The
ear is a very sophisticated receiver and transmitter of sound from the
outside world to the brain. To achieve the hearing process, the ear
gathers physical vibrations and turns them into electrical signals in a
very unique and complex operation. The ear is divided into three parts;
the outer, middle and inner ear. Each part plays a very specific role
in the hearing process.
The
outer ear acts as a collector for sound vibrations. These vibrations
are funneled into the ear canal and down toward the eardrum. The
collected sound waves cause the eardrum to vibrate, which in turn
transmits the vibration to the middle ear.
The middle ear is an air-filled cavity between the eardrum and the
inner ear. The three bones of the middle ear (malleus, incus, and
stapes) mechanically transfer sound vibrations to the inner ear. The
malleus, (commonly called hammer) is connected to the eardrum.
Vibration of the eardrum causes the malleus to transfer these
vibrations to the incus (anvil). The incus in turn is connected to the
stapes (stirrup). The stapes completes the transfer of the airborne
vibrations through mechanical means to the inner ear.
The inner ear consists of the cochlear (hearing) and vestibular
(balance) organs. The cochlea is a fluid-filled, snail shaped organ
that completes the transformation of airborne vibrations (sound) into
electrical signals. The stapes is connected to the cochlea at the oval
window, a membrane at the entrance to the inner ear. When this membrane
vibrates, wavelike motions of the fluid in the cochlea stimulate hair
cells that line the cochlea. These hair cells trigger an electrical
impulse that travels directly to the brain via the auditory nerve.
