emits a certain lowest possible tone when vibrated. This is called its
_fundamental tone_. The pitch, loudness, and timbre of this tone
depend upon various controlling causes. Usually this fundamental tone
is accompanied by a number of others of higher pitch, blending with it
to form the general tone of that object. These higher tones are called
_harmonics_. The Germans call them _overtones_. They are always of a
frequency which is some multiple of the fundamental frequency. That
is, the rate of vibration of a harmonic is 2, 3, 4, 5, or some other
integral number, times as great as the fundamental itself. A tone
having no harmonics is rare in nature and is not an attractive one.
The tones of the human voice are rich in harmonics.

In any tone having a fundamental and harmonics (multiples), the
wave-train consists of a complex series of condensations and
rarefactions of the air or other transmitting medium. In the case of
mere noises the train of vibrations is irregular and follows no
definite order. This is the difference between vowel sounds and other
musical tones on the one hand and all unmusical sounds (or noises) on
the other.

Human Voice. Human beings communicate with each other in various
ways. The chief method is by speech. Voice is sound vibration produced
by the vocal cords, these being two ligaments in the larynx. The vocal
cords in man are actuated by the air from the lungs. The size and
tension of the vocal cords and the volume and the velocity of the air
from the lungs control the tones of the voice. The more tightly the
vocal cords be drawn, other things being equal, the higher will be the
pitch of the sound; that is, the higher the frequency of vibration
produced by the voice. The pitches of the human voice lie, in general,
between the frequencies of 87 and 768 per second. These are the