Download Sensation and Perception - Weebly

The Human Ear
Auditory Sensation and Perception
• How Do We Hear?
• The World of the Deaf
• Artificial Senses - Hearing
PINNA
• Also called the auricle.
The visible part of the
outer ear. It collects
sound and directs it into
the outer ear canal.
EXTERNAL AUDITORY CANAL
•The tube through
which sound
travels to the
eardrum.
EARDRUM
•Also called the
tympanic membrane.
A thin membrane that
vibrates when sound
waves reach it.
MALLEUS/INCUS/STAPES
HAMMER/ANVIL/STIRRUP
•The three bones of the
middle ear that carry
sound vibrations from
the eardrum to the
chochlea.
EUSTACHIAN TUBE
• 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 and allows the bones
of the middle ear to vibrate properly.
When you "pop" your ears as you
change altitude (going up a mountain
or in an airplane), you are equalizing
the air pressure in your middle ear.
SEMICIRCLE 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.
COCHLEA
• A spiral-shaped, fluid-filled
inner ear structure; it is lined
with cilia (tiny hairs) that
move when vibrated and
cause an electrical nerve
impulse to form
(transduction).
VESTIBULAR COCHLEAR NERVE
•Carries electrochemical signals from
the inner ear (the
cochlea) to the brain.
HEARING/AUDITION
• The brain’s ability to receive
sound waves from the outside
world
• Sound waves are the rhythmic
vibrations of air molecules
LOUDNESS
• The intensity/energy of a sound wave, measured
in decibels.
• On a graph, “amplitude” is the height of a sound
wave. The higher the wave, the more force it
will hit the eardrum with, and the resulting sound
is louder. The lower the wave, the less force it
will hit the eardrum with, and the resulting sound
is softer.
• Min = 0 decibels
Max = 120 decibels
PITCH
• Pitch is the property of sound that we
perceive as higher and lower tones.
Changes in pitch are caused by
differences in the frequency at which a
sound wave vibrates.
• On a graph, the more waves per second
results in a higher tone, and the less
waves per second results in a lower tone.
• Pitch is measured in Hertz (Hz) – how
many times a wave repeats per second
• Min = 20
Max = 20,000
TIMBRE
• The distinctive quality of
individual sounds.
• Created by an infinite
combination of high and low
frequencies (pitch), and high
and low amplitudes
(loudness).
Taste
• How Does Taste Work?
• Taste is the sense in humans
and other animals by which five
qualities of a food substance
are distinguished (sweetness,
sourness, saltiness, bitterness,
and umami).
• All food tastes are a result of
their unique combination of
these five basic qualities.
• Bitter taste is perceived by many to
be unpleasant, sharp, or
disagreeable. Common bitter foods
and beverages include coffee,
unsweetened chocolate, bitter melon,
beer, olives, and citrus peel.
• Saltiness is a taste produced primarily
by the presence of sodium ions.
• Sourness is the taste that detects
acidity.
• Sweetness is produced by the
presence of sugars, some proteins and
a few other substances.
• Umami is the name for the taste
sensation produced by compounds
such as glutamate, found in beef, lamb,
parmesan and cheese, as well as soy
sauce.
• The mucous membrane lining of the
tongue is covered with tiny projections
of papillae, each of which houses 200
to 300 taste buds. In humans, the
papillae are located on the surface and
sides of the tongue, the roof of the
mouth, and the entrance to the
pharynx.
• Foods are broken down by saliva.
Food molecules are absorbed by the
papillae and then into the taste buds.
• The unique properties of the food
molecules will stimulate the
thresholds for their respective taste
sensors. Depending on which
combination of sensors are activated,
a different message will be sent to the
brain to be processed.
• The somatosensory cortex will
decode the information received (this
food is a combination of sweet and
sour).
• The hippocampus will label the food
based on our previous experiences
with that combination (that specific
combination of sweet and sour is
called barbecue) .
• The amygdala will add an emotional
experience to the food (do I like that
barbecue or not?).
• Very slight regional differences in
sensitivity to compounds exist on
the tongue, though these regional
differences are subtle and do not
conform exactly to the traditional
tongue map. Individual taste
buds, in fact, typically respond to
compounds evoking each of the
five basic tastes.
• Supertasters are those individuals
who have approx. 25% more
taste buds than the average
person. About 25% of the
population fit into this category.
• Non-tasters are those individuals
who have approx. 25% less taste
buds than the average person.
About 25% of the population fit
into this category.
Think About It
• What influences your food
preferences? When you go to
the store to purchase food, why
do you choose one specific
brand over another? Do you
find that you always choose
Cap’n Crunch over the
generic store brand? Why or
why not?
Is it true?
• Do name brand foods really taste
better than their store brand
competitors?
• If current research is correct, many
people base their food purchases on
the perception of better taste rather
than actual taste. Due to advertising
exposure, product placement, higher
pricing, catchy slogans, etc., many
people believe that name brands taste
better. But do they?
Let’s Test It !!
• In a blind taste-test, if this
research is correct, we
should be able to determine
which is the name brand
and which is the store brand
product on taste alone as
well. Can we?
Smell
• Olfactory receptors/cells in
the upper nasal passages
detect odor molecules in the
air.
• The unique chemical
properties of each odor
molecule create the
perceptions of smell.
• Humans can perceive
approximately 10,000
different scents.
• Odor molecules dissolve in the
mucus membrane of the upper nasal
passage, and their unique chemical
properties are absorbed by cilia.
• The cilia are responsible for
transducing the message and
sending it to the olfactory bulb in the
frontal lobe for identification.
• The hippocampus and the amygdala
add context and emotional
responses to the perception.
Smell
Smell
Smell
Touch
Touch
• Touch receptors are on the skin
• Four basic skin senses are
– Pain
– warmth
– cold
– pressure
• All skin sensations are a combination
of these four basic senses
Sensitive Parts of the Body
Most Sensitive
• Back of knees
• Neck region
• Bend of elbow
Least Sensitive
• Tip of the Nose
• Sole of foot
• Ball of thumb
Gate-Control Theory of Pain
• Experience of
pain depends (in
part) on whether
the pain impulse
gets past
neurological
“gate” in the
spinal cord and
thus reaches the
brain.