Hearing Flashcards

1
Q

What is the definition of sound?

A

Pressure waves in the are producing by a vibrating object, which are detected by the auditory system

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2
Q

What is the distal stimulus of sound?

A

Vibrating object

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3
Q

What is the proximal stimulus of sound?

A

Pattern of kinetic energy at the eardrum

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4
Q

What is the phase?

A

Point along the wave measured in degrees

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5
Q

What is the perceptual counterpart to phase?

A

There is no direct perceptual counterpart

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6
Q

What is the amplitude?

A

The displacement of a wave from peak to trough
For large ranges, a logarithmic scale is easier to work with

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7
Q

What is the frequency?

A

The number of sound wave cycles per second in Hz

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8
Q

What is loudness?

A

The perceptual experience of sound intensity
Related to amplitude and sound pressure

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9
Q

What is 1 sone of loudness?

A

100 Hz pure tone at 40 dB

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10
Q

How do we double loudness?

A

Increase dB by 10 dB

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11
Q

What is pitch?

A

Quality of sound ranging from low to high; allows sounds to be ordered on a musical scale
Associated with frequency
Short duration will be heard as a click

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12
Q

What is the fundamental frequency?

A

Lowest frequency in a Fourier spectrum of complex sound wave

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13
Q

What are harmonics?

A

Components of a complex sound having frequencies that are multiples of the fundamental
The number and amplitude of harmonics contribute to the timbre of a sound

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14
Q

What is timbre?

A

Character or nature of a sound
Due to different frequency components produced by a vibrating source stimulus

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15
Q

What is the audibility curve?

A

Describes the absolute threshold for hearing each different frequency

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16
Q

What is the auditory response area?

A

The dynamic range of intensities from threshold to pain

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17
Q

What is the equal loudness curve?

A

Graph of decibel levels of various frequencies that seem equally loud

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18
Q

How do we determine the equal loudness curve?

A

Present standard: 1000 Hz tone at a certain dB level
Adjust intensity of other frequencies to match loudness of standard

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19
Q

What is the equal loudness curve also affected by?

A

Auditory adaptation
Auditory fatigue

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20
Q

What is auditory adaptation?

A

Same sound seems softer if presented for a long time

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21
Q

What is auditory fatigue?

A

Temporary hearing loss due to high intensity sounds

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22
Q

What is the pinna?

A

The ear on the side of your head
Channels certain sound waves into the ear canal

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23
Q

What is the external auditory meatus?

A

The ear canal
Protects the middle and inner ears
Amplifies frequencies 2000 to 5000 Hz via resonance

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24
Q

What is the tympanic membrane?

A

The eardrum
Struck by sound waves and vibrates
Transmits sound to structures in the middle ear

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25
What are the ossicles?
Malleus, incus, stapes; supported by middle-ear muscles Concentrates vibration of the eardrum to the oval window Increases pressure by a 20:1 ratio Acts as levels, increasing vibration
26
What is the eustachian tube?
Equalizes middle ear pressure with outside
27
What are the semicircular canals?
Snail-shaped structure, filled with cochlear fluid, divided into canals -Scala vestibuli -Scala tympani -Scala media
28
What is the scala media formed by?
Basilar membrane and Reissner's membrane
29
What is the tectorial membrane?
Overhangs the basilar membrane, contains 15000 hair cells
30
What are the number of inner hair cells?
3000
31
What is the cell alignment of inner hair cells?
1 row
32
What is the cilia number of inner hair cells?
40-60/cell
33
What is the cilia alignment of inner hair cells?
Straight lines
34
What is the function of inner hair cells?
Sensory
35
What is the number of outer hair cells?
12000
36
What is the cell arrangement of outer hair cells?
3-5 rows
37
What is the cilia number of outer hair cells?
100-120/cell
38
What is the cilia alignment of outer hair cells?
V or W shaped
39
What is the function of outer hair cells?
Supportive
40
What are spatial ganglion cells?
30000 nerve fibers 95% are type 1 = inner hair cell, large, myelinated 5% are type 2 = outer hair cells, small, slow
41
What is the transduction of sound waves like?
Vibration -> eardrum -> ossicles -> oval window -> vestibular canal/cochlear partition -> basilar membrane
42
How do the basilar and tectorial membranes move with respect to each other?
Laterally
43
What does the shearing force do?
Bends the cilia of outer hair cells, which are embedded in the tectorial membrane
44
How are the cilia of inner hair cells bent?
By fluid flow
45
What links the tips of cilia?
Actin fibers
46
What happens when the cilia of inner hair cells bend?
Actin stretches and opens a trap door, allowing K+ ions into the hair cell which initiates neural signaling by releasing glutamate
47
What is tonotopic organization?
Neurons activated by similar frequencies are found close to each other
48
What percent of neurons respond to noise, clicks, and bangs?
40%
49
What percent of neurons respond to a certain frequency?
60%
50
What is place code?
The activity of specific neurons encodes different frequencies
51
What is resonance theory?
Basilar membrane appeared to be composed of transverse fibers Sounds make fibre vibrate like a harp-string Each fibre activated by a certain frequency
52
What is the problem with resonance theory?
The basilar membrane is all connected, no independent stringlike fibres
53
What is the traveling wave?
The entire membrane vibrates The basilar membrane differs in elasticity down its length -narrow/stiff at base -wide/floppy at helicotrema Each frequency has its own point of maximum displacement along the membrane -high frequencies at the base -low frequencies at the apex
54
What is the evidence for traveling wave theory?
Observation Many auditory neurons display frequency tuning curve, responsive to a narrow range of frequencies Tonotopic organization Stimulation deafness experiments Motile response Masking experiments
55
What is the point of greatest sensitivity?
Characteristic frequency
56
What is cochlear amplification?
Outer hair cells sharpen wave around the peak by tilting and changing length
57
What is tonotopic organization?
Nerve fibres coming from the base are tuned to high frequencies Those from the apex are tuned to low frequencies
58
What are stimulation deafness experiments?
High intensity sounds damage parts of the organ of Corti Damage depends on what frequency was played
59
What is motile response?
Pattern of vibration on the basilar membrane is narrower than what Bekesy found Active process sharpens waves
60
What is two-tone suppression?
Present tone at characteristic frequency of a neuron Turn on another tone, close in frequency to the other Neuron's response rate decreases Due to outer hair cells affecting movement of basilar membrane
61
What are masking experiments?
One sound prevents us from hearing another Masking increases as masker and target frequencies become closer Making is asymmetrical = target frequencies higher than masker are more affected than frequencies lower than masker
62
What is perceptual coding?
When we reduce audio file size by removing frequencies that would've been masked anyways
63
What is periodicity pitch?
The case of the missing fundamental
64
How is periodicity pitch a problem for place coding?
Region on basilar membrane is not moving, so how is pitch corresponding to that location heard?
65
What is temporal code?
The timing of neural activity encodes different frequencies
66
What is frequency theory?
Entire basilar membrane vibrates in synch with frequency Assumed that each vibration produced one action potential in all receptors
67
What are the problems with frequency theory?
Only part of the membrane moves There is a refractory period for hair cells
68
What is the volley principle?
Groups of neurons fire alternately in volleys, some fire while others are refractory
69
What is phase locking?
Neuron firing is synchronized with the peak of a pure tone stimulus Does not work well with high frequencies, better with low frequencies
70
What is tinnitus?
Ringing in the ears, or experiencing a sound when none is present
71
What is tinnitus commonly caused by?
Loud sounds, drugs, ear infections, food allergies
72
What are the current theories of tinnitus?
Destroying hair cells causes the brain to remap areas previously served by the destroyed hair cells, resulting in abnormal brain activity Due to decreased incoming stimulation, there is less inhibition in the auditory cortex, resulting in ore excitatory activity and phantom sound
73
What is presbycusis?
Age-related hearing loss, due to the degeneration of hair cells and cilia More likely to occur with increasing age Higher frequencies are more attenuated with age