Hearing, Touch, Taste and
Smell
Hearing
Audition – the sense of
hearing
Frequency of Sound Waves
• frequency - the number of the waves gives us
the pitch if the sound.
Amplitude of Sound Waves
• amplitude - the height of the wave of the
sound.
Absolute Threshold
• Absolute Threshold =
zero decibels
• 10 decibels = 10X
increase in sound
intensity
• Example:
– A 30 decibel sound is
_____ times louder than a
10 decibel sound
– A 40 decibel sound is
_____ times louder than a
10 decibel sound
Parts of the Ear
Transduction
• Overview – Eardrum, Hammer, Anvil, Stirrup, Oval
Window, Cochlea, Auditory Nerve, Temporal Lobe,
Auditory Cortex
1.
Outer Ear
Ear Drum – tight membrane that vibrates with sound
waves. Transmits sound to the bones of the middle
ear.
2.
Middle Ear
hammer, anvil, stirrup to cochlea’s oval window
3.
Inner Ear
Cochlea – coiled fluid filled tube where transduction
occurs
–
Oval window’s vibrations cause basilar membrane’s
hair cells to turn vibrations into neural impulses
It is all
4.
Auditory Nerve – send neural messages via the
about the
thalamus to the auditory cortex in the brain.
vibrations!!!
5.
Thalamus to Temporal lobes Auditory cortex
The structure of the ear
Bones of the middle ear = the hammer, anvil, stirrup which vibrate with
the eardrum.
The structure of the ear
Mechanical vibrations triggered by sound waves are
transduced into neural impulses by _____________?
_____________ do the same job for vision as __________
do for audition
Neural impulse to the brain
Perceiving Loudness
• Damage to Basilar membrane’s hair cells
= hearing loss (lose sensation of soft
sounds)
– # of activated hair cells allows us to
perceive loudness
– Compression – harder to hear sounds are more
amplified than loud sound
Pitch Theories
Place Theory and Frequency Theory
Place Theory or Herman von
Helmholtz Theory
• Brain determines
pitch by recognizing
the place on the
membrane that is
generating the
neural impulse
• Best explains how we
sense high pitches
Frequency Theory
• Brain knows pitch by the
frequency of the neural
impulse
– Frequency (speed) of sound wave
matches the speed of the neural
impulse.
• Theory limitations: Can’t
explain high pitch sounds
(neural impulses can only travel
at 1000 impulses per sec.)
• Best explains how we hear low
pitches
• Example:
Volley Principle
• Neural cells
alternate firing in
rapid succession
• Can achieve a
combined frequency
of above 1000
waves/sec
Locating Sound
• Sound waves strike
one ear sooner and
more intensely in the
direction of the
sound
Deafness
Conduction Deafness
• Damage to the
mechanical system that
conducts vibrations in
the middle ear (hammer,
anvil, stirrup).
• You can replace the
bones or get a hearing
aid to help.
• Example:
•
•
•
•
•
Nerve (sensorineural)
Deafness
The hair cells on the basilar
membrain in the cochlea get
damaged.
Loud noises can cause this
type of deafness.
NO WAY to replace the hairs.
Cochlea implant - converts
sound waves to into electrical
signals.
Example:
Touch
• Receptors located in our skin.
• Types of touch
–Pressure*
–Warmth
–Cold
–Pain
• Sensation of hot
Kinesthetic Sense
• Tells us where our
individual body parts
are.
• Receptors located in
our joints, tendons,
bones and ears
• Example:
Without the kinesthetic sense
you could not touch the button
to make copies of your buttocks.
Vestibular Sense
• Enables you to sense
your body position
and balance
• Located in our
semicircular canals
in our ears.
• Example:
Pain
• Biological Influences
– Noiceptors – sensory receptors that detect
hurtful temperatures, pressure or chemicals
– Gate-control theory*
– Endorphins
– Phantom limb sensations
– Tinnitus
• Psychological influences
– Distraction
– Memory of Pain – peak pain, end pain
• Socio Cultural Influences
– More pain when others experience pain
– Mirror neurons that empathize with others pain
Gate Control Theory
• Gate Control Theory – spinal cord
contains a “gate” that blocks pain signals
or allows them to pass through to the
brain
• Example:
Taste
• Sweet, sour, salty and bitter
–Umami
• Taste buds
–Chemical
sense
• Age and taste
Taste
• Bumps on our tongue
are called papillae.
• Taste buds are
located on the
papillae 200+ each
containing a pore.
• Pore – 50-100 taste
receptor cells that
sense food molecules
Sensory Interaction
• Sensory interaction –
some senses influence
others
• Examples:
Jello in the shape of a brain
looks so unappetizing, it tastes
terrible too
McGurk Effect – seeing mouth
movements for ga, but hearing
ha, we may perceive da
(saying one syllable, while hearing
another, you perceive a third)
• Olfaction
Smell
– Chemical sense
– Olfactory receptors - odor
molecules fit into receptors like a
lock and key located in the olfactory
bulb
– Olfactory bulb – transmits smell from
the nose to the brain
– Olfactory nerve – sends neural
messages to from the olfactory bulb
directly to the olfactory cortex in
the brain bypassing the thalamus
– Olfactory cortex – receives
information from the olfactory bulb
• Conscious awareness of odors
• Identification of odors
– Hotline between olfactory cortex and
limbic system (memory and emotion)
Smell (olfaction)
Smell and age