L8-L10 Flashcards

1
Q

What does an audibility curve depict?

A

absolute threshold for hearing as a function of frequency

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2
Q

Audibility threshold

A

the lowest sound pressure level that can be reliably detected across the frequency range of human hearing (20-20000 Hz)

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3
Q

Audiometer

A

an instrument used to measure the absolute threshold (dB) for pure tones of different frequencies

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4
Q

What 2 kinds of sounds stimulate the cochlea?

A

air-conducted sounds (e.g. headphones) and bone-conducted sounds (e.g. vibration of skull)

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5
Q

2 ways in which loudness perception is different from intensity

A

(1) different sound pressure levels can result in the same loudness perception depending on frequency; (2) loudness increases with duration of sound (up to 200ms) with intensity held constant

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6
Q

Temporal integration

A

the perception of loudness depends on the summation of energy over a brief, but noticeable, period of time (100-200ms)

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7
Q

3 methods used to study loudness perception

A

loudness matching, loudness scaling, and loudness discrimination experiments

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8
Q

Psychoacoustics

A

branch of psychophysics that studies the psychological correlates of the physical dimensions of sound

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9
Q

Task performed in loudness matching

A

adjust the intensity of comparison tones to match the loudness of a 1000 Hz standard tone of a certain intensity, resulting in an equal loudness contour

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10
Q

What does an equal-loudness contour depict?

A

the sound pressure level necessary for comparison tones between 20-20000 Hz to match the loudness of a 1000 Hz standard tone of a fixed sound pressure level (indicated by the number on each curve)

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11
Q

Phon

A

unit of loudness level for pure tones obtained from matching experiments; sound pressure level of an equally loud 1000Hz pure tone

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12
Q

Task performed in loudness scaling

A

adjust the intensity of a 1000Hz, 40dB tone to be twice as loud (2 sones), half as loud, etc.

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13
Q

Sone

A

unit of loudness from scaling experiments

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14
Q

What’s the JND for loudness?

A

a 1-2 dB increase in intensity is required to be able to notice any increase in loudness

loudness increases more slowly than intensity!

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15
Q

What is pitch perception related to in pure tones and complex tones?

A

frequency of pure tones and fundamental frequency of complex tones

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16
Q

Frequency range of human hearing

A

20-20000 Hz (can’t hear below or above regardless of intensity)

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17
Q

At what frequency range is pitch discrimination good?

A

low frequencies; JND increases as standard frequency increases

therefore, place theory of frequency coding can’t entirely explain pitch perception

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18
Q

Masking

A

measures the absolute threshold for detecting a pure tone in the presence of masking noise of varying bandwidth (range of frequencies with equal amplitude)

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19
Q

Why do psychoacousticians use masking experiments?

A

to investigate frequency selectivity

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20
Q

Critical bandwidth

A

bandwidth beyond which adding more frequencies to the masking noise does not raise the absolute threshold any further

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21
Q

General finding on critical bandwidths

A

lower frequency test tones have smaller critical bandwidths

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22
Q

What is the interpretation of critical bandwidths?

A

reveals the frequency tuning of sets of auditory neurons used to detect the test tone; frequencies outside the bandwidth may stimulate a different set of neurons

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23
Q

Upward spread of masking

A

masking effect is asymmetrical; masking frequencies lower than the test tone are more effective

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24
Q

Task performed in psychophysical tuning curves

A

adjust masking tone intensity until the low dB test tone (1 of 6 frequencies) that occur at some point during the masking tone is just detectable

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25
When does the greatest masking effect occur?
hardest to hear the test tone when its frequency and that of the masking tone are equal
26
Ohm's acoustical law
separation of sound components by auditory system based on Fourier analysis
27
Conductive hearing loss
disturbance in mechanical transmission of sound through outer or middle ear that usually results in uniform loss at all frequencies
28
3 causes of conductive hearing loss
injured ear drum, infections (otitis media), abnormal growth of ossicles (otosclerosis)
29
What kind of sound can be heard with conductive hearing loss?
bond-conducted sounds (via inner ear) but not air-conducted sounds
30
Otitis media
middle ear fills with mucus during ear infections
31
Sensorineural hearing loss
most common and serious form usually caused by cochlear or auditory nerve damage
32
What kind of sounds can be heard with sensorineural hearing loss?
cannot hear bone-conducted or air-conducted sounds
33
Cochlear damage in sensorineural hearing loss
characterized by decreased activity or injury of hair cells and is usually restricted to certain frequencies
34
Causes of cochlear damage in sensorineural hearing loss
infections, genetic disease, ototoxic drugs, aging, exposure to sudden or prolonged loud sound
35
Auditory nerve damage in sensorineural hearing loss
type of retrocochlear dysfunction (occurs beyond cochlea) that is often unilateral and caused by tumors
36
Presbycusis
age-related hearing loss that is usually sensorineural and bilateral; loss begins at high frequencies then low frequencies with advancing age
37
What damage in the ear causes presbycusis?
wearing out of hair cells with age and degeneration of stria vascularis (metabolic hearing loss)
38
Metabolic hearing loss
stria vascularis loses its ability to perform its job of bathing the cochlear partition with nutrients and ions, which reduces hair cell activity
39
What is used to assess hearing loss?
audiogram (normal threshold at 0 and elevated threshold indicating hearing loss)
40
Acoustic reflex
prolonged loud sounds cause the bilateral contraction of the tensor tympani and stapedius muscles regardless of which ear is stimulated
41
Acoustic reflex threshold
softest sound that elicits the acoustic reflex; normally 70-100 dB
42
Ipsilateral acoustic reflex
right ear stimulation causes right reflex; left ear stimulation causes left reflex
43
Contralateral acoustic reflex
right ear stimulation causes left reflex; left ear stimulation causes right reflex
44
What do the status of ipsilateral and contralateral acoustic reflexes indicate?
site of damage in the ear
45
Acoustic reflex affected by middle or inner ear problem
if ipsilateral reflex is affected in one ear, so are contralateral reflexes
46
Acoustic reflex affected by retrocochlear dysfunction
different ipsilateral and contralateral reflex patterns
47
Function of hearing aids
selective amplification for frequencies with greatest loss; compresses intensity differences to keep high intensities at comfortable level
48
3 kinds of hearing aids
behind-the-ear, in-the-ear, and bone-anchored hearing aids
49
When are behind-the-ear hearing aids used?
when some inner ear function remains
50
When are in-the-ear hearing aids used?
mild to moderate hearing loss
51
When are bone-anchored hearing aids used?
conductive loss or severe unilateral sensorineural loss; surgically implanted behind the damaged ear
52
Surgery for conductive hearing loss
replace ossicles if they are immobilized or graft a tympanic membrane
53
Cochlear implant
transmits sound into electrical signals, which activate electrode arrays that stimulate AN fibers at appropriate positions along the cochlea
54
When are cochlear implants used?
only for severe sensorineural loss
55
When are brainstem implants used?
retrocochlear dysfunction
56
Interaural time difference (ITD)
difference in time between arrivals of sound in one ear vs the other
57
Azimuth vs elevation in sound localization
left/right direction of sound source; up/down position of sound source
58
Which azimuths produce the largest and smallest ITDs?
when sound comes directly from the left or right (90°); when sound comes directly in front of (0°) or behind the head (180°)
59
Interaural level difference (ILD)
intensity difference between ears as a function of azimuth
60
Which azimuths produce the largest and smallest ILDs?
largest intensity difference when sound comes directly from left or right; no intensity difference for sounds directly in front or behind head (reaches ears simultaneously)
61
Why are ILDs only present at high frequencies?
high frequency sound waves bounce off the head, creating a sound shadow, and only some reaches the other ear; low frequency sound waves can pass by the head ## Footnote ILDs only present at frequencies above 1000 Hz
62
Medial superior olive (MSO)
contain neurons that are sensitive to ITDs and fire APs when stimulated by specific lag between left and right ear signals ## Footnote ITDs may create place differences on left and right basilar membranes
63
Lateral superior olive (LSO)
contain neurons that are sensitive to ILDs, which receive both excitatory and inhibitory inputs
64
Which ear do excitatory connections to LSO come from?
ipsilateral ear (originate in the left or right cochlea)
65
Which ear do inhibitory connections to LSO come from?
contralateral ear via the medial nucleus of the trapezoid body (MNTB)
66
Cone of confusion
region of positions in space where all sounds produce the same time and intensity differences (i.e. ITD and ILD are ambiguous)
67
2 ways to resolve ambiguous time and intensity differences in sound
horizontal rotational head movements; shape of the pinna (highly ear-specific input)
68
Directional transfer function (DTF)
graph showing the intensity of sounds over a range of frequencies that arrive at each ear from different locations in space (azimuth and elevation)
69
2 components of the vestibular sense
perception of spatial orientation and reflexive vestibular responses
70
3 sensory modalities of our perception of spatial orientation
angular motion, linear motion, and tilt (transduce different kinds of energy)
71
Examples of reflexive vestibular responses
eye rotation, balance, autonomic responses (motion sickness, blood pressure)
72
Graviception
ability to sense the relative orientation of gravity (i.e. tilt sensation)
73
2 types of vestibular sense organs
semicircular canals and otolith organs in the inner ear
74
Which vestibular receptors do changes in acceleration (rate of head motion) stimulate?
semicircular canals (angular acceleration) and otolith organs (linear acceleration)
75
Which vestibular receptors do changes in head position with respect to gravity stimulate?
otolith organs (e.g. head tilt)
76
2 qualities of vestibular stimuli
amplitude (velocity or magnitude of displacement of head movement) and direction
77
3 translation directions for linear motion
positive x-axis translation (forward and backward); positive y-axis translation (left and right); positive z-axis translation (up and down)
78
3 rotational directions
roll, pitch, yaw
79
Roll rotation ## Footnote Clue: r
head stays in the frontal/coronal plane and rotates around the x-axis; "comme ci, comme ca" nods
80
Pitch rotation
head stays in the medial/sagittal plane and rotates around y-axis; "yes" nods
81
Yaw rotation
head stays in the transverse/axial plane and rotates around z-axis; "no" motion
82
2 tilt directions (with respect to gravity)
roll tilt and pitch tilt (no yaw tilt because movement is aligned with gravity)
83
Which receptors does rotary acceleration stimulate in the semicircular canal?
receptors in the ampulla of each semicircular canal (anterior, posterior, and horizontal)
84
Ampulla
swelling at the base of each semicircular canal that includes the cupula, crista, and hair cells, where transduction occurs
85
Receptor potential
slow change in membrane voltage that is proportional to stereocilia bending
86
Which semicircular canal is most sensitive to yaw turns?
horizontal canal (z-axis)
87
Push-pull response in semicircular canals
yaw motion to the right depolarizes hair cells in the right horizontal canal and hyperpolarizes hair cells in the left horizontal canal, which increases firing rate in the right vestibular nerve and decreases firing rate in the left vestibular nerve
88
What are the two otolith organs?
utricle and saccule, which both contain macula where sensory transduction occurs
89
How many hair cells in the utricular macula vs saccular macula?
30000 hair cells (horizontal); 16000 hair cells (vertical)
90
Push-pull response in otolithic organs
tilt or linear acceleration that maximally excites hair cells (and vestibular nerve fiber) on one side of the striola will maximally inhibit those on the opposite side
91
Oculogyral illusion
visual disorientation and apparent movement followed by rapid body spins; cupula deflected in opposite direction before returning to resting position
92
Oculogravic illusion
apparent backward tilt and visual elevation experienced during forward body acceleration; macula can't distinguish between displacements due to horizontal acceleration or to static head tilt