Download Document

The Ear, Sound, Hearing, and the
answer to everything?
Essential Question
• How do we hear?
• What does the auditory system (ear + brain)
look like and how does it work?
Objectives
• Name the parts of the ear?
• Describe how sound is heard?
• Explain how energy, sound waves, and hearing
are related.
How is energy, sound waves, and hearing related.
• A mechanical wave is a repeating disturbance or
vibration that transfers or moves energy from place
to place.
• Waves are created when a source of energy (force)
causes a vibration.
• A vibration is a repeated back-and-forth or up-anddown motion.
• Waves carry energy through a medium without
transporting matter.
• A medium is a material through which waves can
travel. It can be a solid, liquid, or gas.
• When waves travel through a medium, the particles
of the medium are not carried along with the wave.
How is energy, sound waves, and hearing related.
• The disturbances (a Mechanical energy source)
that travel as sound are called vibrations.
• Remember, sound waves require a medium to
travel and are LONGITUDINAL (compression)
WAVES
• A medium is a gas, liquid, or solid and energy
goes through the medium without carrying the
medium
• Think slinky
How is energy, sound waves, and hearing related.
Sound is collected by the visible part of the ear and
directed through the outer ear canal. Mechanical
Energy
The sound makes the eardrum vibrate, which in turn causes
a series of three tiny bones (the hammer, the anvil, and the
stirrup) in the middle ear to vibrate. Mechanical Energy
The vibration is transferred to the snail-shaped cochlea in
the inner ear. Hydraulic Energy
The cochlea is lined with sensitive hairs which trigger the
generation of nerve signals that are sent to the brain.
Electrical and Chemical energy
The perception of sound is found in this area
The Ear
Activity Draw and label, do not copy and paste.
Anvil
Hammer
Stirrup
Estuation tube
• Hearing…
– The hearing system is based solely on physical
movement.
– Sound occurs when it vibrates in matter. (Solid,
Liquid, Gas).
Copyright © 2010 Ryan P. Murphy
• To hear, you must…
– Direct the sound waves into the Ear Canal using
the Pinna aka the Outer ear:
Pinna
Copyright © 2010 Ryan P. Murphy
Function of Outer Ear
•
•
•
•
Collect sound
Focuses sound
Reverberator
Protection
Pinna
• The visible portion that is
commonly referred to as
"the ear"
• Helps localize sound sources
• Directs sound into the ear
• Each individual's pinna
changes the acoustic wave
traveling into the auditory
canal and everyone hears
differently
Middle Ear
 1999, Electronic Deaf Education Network
Function of Middle Ear
• Conduction
– Conducts sound from the outer ear to the inner ear
• Protection
– Creates a barrier that protects the middle and inner areas from
foreign objects
• Transducer (A transducer is a device that converts a signal in one
form of energy to another form of energy.)
– Converts acoustic energy to mechanical energy
– Converts mechanical energy to hydraulic energy
• Amplifier
– only about 1/1000 of the acoustic energy in air would be
transmitted to the inner-ear fluids (about 30 dB hearing loss) if
the middle ear does not work correctly
• To hear, you must…
– Direct the sound waves into the hearing part of
the ear to the ear drum.
– The eardrum vibrates from the compression and
rarefaction of the air.
Pinna
The Eardrum
• The eardrum separates the outer
ear from the middle ear
• Creates a barrier that protects
the middle and inner areas from
foreign objects
• Cone-shaped in appearance
– about 17.5 mm in diameter
• The eardrum vibrates in
response to sound pressure
waves.
• The membrane movement is
incredibly small
– as little as one-billionth of a
centimeter
Eustachian Tube provides a way
to equalize the pressure between
in middle ear and outer ear
From www.unc.edu/courses/psyc21/3-26-99/sld010.htm
Ossicles: Bones of the middle ear
M. Malleus
(hammer)
I. Incus (anvil)
S. Stapes
(stirrup)
smallest
bone of the
body
• To hear, you must…
– Direct the sound waves into the hearing part of the ear.
– Mover with the air pressure vibrations in the ear drum and
ossicle bones.
– Change these vibrations into an electrical signal in the
Cochlear organ and out through the auditory nerve that
your brain can understand.
Pinna
The inner ear also houses our organs of balance
• Organs of balance are part of the inner ear
• They include
– Semicircular canals
• These organs sense body position and movement
Copyright © 2009 Pearson Education, Inc.
Answer in your ISN: the next slide shows the answers.
Word Bank: Ear Drum, Eustachian Canal, Anvil, Cochlea, Hammer
• A tiny bone that passes vibrations from the hammer to the stirrup.
• A spiral-shaped, fluid-filled inner ear structure; it is lined with cilia
(tiny hairs) that move when vibrated and cause a nerve impulse to
form.
• (Also called the tympanic membrane) a thin membrane that
vibrates when sound waves reach it.
• A tube that connects the middle ear to the back of the nose; it
equalizes the pressure between the middle ear and the air
outside.
• A tiny bone that passes vibrations from the eardrum to the anvil.
Copyright © 2010 Ryan P. Murphy
• Use Deductive Reasoning. (Frontal Cortex)
• Use your deductive reasoning skills: Word Bank:
• Ear Drum, Eustachian Canal, Anvil, Cochlea, Hammer
• Anvil
- A tiny bone that passes vibrations from the hammer
to the stirrup.
Cochlea
- A spiral-shaped, fluid-filled inner ear structure; it
is lined with cilia (tiny hairs) that move when vibrated and cause a
nerve impulse to form.
Eardrum
-(Also called the tympanic membrane) a thin
membrane that vibrates when sound waves reach it.
Eustachian Canal - A tube that connects the middle ear to the
back of the nose; it equalizes the pressure between the middle ear
and the air outside.
– When your ears pop as you change altitude (going up a mountain or in an airplane),
you are equalizing the air pressure in your middle ear.
• Hammer
- A tiny bone that passes vibrations from the
eardrum to the anvil.
Copyright © 2010 Ryan P. Murphy
• Answer in you ISN: The next slide has the answers
Word Bank: Pinna, Nerves, Stirrup, Ear Canal, Semicircular
Canals.
• These carry electro-chemical signals from the inner ear
(the cochlea) to the brain.
• The tube through which sound travels to the eardrum.
• The visible part of the outer ear. It collects sound and
directs it into the outer ear canal
• Three loops of fluid-filled tubes that are attached to the
cochlea in the inner ear. They help us maintain our sense
of balance.
• A tiny, U-shaped bone that passes vibrations from the
stirrup to the cochlea. This is the smallest bone in the
human body (it is 0.25 to 0.33 cm long).
Copyright © 2010 Ryan P. Murphy
• Use Deductive Reasoning. (Frontal Cortex)
• Word Bank: Pinna, Nerves, Stirrup, Ear Canal,
Semicircular Canals.
• Nerves - These carry electro-chemical signals from the
inner ear (the cochlea) to the brain.
Ear canal - The tube through which sound travels to the
eardrum.
Pinna - The visible part of the outer ear. It collects sound
and directs it into the outer ear canal
Semicircular Canals - Three loops of fluid-filled tubes
that are attached to the cochlea in the inner ear. They
help us maintain our sense of balance.
Stirrup - A tiny, U-shaped bone that passes vibrations
from the stirrup to the cochlea. This is the smallest bone
in the human body (it is 0.25 to 0.33 cm long).
Copyright © 2010 Ryan P. Murphy
• Loudness is measured in decibels (dB) –
– This is the force of sound waves against the ear. The
louder the sound, the more decibels.
–
–
–
–
–
–
–
–
–
Ticking Watch 20
Whisper 30
Normal Speech 50
Car 60
Alarm Clock 80
Lawn Mower 95
Chain Saw 110
Jackhammer 120
Jet Engine 130
Copyright © 2010 Ryan P. Murphy
• Sounds that are too loud or that last a long time
can cause Noise-induced hearing loss (NIHL). Our
sensitive hair cells convert sound energy into
electrical signals that travel to the brain and can
become damaged. Once damaged, our hair cells
cannot grow back.
Copyright © 2010 Ryan P. Murphy