Lecture 3: Audition Flashcards

1
Q

What are the 4 major features of sound?

A
  • waveform
  • phase
  • amplitude
  • frequency
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2
Q

Perception of sound corresponds to what 2 things?

A

loudness and pitch

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3
Q

Pressure amplitude is responsible for what?

A

loudness

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4
Q

Frequency is responsible for what?

A

pitch

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5
Q

What is compression/condensation?

A

when neighboring air molecules are pushed together

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6
Q

What are pure tones?

A

sounds produced by objects vibrating in simple harmonic motion

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7
Q

What does wave form project?

A

how projection of sound moves in time and space

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8
Q

What is sound wave propagation?

A

sound wave moves through the air as each particle sets its neighbor in motion

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9
Q

What is the sinusoidal function?

A

simple harmonic motion that generates a sine wave

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10
Q

Low frequency is related to what type of vibration?

A

slow

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11
Q

High frequency is related to what type of vibration?

A

rapid

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12
Q

What is a phase shift?

A

relationship between 2 sine waves with the same frequency that are displaced in time

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13
Q

What is the range of human hearing?

A

20-20000 Hz

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14
Q

What is the range for uncomfortable loudness?

A

100 dB

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15
Q

At what range would humans feel pain?

A

120-140 dB

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16
Q

At what range do humans have the best hearing?

A

6000-8000 Hz

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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
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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
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18
Q

Where does the middle ear start?

A

tympanic membrane/eardrum

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19
Q

What is the middle ear space?

A

malleus, incus, stapes which attach to the oval window

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20
Q

What is the smallest bone in the body?

A

stapes

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21
Q

What is impedance matching?

A

when sound goes from air to water, they reflect and undergo a 30 dB loss in intensity

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22
Q

What is the most helpful impedance matching?

A

area advantage

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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
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24
Q

What is the inner ear a site for?

A

transduction of sound pressure waves to action potential

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25
Q

What is the vestibular portion of the inner ear?

A

cochlea

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26
Q

Where does actual hearing begin?

A
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27
Q

What are the 3 parts of the cochlea?

A
  • scala vestibuli (perilymph)
  • scala media (endolymph)
  • scala tympani (perilymph)
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28
Q

What are the characteristics of the scala vestibuli?

A
  • located at the top
  • similar to extracellular fluid
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29
Q

What are the characteristics of the scala media?

A
  • located in the middle
  • has its own fluid
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30
Q

What are the characteristics of the scala tympani?

A

shares fluid with vestibuli

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31
Q

What is tonotopic organization?

A

organized with purpose to recognize different frequencies

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32
Q

In a “stiffness gradient”, high frequencies cause vibrations where?

A

near the base

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33
Q

In a “stiffness gradient”, low frequencies cause vibrations where?

A

near the apex

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34
Q

What is the organ of corti comprised of?

A

sensory hair cells and other supporting cells

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35
Q

How many rows are there of inner and outer hair cells?

A
  • 3 rows of outer
  • 1 row of inner
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36
Q

Where does the organ of corti sit?

A

in the basilar membrane

37
Q

Is it inner or outer hair cells that are actually able to hear?

38
Q

What are inner hair cells?

A

sensory cells that send info to 8th nerve

39
Q

What are outer hair cells?

A
  • amplifiers
  • receive efferent innerv. that can modify sound
40
Q

What are the steps involved in the activation of hair cells?

A
  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
Q

How are hair cells excited?

A

by “shear force” generated between reticular lamina and tectorial membrane

42
Q

The “shear force” causes stereocilia to bend in what direction?

43
Q

When the basilar membrane moves up, what does the “shear force” do?

A

pushes hair cells

44
Q

When the basilar membrane moves up, what does the “shear force” do?

A

pushes hair cells

45
Q

When the basilar membrane moves down, what does the “shear force” do?

A

pulls hair cells backwards

46
Q

What are stereocilia connected by?

A

tip link structure

47
Q

What are the steps of the mechanotransduction process?

A
  1. K+ current depolarizes cell and opens voltage dependent Ca++ channels leading to transmitter release
  2. Ca++ dependent K+ channels open -> repolarization
48
Q

What are the 2 proteins wihtin the tip links to move hair hair cells and allow move K+ to flow into the cell?

A

myosin and actin

49
Q

When do the stereocilia move in a medial direction?

A

when the basilar membrane moves down

50
Q

How much OHC are there total?

A

about 12,000

51
Q

How much IHC are there total?

A

about 3,000

52
Q

The motility in OHC is due to what protein?

53
Q

During the excitatory phase, does the cell shorten or elongate?

54
Q

During the opposite phase, does the cell shorten or elongate?

55
Q

What activates the auditory neuron?

A

neurotransmitter release at base if IHC

56
Q

IHC transduces mechanical vibration into what?

A

neural signals

57
Q

How do OHCs improve hearing?

A

amplify vibration of basilar membrane

58
Q

Type 1 and type 2 fibers are apart of what nerve?

A

8th cranial nerve (auditory nerve)

59
Q

What is the central auditory pathway?

A

auditory nerve -> cochlear nucleus -> sup. olivary complex -> inf. colliculus -> med. geniculate body -> auditory cortex

60
Q

What is the only uncrossed pathway?

A

cochlear nucleus

61
Q

The cochlear nucleus has what type of signaling?

62
Q

What is monoaural signaling?

A
  • right ear = right cochlear nucleus
  • left ear= left cochlear nucleus
63
Q

What is the 1st auditory nucleus?

A

cochlear nucleus

64
Q

Where is the cochlear nucleus located?

65
Q

What are the 2 functions of the cochlear nucleus?

A
  1. relays signals to sup. olivary complex
  2. analyzes complex signals and sends info to inf. colliculus
66
Q

Where is the superior olivary complex located?

67
Q

What type of signal does the sup. olivary complex have?

A

binaural: receive info from both ears

68
Q

What are the 2 nuclei involved in sound localization and have maps of spatial location?

A
  • lat. superior olive
  • med. superior olive
69
Q

What are the characteristics of the lat. sup. olive?

A
  • localization of high frequency sounds
  • using interaural level differences
70
Q

What are the characteristics of the med. sup. olive?

A
  • localization of low frequency sounds
  • using interaural time differences
71
Q

Where is the inf. colliculus located?

A

in the midbrain

72
Q

What is the function of the inf. colliculus?

`

A

combines spatial info. from sup. olivary complex with info about complex sounds from cochlear nucleus

73
Q

The inf. colliculus is involved with what type of reflexes?

74
Q

What part of the central auditory pathway is involved with head-turn responses?

A

inf. colliculus

75
Q

What part of the centrla auditory pathway coordinates auditory and visual responses?

A

inf. colliculus

76
Q

Where is the medial geniculate body located?

A

thalamus (gateway of the cortex)

77
Q

What is the function of the medial geniculate body?

A

relay station for info. going up to or down from the auditroy complex

78
Q

The med. geniculate body projects to what complex?

A

primary auditory (A1)

79
Q

Where do secondary projection from A1 project to?

A

secondary auditory complex (A2)

80
Q

Where is the auditory cortex initially processed?

A

temporal lobe

81
Q

About how many auditory nerve fibers are in humans?

82
Q

Efferent innervation of hair cells are part of what that descends from the sup. olivary complex to the cochlea?

A

olivocochlear bundle

83
Q

Are inner or outer hair cells associated with indirect efferents when they’re turned on?

84
Q

Are inner or outer hair cells associated with direct efferents when they’re turned off?

85
Q

What is the uncrossed olivocochlear bundle?

A

LSO -> inner hair cells on same side

86
Q

What is the crossed olivocochlear bundle?

A

MSO -> outer hair cells on opposite side

87
Q

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

88
Q

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

89
Q

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

90
Q

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

91
Q

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