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THE AUDITORY SYSTEM
SENSE OF HEARING
THE AUDITORY SYSTEM
Mechanoreception: detection of vibration, perceived as
hearing
Stimulus: sound waves
Sense organ: ears
Function: hearing
Auditory transduction: transforms sound waves into
electrochemical impulses that the brain can interpret
SOUND WAVE PROPERTIES
Sound has 3 characteristics:
1. Wavelength: frequency (determines pitch)
• longer = lower frequency = lower pitch
• shorter = higher frequency = higher pitch
• measured in hertz = Hz
2. Wave amplitude: intensity (determines loudness)
• shorter = less intensity = quieter
• taller= more intensity = louder
• measured in decibels = dB
• roughly every 10 dB doubles loudness
3. Purity: quality (determines timbre/tone saturation)
• uniqueness of sound
PARTS OF THE EAR
Outer ear – air conduction
 Pinna
 Auditory canal
Middle ear – bone conduction
 Eardrum (tympanic membrane)
 Ossicles
 Hammer (malleus), anvil (incus), stirrup (stapes)
Inner ear – fluid conduction
 Oval window
 Cochlea
 Basilar membrane and hair cells
 Semicircular canals
 Vestibular sacs
 Auditory nerve
PITCH PERCEPTION
Place Theory
States that each frequency
produces vibrations at a
particular spot on the basilar
membrane.
Location
Explains high pitched
sounds
Frequency Theory
States that the perception of
a sound's frequency depends
on how often the auditory
nerve fires.
Neural impulses
Explains low pitched sounds
VOLLEY PRINCIPLE
Modification of frequency theory stating that a cluster of
nerve cells can fire neural impulses in rapid succession,
producing a volley of impulses.
Fixes limitations of frequency theory
AUDITORY LOCALIZATION
We have two ears
Sounds may reach one ear faster than the other ear
Or sounds may be louder in one ear than another
This let’s us locate the sound
Our head acts as a “shadow”
Sound shadow
Can not localize if directly in front, back or above
HEARING LOSS
Conductive Hearing Loss
Sensorineural Hearing Loss
hearing loss occurs when there is
Hearing loss occurs when sound is
damage to the inner ear (cochlea), or
not conducted efficiently through
to the nerve pathways from the inner
the outer ear canal to the eardrum
ear to the brain.
and the tiny bones (ossicles) of
Most of the time, cannot be
the middle ear.
medically or surgically corrected.
Usually involves a reduction in
most common type of permanent
sound level or the ability to hear
hearing loss.
faint sounds.
reduces the ability to hear faint
Can often be corrected medically or
sounds.
surgically
Caused by damage to the cochlea or
to the auditory nerve
Caused by damage to the parts of
the ear that connect to the
cochleaHearing Loss
Mixed
HEARING LOSS
THE TACTILE SYSTEM
SENSE OF TOUCH
THE TACTILE SYSTEM
Mechanoreception: detection of pressure, perceived as touch
Thermoreception: detection of temperature; perceived as warm
and cold
Nociceptors: detection of noxious stimuli; perceived as pain
Stimulus: mechanical, thermal, and chemical energy
Sense organ: skin
Function: touching
Tactile transduction: transforms mechanical, thermal, and
chemical energy on the skin into electrochemical impulses that the
brain can interpret
THE SENSORY SYSTEM
 Three kinds of receptors:
 touch
 temperature
 warm
 cold
 pain
 Four distinct skin senses:
 pressure
 warmth
 cold
 pain
 Extreme heat & extreme cold are THE SAME!
PAIN
Pain tells the body that something has gone wrong.
Congenital Insensitivity to Pain (CIP): A rare disease in which
the afflicted person feels no pain.
no sense of smell
unable to sweat
sodium channel mutation
PAIN PATHWAYS
Two pain pathways:
fast
 A-delta fibers
• less than 1 second
• myelinated
slow
 C fibers
• a couple of seconds
• unmyelinated
PAIN PERCEPTION
Gate Control Theory:
creates neural blockage
Studied by Ronald Melzack & Patricia Wall (1965)
ENDORPHINS
Neurotransmitters
natural opiate
morphine-like painkillers
THE GUSTATORY SYSTEM
SENSE OF TASTE
THE GUSTATORY SYSTEM
Chemoreception: detection of chemical stimuli, perceived as
taste
Stimulus: soluble chemicals
Sense organ: tongue
Function: tasting
Gustatory transduction: transforms soluble chemicals in
food into electrochemical impulses that the brain can interpret
THE OLFACTORY SYSTEM
SENSE OF SMELL
THE OLFACTORY SYSTEM
Chemoreception: detection of chemical stimuli, perceived as
smell
Stimulus: volatile chemicals
Sense organ: nose
Function: smelling
Olfactory transduction: transforms volatile chemicals in the
air into electrochemical impulses that the brain can interpret
THE KINESTHETIC SYSTEM
SENSE OF POSITION & MOVEMENT
THE KINESTHETIC SYSTEM
Mechanoreception: detection of vibration, perceived as
hearing
Stimulus: sound waves
Sense organ: ears
Function: hearing
Auditory transduction: transforms sound waves into
electrochemical impulses that the brain can interpret
THE VESTIBULAR SYSTEM
SENSE OF BALABNCE & MOVEMENT
THE VESTIBULAR SYSTEM
Mechanoreception: detection of vibration, perceived as
hearing
Stimulus: sound waves
Sense organ: ears
Function: hearing
Auditory transduction: transforms sound waves into
electrochemical impulses that the brain can interpret
THE
th
6
SENSE
EXTRASENSORY PERCEPTION (ESP)
PARAPSYCHOLOGY
The study of paranormal phenomena.
Over 75 years of research
No evidence of paranormal phenomena exists
EXTRASENSORY PERCEPTION
Perception without sensory input.
Energy source?
Sensory receptors?
Paranormal phenomena include:
Astrological predictions, psychic healing, communication
with the dead, out-of-body experiences, telepathy,
clairvoyance, and precognition.
TYPES OF ESP
Telepathy: Mind-to-mind communication. One person
sending thoughts and the other receiving them.
Clairvoyance: Perception of remote events.
Precognition: Perceiving future events.