The Human EarDefinition: the organ humans use to detect
sound.http://www.a3bs.com/3d_models.html
The human ear is divided into three sections.
Each part of the ear serves a specific purpose in the task of
detecting and interpreting sound.
The Outer EarPicture a satellite dish that collects radio waves.
The outer ear is similar!The curved formation on the outside ( the
pinna) helps funnel sound down the ear canal to the eardrum.
The Middle EarThe middle ear transfers the energy of a sound
wave by vibrating the three bones found there.
Bones of the Middle EarHammerAnvilStirrupEardrumThese are the
smallest bones in your body!Together, theyre about the size of an
orange seed.
The Stirrup (or stapes)
How Sound Travels in the Middle EarWhen sound waves reach the
middle ear, they cause the eardrum to vibrate.This vibration then
causes the three bones to vibrate.These vibrations are transformed
into longitudinal/pressure waves in the middle ear.
The Inner EarTwo main parts:CochleaAuditory Nerve
The CochleaCoiled like a snail shellContains approximately
300,000 hair cellsIs filled with fluid, through which sound can
travel easily.
Cochlear Hair CellsThese tiny hairs bend because of the
vibrations caused by the sound waves.
Cochlear Hair Cells in Action
The Auditory NerveThe tiny hair cells of the cochlea are set in
motion by vibrationsThe vibrations stimulate tiny nerve cells. The
nerve cells then send signals along the auditory nerve to the
brain.
A sound is not actually heard until the brain receives and
processes these signals.
Put the following steps in order:The stirrup moves back and
forth, creating pressure waves in the cochlea.The bones of the
middle ear (hammer, anvil, & stirrup) vibrate. Hair cells send
an electrical impulse through the auditory nerve. The outer part of
the ear (the pinna) "catches" the sound waves.Sound waves vibrate
the eardrumThe brain receives an electrical impulse and interprets
it as sound. Tiny hair cells in the cochlea move as the waves
pass.The sound waves travel into the ear canal.
