is due to harmonics or overtones. Could we but see
the sonorous waves in the air during the transmission of the sound of a
voice, we should see stamped on it the conditions of motion upon which its
characteristic qualities depended; which is due to the fact that every
vocal sound whose vibrations have a complex form can be decomposed into a
series of simple notes all belonging to the harmonic series. These
harmonics or overtones will be considered later when dealing with the
timbre or quality of the human voice.

The vocal instrument is unlike any other musical instrument; it most nearly
approaches a reed instrument. The clarionet and the oboe are examples of
reed instruments, in which the reed does not alter but by means of stops
the length of the column of air in the resonating pipe varies and
determines the pitch of the fundamental note. The organ-pipe with the
vibrating tongue of metal serving as the reed is perhaps the nearest
approach to the vocal organ; but here again it is the length of the pipe
which determines the pitch of the note.

The vocal instrument may be said to consist of three parts: (1) the
bellows; (2) the membranous reed contained in the larynx, which by the
actions of groups of muscles can be altered in tension and thus variation
in pitch determined; (3) the resonator, which consists of the mouth, the
throat, the larynx, the nose, and air sinuses contained in the bones of the
skull, also the windpipe, the bronchial tubes, and the lungs. The main and
important part of the resonator, however, is situated above the glottis
(the opening between the vocal cords, _vide_ fig. 6), and it is capable of
only slight variations in length and of many and important variations in
form. In the production of musical sounds its chief influence is upon the
quality of the overtones and therefore upon the timbre of the voice;
moreover, the movable structures of the resonator, the lower jaw, the lips,
the tongue, the soft palate, can, by changing the form of the resonator,
not only impress upon the sound waves particular overtones as they issue
from the mouth, but simultaneously can effect the combination of vowels and
consonants with the formation of syllables, the combination of syllables
with the formation of words, and the combination of words with the
formation of articulate language. The reed portion of the instrument acting
alone can only express emotional feeling; the resonator, the effector of
articulate spee