tion for "ee" it gives a higher tone. Meanwhile, the
pitch of the voice, determined by the vibration of the vocal cords,
may remain the same or vary in any way. The vowel tones differ from
overtones in remaining the same without regard to the pitch of the
fundamental tone that is being sung or spoken, whereas overtones move
up or down along with their fundamental. The vowels, as auditory
sensations, are excellent examples of blends, in that, though
compounds, they usually remain unanalyzed and are taken simply as
units. What has been said of the vowels applies also to the
semi-vowels and continuing consonants, such as l, m, n, r, f, th, s
and sh.

Other consonants are to be classed with the noises. Like a vowel, and
like the timbre of an instrument, a noise is a blend of simple tones;
but the fundamental tone in a noise-blend is not so preponderant as to
give a clear pitch to the total sound, while the other tones present
are often too brief or too unsteady to give a tonal effect.

Comparison of Sight and Hearing

The two senses of sight and hearing have many curious differences, and
one of the most curious appears in mixing different wave-lengths.
Compare the effect of throwing two colored lights together into the
eye with the effect of {232} throwing two notes together into the ear.
Two notes sounded together may give either a harmonious blend or a
discord; now the discord is peculiar to the auditory realm; mixed
colors never clash, though colors seen side by side may do so to a
certain extent. A discord of tones is characterized by imperfect
blending (something unknown in color mixing), and by roughness due to
the presence of "beats" (another thing unknown in the sense of sight).
Beats are caused by the interference between sound waves of slightly
different vibration rate. If you tune two whistles one vibration apart
and sound them together, you get a tone that swells once a second;
tune them ten vibrations apart and you get ten swellings or beats per
second, and the effect is rough and disagreeable.

Aside from discord, a tone blend is really not such a different sort
of thing from a color blend. A chord, in which the component notes
blend while they can still, by attention and training, be "heard out
of the chord", is quite analogous with such color blends as orange,
purple or bluish green. At the same time, there is a curious
difference here. By analogy with color mixing, you would expect two
notes, as C an