YEAR 9 SCIENCE
LIGHT & SOUND EXTENDED RESPONSE TASK
(E.R.T.)
- RESEARCH HELP: Sound energy & the ear -
STUDENT NAME:
CLASS TEACHER:
SCIENCE CLASS:
Shannon Baker
Mrs Dover
9.3
Sound energy and the ear.
CHOSEN TOPIC:
Vertigo
CHOSEN CONDITION
Anatomy of the human ear
http://www.wisc-online.com/Objects/ViewObject.aspx?ID=ap1502
The middle ear, separated from the external ear by the eardrum, is an
air-filled cavity (tympanic cavity) carved out of the temporal bone. It
connects to the throat/nasopharynx via the Eustachian tube. This earthroat connection makes the ear susceptible to infection (otitis media).
The eustachian tube functions to equalize air pressure on both sides of
the eardrum. Normally the walls of the tube are collapsed. Swallowing
and chewing actions open the tube to allow air in or out, as needed for
equalization. Equalizing air pressure ensures that the eardrum vibrates
maximally when struck by sound waves.A djoining the eardrum are
three linked, movable bones called "ossicles," which convert the sound
waves striking the eardrum into mechanical vibrations. The smallest
bones in the human body, the ossicles are named for their shape. The
hammer (malleus) joins the inside of the eardrum. The anvil (incus),
the middle bone, connects to the hammer and to the stirrup (stapes).
The base of the stirrup, the footplate, fills the oval window which leads
to the inner ear. The inner ear consists of a maze of fluid-filled tubes,
running through the temporal bone of the skull. The bony tubes, the
bony labyrinth, are filled with a fluid called perilymph. Within this bony
labyrinth is a second series of delicate cellular tubes, called the
membranous labyrinth, filled with the fluid called endolymph. This
membranous labyrinth contains the actual hearing cells, the hair cells of
the organ of Corti. There are three major sections of the bony labyrinth:
The front portion is the snail-shaped cochlea, which functions in
hearing. The rear part, the semicircular canals, helps maintain balance.
Interconnecting the cochlea and the semicircular canals is the vestibule,
containing the sense organs responsible for balance, the utricle and
saccule. The inner ear has two membrane-covered outlets into the airfilled middle ear - the oval window and the round window. The oval
window sits immediately behind the stapes, the third middle ear bone,
and begins vibrating when "struck" by the stapes. This sets the fluid of
the inner ear sloshing back and forth. The round window serves as a
pressure valve, bulging outward as fluid pressure rises in the inner ear.
Nerve impulses generated in the inner ear travel along the
vestibulocochlear nerve (cranial nerve VIII), which leads to the brain.
This is actually two nerves, somewhat joined together, the cochlear
nerve for hearing and the vestibular nerve for equilibrium.
http://webschoolsolutions.com/patts/systems/ear.htm
http://en.wikipedia.org/wiki/File:Anatomy_of_the_Human_Ear.svg
The ear is the organ of hearing. The parts of the ear include:external or
outer ear, consisting of:pinna or auricle - the outside part of the
ear.external auditory canal or tube - the tube that connects the outer
ear to the inside or middle ear.tympanic membrane - also called the
eardrum. The tympanic membrane divides the external ear from the
middle ear.middle ear (tympanic cavity), consisting of:ossicles - three
small bones that are connected and transmit the sound waves to the
inner ear. The bones are called: malleus incus stapes
Eustachian tube - a canal that links the middle ear with the throat area.
The Eustachian tube helps to equalize the pressure between the outer
ear and the middle ear. Having the same pressure allows for the proper
transfer of sound waves. The eustachian tube is lined with mucous, just
like the inside of the nose and throat.inner ear, consisting of:cochlea
(contains the nerves for hearing)vestibule (contains receptors for
balance)semicircular canals (contain receptors for balance)
http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/ent/anatomy.html
The physiology of the human ear
Hearing starts with the outer ear. When a sound is made outside the
outer ear, the sound waves, or vibrations, travel down the external
auditory canal and strike the eardrum (tympanic membrane). The
eardrum vibrates. The vibrations are then passed to three tiny bones in
the middle ear called the ossicles. The ossicles amplify the sound and
send the sound waves to the inner ear and into the fluid-filled hearing
organ (cochlea).Once the sound waves reach the inner ear, they are
converted into electrical impulses which the auditory nerve sends to the
brain. The brain then translates these electrical impulses as sound.
http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/ent/anatomy.html
http://www.wisc-online.com/Objects/ViewObject.aspx?ID=ap1502
The different structures of the human ear and the
function each structure plays in hearing
Functions of the Ear
We have understood the different parts of a human ear and got an overview of their
functions. Now, let us have a look at the functions of the ear, in a little detail.
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The pinna and the ear canal deliver the sound waves to the middle ear.
Foreign bodies like insects, dust, etc. are prevented from gaining entry into the
ear due to the presence of wax and hair in this region. This helps in preventing
many ear infections.
The ear drum vibrates according to the frequency and the amplitude of sounds
that strike it.
The middle ear function of human ear is to transmit and amplify the sounds
vibrated from the eardrum towards the oval window. It also acts as a
dampener to loud sounds that may damage the cochlea.
The round window is a flexible membrane present at the opposite end of the
fluid filled channels from the oval window. The round window function of human
ear is to keep the cochlear fluids contained within the scala vestibuli and scala
tympani. It also functions as a multiplier of the sound waves generated from
the oval window membrane.
The malleus transmits sound vibrations from the eardrums to the incus.
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The incus transmits the sound vibrations to the stapes.
The stapes transmit the vibrations to the membrane of the inner ear present
inside the fenestra ovalis.
The semicircular canals function is to maintain the balance by responding to
gravity and the acceleration changes of the head.
The mastoid bone acts as a amplifier of certain sounds that are in the low
frequency range.
The cochlea, the actual organ that helps in hearing functions as a sound wave
interpreter and converter.
http://www.buzzle.com/articles/diagram-of-the-ear-and-its-function.html
Parts and Functions of the ear
The human ear is divided into five parts. These five parts of human ear, have specific functions
that help in the process of hearing.
Parts of Human Ear
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Outer Ear
Middle Ear
Inner Ear
Acoustic Nerve
Central Auditory Processing Centers
Outer ear is divided into the pinna and the external auditory meatus. The pinna, also known as
the auricle is the external ear part that is located and seen on each side of our head. It is made
up of cartilage and soft tissue. This helps in maintaining a particular ear shape and also remains
pliable. The pinna is like a funnel that collects the sound vibrations from around us and funnels
them towards the external auditory meatus.
The external auditory meatus is also called as the ear canal. The ear canal helps understand and
determine the source and direction of the sound. It is only ¼ inch in diameter and extends from
the pinna to the tympanic membrane. The tympanic membrane is commonly called as the
eardrum. The skin and hairs cover the outer ear canal foundation and thecerumen gland or the
wax gland is present in this area. The ear canal develops into a bony structure tightly covered
by skin, near the eardrum.
The middle ear is the structure that begins at the end of the tympanic membrane. There are
three tiny bones known as the ossicles that make up the middle ear. These bones connect the
eardrum to the inner ear. Sound waves funneled in through the pinna, hit the eardrum. This
causes the eardrum to move back and forth, in other words, vibrate, causing the ossicles to
move. This causes the sound waves to convert into mechanical vibration.
The three tiny bones forming the ossicles are malleus, incus and stapes. The malleus also
known as the hammer is connected to the eardrum on one side and the incus, known as the
anvil on the other side. The anvil is connected to the third bone stapes, also called the stirrup.
The sound waves converted into mechanical energy are transferred through this ossicular chain.
There is an in and out movement at the stirrup base known as the stapes footplate, that
matches the incoming sound waves. The beginning of the inner ear is marked by the oval
window that fits in the stapes footplate.
The inner ear houses the sensory organs that help in hearing and maintaining balance. The
part of human ear involved in the function of hearing is the cochlea. Another major function of
the human ear is to maintain balance of the body. The different parts of the human ear that
help in balancing are the semicircular canals consisting of the utricle and thesaccule present in
the inner ear.
The bony structure that is shaped like a snail and filled with endolumph and perilymph fluid is
called the cochlea. The sensory receptor called the Organ of Corti is present inside the cochlea.
It has hair cells and nerve receptors, required for hearing.
The middle ear movement pushes the mechanical energy in the oval window inside the cochlea.
The tiny hair cells are stimulated due to the force that moves the fluids inside the
cochlea. Pitches or the specific sound frequencies stimulate specific individual hair cells in the
inner ear. Thus, certain frequencies are responded by certain hair cells. The hair cells translate
signals into nerve impulses. The cochlear portion of the VIII cranial nerve, the acoustic nerve,
transmit the nerve impulses to the brain.
The acoustic nerve is the part of human ear that transmits impulses from the cochlea to the
mid brain region, the cochlear nucleus, and further on to other pathways in the brain, that end
in the auditory cortex of the brain. The nerve fibers of each ear are divided into two pathways
from the cochlear nucleus. Of these two pathways, one ascends towards the auditory cortex in
one hemisphere of the brain and the other crosses over and ascends to the other hemisphere of
the brain. Thus, the function of the human ear nerve fibers pathway is to transmit data or
information received from both ears to both the hemispheres of the brain.
The central auditory system function of human ear is to process auditory information carried
to the brain. The central auditory system plays role in the following functions of human ear:
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The localization and lateralization of the sound
Differentiating between the different sounds
Temporal resolution, masking, integration and ordering
Reducing the auditory performance when there are competing acoustic signals
Reducing the auditory performance when there is a presence of degraded acoustic signal
http://www.buzzle.com/articles/diagram-of-the-ear-and-its-function.html
How does sound pass through the ear and to the brain?
When an object makes a noise, it sends vibrations (better known as sound waves)
speeding through the air. These vibrations are then funnelled into your ear canal by
your outer ear. As the vibrations move into your middle ear, they hit your eardrum
and cause it to vibrate as well. This sets off a chain reaction of vibrations. Your
eardrum, which is smaller and thinner than the nail on your pinkie finger, vibrates
the three smallest bones in your body: first, the hammer, then the anvil, and
finally, the stirrup. The stirrup passes the vibrations into a coiled tube in the inner
ear called the cochlea. The fluid-filled cochlea contains thousands of hair-like nerve
endings called cilia. When the stirrup causes the fluid in the cochlea to vibrate, the
cilia move. The cilia change the vibrations into messages that are sent to the brain
via the auditory nerve. The auditory nerve carries messages from 25,000 receptors
in your ear to your brain. Your brain then makes sense of the messages and tells
you what sounds you are hearing.
http://library.thinkquest.org/3750/hear/hear.html
How do we hear?Hearing starts with the outer ear. When a sound is made outside
the outer ear, the sound waves, or vibrations, travel down the external auditory
canal and strike the eardrum (tympanic membrane). The eardrum vibrates. The
vibrations are then passed to three tiny bones in the middle ear called the ossicles.
The ossicles amplify the sound and send the sound waves to the inner ear and into
the fluid-filled hearing organ (cochlea).Once the sound waves reach the inner ear,
they are converted into electrical impulses which the auditory nerve sends to the
brain. The brain then translates these electrical impulses as sound.
http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/ent/anatomy.html
http://www.learningthroughlistening.org/SiteData/images/How%20the%20Ear%20Hears/4e832295f99dacb904efcfabe43d0878
/How%20the%20Ear%20Hears.jpg
Where may problems occur in human hearing, resulting in
reduction or alteration of normal hearing?
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