Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1903-11-02
YOU HAVE SIX EARS.
THE ORGANS OF HEARING ARE A
WONDERFUL ser OF MACHINES.

WONDERFUL SET OF MACHINES.
They Include Two Hammers, Two
Anvils, Two SttrrupS, Six Canals
\ Two Snail Shells. Six Drums and
/ Several other Curious Utenails.
wonderful than most people have the
slightest idea of. 1t is marvellous
collection Of instruments for receiving,
magnifying and recording sounds or
vibrations, us the learned term them.
What you do when you speak to u
friend Is to throw the air into vibra-
and the impulses thus caused reach the
trumpet shaped bits of flesh and gristle
you call ears. You Lave Altogether six
ears.
The flaps which are stuck on to each
| side of the head are tile 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 1t en-
tiers the head and ends in q ring. A
| 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 n true drum, for It
means of levers made for that purpose.
| The tightening and slackening are done
quite automatically to suit the various
sounds.
This is how 1t is tightened: In the
middle ear are four tiny bones, the
most peculiar looking bones imagina-
BILE. The biggest is a little odd shaped
bone called the mallet. 1t looks like a
| lilliputian version of Holsters claw.
| Minute muscles are attached to 1t, SO
that 1t may act us lever to increase
or diminish the tension OF the drum
skin. One muscle relaxes the mem
brane, another pulls 1t taut.
4
meet the drum skin of the outer car with
the drum skin of the inner aud 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 namesake, but 1t
is by far the most important Of the
four. BY means OF this alone one can
hear, in fashion. even II all the others
be gone.
A 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 it.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 partA
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
snail's she'll All these make up
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
magnifles 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 eur,
to the membrane covering the entrance
to the labyrinth.
IL you keep your UOutu WlOe 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. II the two
speakers each held an end Of the same
piece OF hard wood against their teeth
even the faintest whisper could be un-
derstood.
You will see from this that what are
commonly called the ears are not es-
senially necessary to herring. 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
vibrnte These vibrations act on the
fibers of the auditory nerve, the tibers
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
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