermore on exactly what ones, so that by reproducing them any sound can be imitated. Of all sounds those of the human voice are the sweetest. None others are so rich in harmonic overtones, and this brings us to Words.

The vocal mechanism is made in two pieces. One, a wonderful musical instrument with only one vibrator—the vocal chords, Fig. 11—which can tune itself at once to any note. The other, the mouth, as an echo-cave or resonator, no less wonderful in its power of forming itself to resound the harmonics of the vocal tones. This gives the



voice its power of imitating any sound within its reach. We will analyze the voice.

Let the vocal chords sing or vibrate any note, and by merely changing the hollow of the mouth the purely musical sound will turn into what are called the vowel-sounds of speech, the closest position of the mouth making it ee, the deepest oo. Why is this, since the musical note is the same in each? It is because the different positions of the mouth resound to different overtones. While some vowel is sung we