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Lecture 5

PSYC 2000 Lecture Notes - Lecture 5: Cochlea, Umami, Parietal Lobe

Course Code
PSYC 2000

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Hearing/The Ear
As we get older the ability to pick up high frequency noises diminishes
Stimulus input sound waves
oSound waves are vibrations of the molecules of the air that surround us
oAcoustical transduction- conversion of sound waves into neural impulses in the hair cells
of the inner ear
Characteristics of Sound
oPitch –determined by the wavelength( peak of one wave to the peak of another) or
frequency (low ,medium, or high)
Analogous to the hue of colors
The pitch of a sound is based on what property of the sound wave
Measured in hertz
oVolume (loudness)
Determined by the amplitude or the complexity (richness) of the tone of the
The lower the amplitude the softer the sound
Amplitude is measured in decibels (DB)
Around 85 DB is where it becomes dangerous for hearing
The volume of a sound is based on what property of blah blah
The quality of the tone distinctive of a particular singing voice or musical
Outer ear: consists of pinna that collects & tunnels sounds
oEardrum vibrates when sound waves hit
Middle ear : chamber between eardrum and cochlea
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Theories of Hearing: Pitch Perception
oPlace Theory: different sound waves stimulate the basilar membrane at
diff, specific places resulting in perceived pitch
Explains how e perceive high pitched sound
oFrequency Theory: the rate of firing of nerve impulses traveling up the
auditory nerve matches the frequency of a tone, thus enabling us to sense its
Explains how we perceive
oWolley Principle: different frequencies cause the hair cells (auditory
neurons) to fire in a volley pattern or take turns in firing
Explains how we perceive between moderate to high pitches
(40 Hz-4000 Hz)
Localization of Sounds
oWe have 2 ears, sounds that reach one faster than the other helps us
localize where sound os coming from
Hearing Impairment
oConduction Hearing: sound vibrations cannot be passed from the
eardrum to the cochlea
Caused by damage to the mechanical system that conducts
sound waves to the cochlea
oNerve Hearing: problem lies in inner ear
Hearing Deficits
oOlder ppl tend to hear low frequencies well but suffer hearing loss for
higher frequencies
oThe stimulus Input: Chemicals
Gustatory tastes receptors are clusters of cells which are
responsible for the sense of taste. They are mostly located on the
Gustatory transduction: Conversion of food molecules
o5 Basic Tastes
“Brothy” or “Savory” or Umami
oGustatory Cortex
Located in insular lobe
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Somatic sensory cortex in parietal lobe
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