Exam 2 Material: Hearing Flashcards
(114 cards)
1
Q
What is sound created by?
A
pressure waves in the air
2
Q
amplitude
A
loudness, expressed in decibels (dB)
3
Q
How many decibels is a normal conversation?
A
65dB
4
Q
Over how many decibels can you start to get hearing loss?
A
85dB
5
Q
Frequency
A
the number of cycles per second of vibration, measured in Hertz (Hz)
it is perceived as pitch
6
Q
What is the range of human hearing in Hertz?
A
20-20,000Hz depending on age
7
Q
Sound is _______ into neural activity known as ______
A
transduced
action potentials
8
Q
parts of the external ear
A
pinna and ear canal
9
Q
pinna
A
collects sound waves and pushes them into the ear canal
10
Q
ear canal
A
auditory canal
11
Q
What does the shape of the ear do?
A
it modifies the character of sound
helps to pin point where the sound is coming from
12
Q
function of the external ear
A
funnel sound
13
Q
function of the middle ear
A
concentrate sound energy
14
Q
What are the 3 ossicles in the inner ear?
A
malleus, incus, stapes
15
Q
What do the ossicles connect?
A
the tympanic membrane (eardrum) to the oval window
16
Q
what happens when sound hits the tympanic membrane?
A
it wiggles back and forth, vibrating through the ossicles
17
Q
what are the 2 muscles in the inner ear?
A
tensor tympani and stapedius
18
Q
tensor tympani
A
attached to the malleus and tympanic membrane
19
Q
stapedius
A
attached to the stapes
20
Q
acoustic reflex
A
when activated, muscles stiffen and reduce the sound’s effects
- ONLY protects against chronic, sustained loud noises
- not gun shots, short loud noises
21
Q
Why does sound not appear as loud anymore overtime?
A
the muscles tighten and hold the ossicles in place so you get less vibrations and sound pressure reaching the inner ear
22
Q
what connects the ear with the rearmost part of the palate (nasal cavity and throat)?
A
eustachian tube
23
Q
function of eustachian tube
A
equalizes pressure on both sides of the eardrum
24
Q
When does the eustachian tube open?
A
when you swallow and with positive pressure (ears pop on an airplane)
yawning, chewing
25
What part of the ear is responsible for turning sound into neural activity (action potential)?
inner ear
| cochlea
26
endolymph
fluid in ear
27
cochlea
coiled structure with 3 parallel canals , only in mammals
28
What are the 3 parallel canals of the cochlea?
scala vestibuli
scala media
scala tympani
29
scala vestibuli
vestibular canal
30
scala media
middle canal
has:
- organ of corti
31
organ of corti
receptor system that converts vibration into neural cavity
32
scala tympani
tympanic canal
33
Hair cells in the organ of corti
embedded in basilar membrane
34
What does a high frequency sound displace?
| and example
the narrow base of the basilar membrane
| ex: crying baby
35
What does a low frequency sound displace?
| and example
the wider apex (at very middle of cochlea)
| ex: stereo bass
36
cilia tips of hair cells are joined by...
tip links
37
describe the mechanically gated ion channels in hair cells and what does this remind you of from other chapters?
cilia movement produces tension of the link which opens an ion channel in the adjacent tip
- like touch receptors (mechanoreceptors)
38
do hair cells fire action potentials?
NO
| - but they depolarize resulting in a receptor potential
39
In hair cells what are the 2 types of sensory cells?
inner hair cells (IHC)
| outer hair cells (OHC)
40
What do IHC do?
signal transduction
| - release glutamate into synapse with vestibulocochlear nerve (CN8)
41
What does OHC do?
amplify and refine cochlea to help discriminate frequencies
42
hyperpolarization causes...
lengthening
43
depolarization causes...
shortening
44
Auditory nerve fibers from IHCs terminate in the
cochlear nuclei (synapse 1)
45
Cochlear nuclei send information to the
superior olivary nuclei (synapse 2)
46
cochlear nuclei relay sound information to what sides of the body
contralateral and ipsilateral superior olivary nuclei
47
What are the 2 divisions of the superior olivary nuclei?
1. lateral superior olive
| 2. Medial superior olive
48
What does the lateral superior olive process?
intensity differences (loud vs. quiet)
49
What does medial superior olive process?
latency differences , but encodes sound by relative activity of the right and left sides
"when is it coming, what did it say"
50
What cues signal sound location
binaural
51
what are the 2 types of binaural cues
1. interaural intensity differences
| 2. interaural latency differences
52
Interaural intensity differences
difference in loudness at the 2 ears
53
interaural latency differences
difference between the 2 ears in the time of arrival of sounds
54
duplex theory
sound localization requires processing f both intensity and latency differences
55
How many synapses are in the auditory pathway
5
56
First synapse in the auditory pathway
auditory nerve fibers from IHCs terminate in the cochlear nuclei
57
Second synapse in auditory pathway
cochlear nuclei send info to the superior olivary nucleu
58
Third synapse in the auditory pathway
superior olivary nuclei pass this info from both ears to the inferior colliculi
59
inferior colliculi
primary auditory centers of the midbrain
60
Fourth synapse in the auditory pathway
outputs of the inferior colliculi go to the medial geniculate nuclei
61
5th synapse of auditory pathway
pathways from here extend to the auditory cortex via internal capsule
62
What do all levels of the auditory pathway have?
tonotopic organization
63
arranged in a map according to the frequencies to which they respond
tonotopic organization
64
Where does brain imaging show the main area of activation is?
primary auditory cortex (A1) on the superior temporal lobes
65
What are the 2 main streams of ho the auditory cortex analyzes complex sounds?
dorsal stream
| ventral stream
66
Dorsal stream
| where and function
parietal lobe
involved in spatial location (Where is sound coming from)
receives info from BOTH ears
67
Ventral stream
| where and function
temporal lobe
what am i hearing
pitch and volume
receives info from ONE ear
68
portion of auditory cortex that first processes music, it is larger in musicians than regular people
Heschl's gyrus
69
amusia
inability to discern tunes
| "tone deaf"
70
all levels of auditory processing have...
tonotropic organization
71
How is tonotropic organization arranged
based on frequencies they respond to
72
Where is the primary auditory cortex (A1) located?
superior temporal lobe and within the lateral (sylvian fissure)
73
Pure tones mostly activate what lobe of the brain?
temporal lobe
74
What areas of the brain do human speech sounds activate
several subcortical regions
75
Speech sound information is relayed to...
Wernicke's area
76
Where is Wernicke's area?
left cerebral hemisphere (junction between temporal and parietal lobes)
77
What is Wernicke's area involved in?
SPOKEN language comprehension
78
What happens if you get damage to Wernicke's area?
Wernicke's aphasia
| - you will not be able to understand what people are saying
79
Why do songs get stuck in your head?
cortical volume of Heschl's gyrus is smaller in people prone to these "earworms"
ALSO frontal lobe smaller in these people
80
hearing loss vs deafness
hearing loss: reduced capacity to interpret sound
| deafness: profound inability to hear (can not hear at all)
81
what can cause hearing loss?
aging, physical trauma
82
3 main causes of hearing loss and deafness
| types of deafness
conduction deafness
sensorineural deafness
central deafness
83
disorders to the outer or middle ear that prevent sounds from reaching the cochlea
- not getting to hair cells of cochlea
- ossicle damage, ruptured ear drum, physical blockage
conduction deafness
84
deafness originates from cochlear or auditory nerve lesions
| - damaged hair cells due to chronic loud noise
sensorineural deafness
85
deafness caused by brain lesions such as strokes
- cochlea is still intact
- damage to temporal lobe (brain injury), not reaching the primary auditory cortex (A1)
central deafness
86
3 ways to restore hearing defecits
hearing aids
teflon prosthetics
cochlear implants
87
use electronic amplification to deliver louder sounds to the impaired (but still functional) auditory system
hearing aids
88
what can fused ossicles be replaced with
| - fused so they cannot vibrate in response to noise
teflon prosthetics
89
used to treat deafness due to hair cell loss
| - electrical currents stimulate auditory nerve
cochlear implants
90
Functions of vestibular system
detects position and movement of the head
- helps maintain posture and balance
- lets you know if moving up/down, forward/backwards
- leads to motion sickness
91
what can people who get motion sickness blame?
faulty vestibular system
92
Where is the vestibula labyrinth located?
in inner ear next to cochlea
93
semicircular canals
3 fluid-filled tubes in different planes detect rotation
- nodding up and down
- tilting left and right
- shaking side to side
94
otolith organs
fluid-filled sacs that respond to movement
| forward/backwards
95
Movement of head pushes _____ through canals to the ______
endolymph
| ampulla
96
The ampulla has hair cells that are surrounded by....
gelatinous cupula coating
97
What happens when endolymph moves?
it bends/distorts the cupula opening K+ ion channels
| depolarization opens Ca2+ channels and glutamate is released into synapse with the vestibulocochlear nerve
98
what cranial nerve is the vestibulocochlear nerve?
CN8
99
Otolith organs respond to movement
| what is responsible for horizontal movement?
utricle
100
otolith organs respond to movement
| what is responsible for vertical movement?
saccule
101
otolith organs have hair cells embedded in the macula covered in a gelatinous mass with _____ on top
otoconia
102
otoconia
tiny calcium carbonate crystals
103
What happens when you get the added weight of the otoconia?
It drags the hair cells when the head changes position, opening the K+ channels depolarizing leading to Ca2+ influx and glutamate release into vestibulocochlear nerve
104
What is Vertigo caused by?
when otoconia breaks off and migrates into the semicircular canals
- bumping crystals when moving tells canals head is moving even when it is not moving, get uncontrolled extra movement as if rotating when not
- get dizziness
105
What neurotransmitter do hair cells release into the synapse with the vestibulocochlear nerve
glutamate
106
Where are vestibulocochlear nerve cell bodies located
outside CNS in vestibular ganglion
107
Axons enter the brainstem and synapse on how many vestibular nuclei?
4
108
What brain regions do the axons of the vestibular nuclei cell bodies extend to?
brainstem (spinal cord, cerebellum, midbrain )
109
cerebellum
balance and gait control
110
midbrain (tectum)
eye movement
111
spinal cord
postural/balance movements
112
How do you get motion sickness?
contradicting inputs from the vestibular system and sensory inputs to brain
113
Scenarios that lead to motion sickness (4)
- actual vs expected motion
- motion that is felt but not seen
- motion seen but not felt
- motion perceived by both systems but do not match perfectly
114
Role of area postrema in motion sickness?
brain believes youmust be hallucinating, triggers vomiting
| - gets "this does not match" signal, ingested a toxin
