Human Ear. The human ear, the organ of hearing in man, is a complex
mechanism of three general parts, relative to sound waves: a
wave-collecting part; a wave-observing part, and a wave-interpreting
part.

The outer ear collects and reflects the waves inwardly to beat upon
the tympanum, or ear drum, a membrane diaphragm. The uses of the rolls
or convolutions of the outer ear are not conclusively known, but it is
observed that when they are filled up evenly with a wax or its
equivalent, the sense of direction of sound is impaired, and usually
of loudness also.

The diaphragm of the ear vibrates when struck by sound waves, as does
any other diaphragm. By means of bone and nerve mechanism, the
vibration of the diaphragm finally is made known to the brain and is
interpretable therein.

The human ear can appreciate and interpret sound waves at frequencies
from 32 to about 32,000 vibrations per second. Below the
lesser-number, the tendency is to appreciate the separate vibrations
as separate sounds. Above the higher number, the vibrations are
inaudible to the human ear. The most acute perception of sound
differences lies at about 3,000 vibrations per second. It may be that
the range of hearing of organisms other than man lies far above the
range with which human beings are familiar. Some trained musicians are
able to discriminate between two sounds as differing one from the
other when the difference in frequency is less than one-thousandth of
either number. Other ears are unable to detect a difference in two
sounds when they differ by as much as one full step of the chromatic
scale. Whatever faculty an individual may possess as to tone