Lecture 3: Audition Flashcards
1
Q
What are the 4 major features of sound?
A
- waveform
- phase
- amplitude
- frequency
2
Q
Perception of sound corresponds to what 2 things?
A
loudness and pitch
3
Q
Pressure amplitude is responsible for what?
A
loudness
4
Q
Frequency is responsible for what?
A
pitch
5
Q
What is compression/condensation?
A
when neighboring air molecules are pushed together
6
Q
What are pure tones?
A
sounds produced by objects vibrating in simple harmonic motion
7
Q
What does wave form project?
A
how projection of sound moves in time and space
8
Q
What is sound wave propagation?
A
sound wave moves through the air as each particle sets its neighbor in motion
9
Q
What is the sinusoidal function?
A
simple harmonic motion that generates a sine wave
10
Q
Low frequency is related to what type of vibration?
A
slow
11
Q
High frequency is related to what type of vibration?
A
rapid
12
Q
What is a phase shift?
A
relationship between 2 sine waves with the same frequency that are displaced in time
13
Q
What is the range of human hearing?
A
20-20000 Hz
14
Q
What is the range for uncomfortable loudness?
A
100 dB
15
Q
At what range would humans feel pain?
A
120-140 dB
16
Q
At what range do humans have the best hearing?
A
6000-8000 Hz
17
Q
What shape of the extrernal ear contributes to what?
A
- protection
- sound gathering providing a high frequency boost >3000 Hz
- sound localization and elevation detection
- alters effective spectrum of sound
17
Q
What shape of the extrernal ear contributes to what?
A
- protection
- sound gathering providing a high frequency boost >3000 Hz
- sound localization and elevation detection
- alters effective spectrum of sound
18
Q
Where does the middle ear start?
A
tympanic membrane/eardrum
19
Q
What is the middle ear space?
A
malleus, incus, stapes which attach to the oval window
20
Q
What is the smallest bone in the body?
A
stapes
21
Q
What is impedance matching?
A
when sound goes from air to water, they reflect and undergo a 30 dB loss in intensity
22
Q
What is the most helpful impedance matching?
A
area advantage
23
Q
What are the 3 types of impedance matching?
A
- area advantage: 27 dB
- ossicular lever action: 1.3 dB
- curved membrane buckling mechanism: 6 dB
24
What is the inner ear a site for?
transduction of sound pressure waves to action potential
25
What is the vestibular portion of the inner ear?
cochlea
26
Where does actual hearing begin?
27
What are the 3 parts of the cochlea?
* scala vestibuli (perilymph)
* scala media (endolymph)
* scala tympani (perilymph)
28
What are the characteristics of the scala vestibuli?
* located at the top
* similar to extracellular fluid
29
What are the characteristics of the scala media?
* located in the middle
* has its own fluid
30
What are the characteristics of the scala tympani?
shares fluid with vestibuli
31
What is tonotopic organization?
organized with purpose to recognize different frequencies
32
In a "stiffness gradient", high frequencies cause vibrations where?
near the base
33
In a "stiffness gradient", low frequencies cause vibrations where?
near the apex
34
What is the organ of corti comprised of?
sensory hair cells and other supporting cells
35
How many rows are there of inner and outer hair cells?
* 3 rows of outer
* 1 row of inner
36
Where does the organ of corti sit?
in the basilar membrane
37
Is it inner or outer hair cells that are actually able to hear?
inner
38
What are inner hair cells?
sensory cells that send info to 8th nerve
39
What are outer hair cells?
* amplifiers
* receive efferent innerv. that can modify sound
40
What are the steps involved in the activation of hair cells?
1. tympanic membrane set into vibration by sound
2. stapes footplate moves in and out of oval window
3. pressure pushed into cochlea; fluid begins to move
4. basilar membrane moves up and down
5. hair cells become excited
41
How are hair cells excited?
by "shear force" generated between reticular lamina and tectorial membrane
42
The "shear force" causes stereocilia to bend in what direction?
lateral
43
When the basilar membrane moves up, what does the "shear force" do?
pushes hair cells
44
When the basilar membrane moves up, what does the "shear force" do?
pushes hair cells
45
When the basilar membrane moves down, what does the "shear force" do?
pulls hair cells backwards
46
What are stereocilia connected by?
tip link structure
47
What are the steps of the mechanotransduction process?
1. K+ current depolarizes cell and opens voltage dependent Ca++ channels leading to transmitter release
2. Ca++ dependent K+ channels open -> repolarization
48
What are the 2 proteins wihtin the tip links to move hair hair cells and allow move K+ to flow into the cell?
myosin and actin
49
When do the stereocilia move in a medial direction?
when the basilar membrane moves down
50
How much OHC are there total?
about 12,000
51
How much IHC are there total?
about 3,000
52
The motility in OHC is due to what protein?
prestin
53
During the excitatory phase, does the cell shorten or elongate?
shorten
54
During the opposite phase, does the cell shorten or elongate?
elongate
55
What activates the auditory neuron?
neurotransmitter release at base if IHC
56
IHC transduces mechanical vibration into what?
neural signals
57
How do OHCs improve hearing?
amplify vibration of basilar membrane
58
Type 1 and type 2 fibers are apart of what nerve?
8th cranial nerve (auditory nerve)
59
What is the central auditory pathway?
auditory nerve -> cochlear nucleus -> sup. olivary complex -> inf. colliculus -> med. geniculate body -> auditory cortex
60
What is the only uncrossed pathway?
cochlear nucleus
61
The cochlear nucleus has what type of signaling?
monoaural
62
What is monoaural signaling?
* right ear = right cochlear nucleus
* left ear= left cochlear nucleus
63
What is the 1st auditory nucleus?
cochlear nucleus
64
Where is the cochlear nucleus located?
medulla
65
What are the 2 functions of the cochlear nucleus?
1. relays signals to sup. olivary complex
2. analyzes complex signals and sends info to inf. colliculus
66
Where is the superior olivary complex located?
pons
67
What type of signal does the sup. olivary complex have?
binaural: receive info from both ears
68
What are the 2 nuclei involved in sound localization and have maps of spatial location?
* lat. superior olive
* med. superior olive
69
What are the characteristics of the lat. sup. olive?
* localization of high frequency sounds
* using interaural level differences
70
What are the characteristics of the med. sup. olive?
* localization of low frequency sounds
* using interaural time differences
71
Where is the inf. colliculus located?
in the midbrain
72
What is the function of the inf. colliculus?
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combines spatial info. from sup. olivary complex with info about complex sounds from cochlear nucleus
73
The inf. colliculus is involved with what type of reflexes?
auditory
74
What part of the central auditory pathway is involved with head-turn responses?
inf. colliculus
75
What part of the centrla auditory pathway coordinates auditory and visual responses?
inf. colliculus
76
Where is the medial geniculate body located?
thalamus (gateway of the cortex)
77
What is the function of the medial geniculate body?
relay station for info. going up to or down from the auditroy complex
78
The med. geniculate body projects to what complex?
primary auditory (A1)
79
Where do secondary projection from A1 project to?
secondary auditory complex (A2)
80
Where is the auditory cortex initially processed?
temporal lobe
81
About how many auditory nerve fibers are in humans?
1,600
82
Efferent innervation of hair cells are part of what that descends from the sup. olivary complex to the cochlea?
olivocochlear bundle
83
Are inner or outer hair cells associated with indirect efferents when they're turned on?
inner
84
Are inner or outer hair cells associated with direct efferents when they're turned off?
outer
85
What is the uncrossed olivocochlear bundle?
LSO -> inner hair cells on same side
86
What is the crossed olivocochlear bundle?
MSO -> outer hair cells on opposite side
87
The human ear is most sensitive to sounds at which of the following frequencies?
A. 150 Hz
B. 1,500 Hz
C. 3,500 Hz
D. 7,500 Hz
C
88
A 21-year-old wrestler presents to his Otorhinolaryngologist (ENT) following a severe injury to the right ear which has caused difficulty hearing. The ENT believes the impact may have altered the patient’s ability to match impedance. If so, which of the following structures was likely damaged?
A. Pinna
B. Tympanic Membrane
C. Scala Media
D. Organ of Corti
B
89
Outer hair Cells (OHC) play an important role in the amplification of sound by altering its length during periods of excitation and inhibition. Which of the following proteins is responsible for these changes?
A. Prestin
B. Actin
C. Myosin
D. Tip Links
A
90
Inner hair cells (IHC) transduce mechanical vibrations into neural signals via which of the following cranial nerves?
A. CN IV
B. CN V
C. CN VII
D. CN VIII
D
91
A 43-year-old man presents to the ED following strange neurological symptoms likely associated with a stroke. If MRI confirms a lesion in the Lateral Superior Olive (LSO), which of the following would likely be impacted?
A. Ability to localize high frequency sounds using sound level differences
B. Ability to localize low frequency sounds using time differences
C. Ability to localize high frequency sounds using time differences
D. Ability to localize low frequency sounds using sound level differences
A
