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Chapter 8

PSYB65H3 Chapter Notes - Chapter 8: Echolalia, Frontal Lobe, Oval Window


Department
Psychology
Course Code
PSYB65H3
Professor
Ted Petit
Chapter
8

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Chapter 8
Module 8.1
THE AUDITORY SYSTEM
THE PROPERTIES OF SOUND
o Frequency: is the physical dimension
Refers to the RATE OF VIBRATION
Measured in Hertz (Hz)
Humans can only hear between 20-20000 Hz
Frequency is different from speed sounds travels at around 340 meters/second
Pitch: the perceptual dimension of frequency
The higher the frequency, the higher the pitch
o Amplitude: the physical dimension
Waves of different intensities differ in the degree to which the high point and the low
point differ from each other.
Measures in decibels (dB)
Conversational speech tends to occur at 40-60 dB
Loudness: the perceptual dimension
The bigger the difference between the high and low parts of the wave, the
louder the sound
o Complexity: the physical dimension
Most sounds are composed of a wide variety of frequencies and intensities (pitch and
loudness)
Along with the intended frequency (the fundamental frequency) an instrument usually
produces overtone too (frequencies higher than but related to the fundamental
frequency)
Timbre: the perceptual dimension
o Sounds are changing at all times and both our ears hear different things but still all these
information are effortlessly integrated into an unitary perception.
THE EAR
o Transduction detecting and amplifying subtle vibrations in the air and transforming these
into neural signals
o The pathway of sound:
o The outer ear
Pinna and external ear canal catch and amplify vibrations
o The middle ear
Ear drum, ossicles (Malleus, incus and stapes) and oval window transduced into
mechanical energy
o The inner ear
Mechanical to neural energy
The cochlea and the components Organ of Corti
Inner hair cells receptors of the auditory system
Pinna
Audito
ry
meatu
s
ear
canal
ear
drum
ossicle
s
oval
windo
w
cochlea
basilar
or
tectori
al
membr
ane
hair
cells

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o Cilia
Arranged in order of height
When the cilia moves in the direction of the tallest cilium, fibres
within the cilia are stretched increased firing in the axons of the
cochlea nerves
When the cilia moves in the opposite direction low firing rate
Outer hair cells modulatory role; help tune the cochlea through the
contractions and relaxations
WHAT MAKES THE CILIA MOVE?
The hair cells are located along the basilar membrane and adjacent to the hair
cells is the tectorial membrane
The sound waves causes the 2 membranes to flex and this movement cause the
cochlear fluid to flow past the cilia, bending them.
Different sections of cochlea responds to different frequencies referred to as
tonotopic frequency specific sensory organization
o Part of basilar membrane closest to the oval window higher frequency
o Part near to the apex lower frequency
AUDITORY PATHWAYS
o Axons from the cranial nerve form a branch of the eighth cranial nerve, which synapses on the
ipsilateral cochlear nuclei.
o Cochlear nuclei Superior olivesinferior collicus Medial Geniculate nucleus of the
hypothalamus primary auditory cortex
AUDITORY CORTEX
o Neurons in the auditory cortex is also arranged in tonotpic manner
The columns at the anterior region high frequency
The columns at the posterior regions low frequency
o Secondary auditory cortex areas immediately adjacent to the primary also tonotopic
MODULE 8.2
LANGUAGE SYSTEMS IN THE BRAIN
o MODELS OF SPOKEN LANGUAGE
o 3 distinct ones
“Broca’s Area”
The third gyri on the left frontal lobe
Broca said it was an unitary function only one area involved
“Wernicke’s Area”
Left temporal lobe
Wernicke said 2 areas were involved; one for output and one for input
Also proposed that these 2 centres will need to be connected for
communication ARCUATE FASCICULUS
Wernicke-Lichtheim-Geschwind model
Incorporated the angular gyrus that is located at the junction between occipital,
temporal and parietal lobe and it provides a basis for visual language.
Explains spontaneous speech accessing the mappings of sounds to meaning in
Wernicke’s area via arcuate fasciculus Broca’s area
Account for processing of visual language information
o Perceived by the visual system angular gyrus Wernicke’s area
LIMITATIONS:
o Oversimplification of the visual language processing and omission
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