Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1903-08-29
YOU HAVE SIX EARS.
THE ORGANS OF HEARING ARE A
WONDERFUL SET OF MACHINES.

Ehey Include Two Hammers, Two
AnviIs, Two StirruDs, Six Canals,
Two Snail Shells, Six Drums and
Several Other Curious Utensils.
The hearing apparatus is far more
wonderful than most people have the
slightest idea of. 1t is a marvellous
collection of instruments for receiving,
magnifying and recording sounds or
vibrations, as the learned term them.
What you do when you speak to
friend is to throw the air into vibra-
ton. Your vocal organs strike the air,
and the impulses thus caused reach the
trumpet shaped bits of flesh and gristle
you call ears. You have altogether six
ears.
The flaps which are stuck on to each
side of the head are the outer ears. Be
sides these there are the middle ears
and the inner ears, all of which lie in
cavities in the bones of the head. All
that the flaps do is to collect and con-
centrate the vibrating currents of air,
so that they may strike the ear drums.
These latter are really the middle
ears. The outer ear narrows as it en-
tiers the head and ends in ring. y
membrane is stretched over this ring
much in the same way as piece of
parchment is stretched over the head
of drum.
The ear drum is true drum, for 1T
can be frightened and slackened by
means of levers made for that purpose
The tightening and slackening are done
iaaI TO fl,
sounds.
This is how it is frightened: In the
middle ear are four tiny bones, the
most peculiar looking bones magma
BILE. The biggest Is n little odd shaped
bone called the mallet. 1t looks like
lilliputian version of a Holsters claw.
Minute muscles are attached to it, so
that it may act as a lever to increase
or diminish the tension of the drum
skin. One muscle reiaXes the mem
brane, another pulls ii taut.
The four bones form Il chain to con
meet the drum skin Of the outer ear with
the drum skin of the inner and so to
conduct the sound. The next bone to
the mallet is the anvil, then come the
spherical bone and the stirrup, which
looks exactly like its namcsake, but II
is by far the most important Of the
four. By means of this alone one can
hear, in fashion, even if all the others
be gone.
\ bony, gristly tube Joins the ear
drum with the back of the mouth at
the side of the soft palate. Hence the
four bones are always in bath OF air,
quite naked, as il were. 1t is owing to
this that people who are somewhat
deaf are able TO hear better when they
listen with their mouths open.
Now we come to the inmost ear,
which is made up of three parts. The
first one is called the vestibule, or hall,
and it has drumhead to which the
chain of little bones is attached.
The hall leads to the other parts,
both of which consist of tortuOus tubes
along which the sound passes. one
part is made of three semicircular
canals. The other is shaped exactly as
n snaiTs shell. All these make up n
peculiar labyrinth, and all are COM
pletely filed with curious fluid. Their
walls are lined with the soft, pulpy
nerves of hearing which communicate
with the brain. Owing TO these COM
pick and winding cavities, great eX-
tent of nerves is exposed for the recep-
ton of sound
Now let us see what happens when
somebody says Heart to you.
The air is thrown into vibrations,
which spread out and out until they
touch the side of your head. There
the fleshy flap on one side collects and
magni1ies the vibrations.
Down the ear funnel they pass until
they reach the membrane of the drum
of the ear. They strike on the mem
brane, which adaptS itself to them.
Then the vibrations are communicated,
through the bones in the middle ear,
to the membrane covering the entrance
to the labyrinth.
If you keep your mouth wide open
the air vibrations pass direct to the
little bones. The impulses of the air
are not interrupted by first having to
strike the membrane of the drum; that
is all the difference.
People could easily converse with
their ears sealed up. If the two
speakers each held an end of the same
piece of hard wood against their teeth
even the faintest whisper could be I'M
derstood.
You will see from this that what are
commonly called the ears are not es-
sentially necessary to hearing, after
all.
Well, however the vibrations are re-
ceived, they finally strike against the
membrane covering the entrance to the
hall of the labyrinth. Thence they
make the fluid which fills the labyrinth
vibrate. These vibrations act on the
fibers of the auditory nerve, the fibers
which coat the inner ear. Along this
nerve the impressions are communicate
ed to the brain. In this manner the
sensation of sound is produced, and