audition - jullet Flashcards
(100 cards)
1
Q
Pressure waves are generated by:
A
vibrating air molecules
2
Q
Amplitude corresponds to:
A
loudness
3
Q
Frequency corresponds to:
A
pitch
4
Q
complexity corresponds to:
A
timbre (also called tone color)
5
Q
What does timbre mean?
A
CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)CHARACTERISTICS and QUALITIES of sound which allow the ear to distinguish sounds that have the same pitch and loudness. Examples: warm, full, thin, cold)
6
Q
How do sound waves expand?
A
sound waves expand in a spherical shell in 3D
7
Q
Humans are unable to detect these frequences:
A
infrasound (20kHz)
8
Q
What is the human auditory frequency spectrum? What is the peak sensitivity?
A
Range: 20-20kHz. Peak sensitivity: 2-3kHz
9
Q
What frequency of speech?
A
2-3kHz
10
Q
How does the external ear help in auditory transduction? (2)
A
The auricle helps to collect sound. The external acoustic meatus boosts sounds 30-100x at 3kHz
11
Q
How does the middle ear help in auditory transduction? (2)
A
The middle ear boosts sound pressures 200x via 1) energy transfer from a larger tympanic membrane to a smaller oval window, 2) mechanical action of the 3 ossicles, but also responds to loud sounds through the 3) attenuation reflex
12
Q
What is the attenutation reflex?
A
tensor tympani and stapedius muscle stiffens the ossicles in response to loud sounds and this reduces the amount of sound pressure transmitted ot the cochlea.
13
Q
What two small muscles of the middle ear are involved in the attenutation reflex?
A
tensor tympani and stapedius muscle.
14
Q
What is Bells palsy?
A
damage to tensor tympani and stapedius muscles causes them to remain flaccid, which results in hyperacusis (extra sensitivity to moderate or even low intensity sounds)
15
Q
Why is amplification of sound waves important?
A
when sound waves travel from air to fluid, this results in a loss of pressure. Amplification is necessary to boost that pressure so that when it gets transmitted to vibrations, not much is lost.
16
Q
What is the tensor tympani innervated by?
A
trigeminal nerve.
17
Q
What is the stapedius innervated by?
A
facial nerve.
18
Q
What normally helps to equalize pressure of he middle ear to atmospheric pressure?
A
eustachian tube
19
Q
What produces endolymph?
A
stria vascularis
20
Q
What part of the cochlea contains endolymph? Perilymph?
A
Endolymph: scale media. Perilymph: scala vestibuli/scala tympani
21
Q
How is the basilar membrane different at the apex vs the base? How does it affect the vibrations?
A
The APEX is wider and more flexible, which results in more vibrations during LOWER frequencies. The BASE is narrower and stiffer, which results in more vibrations during HIGHER frequencies.
22
Q
What is tonotopy of the basilar membrane?
A
systematic representation of sound frequency along the cochlea
23
Q
Where are the scala vestibuli and tympani connected?
A
at the far end of the cochlea - the helicotrema
24
Q
How is the perilymph different from the endolymph in terms of K?
A
Endolymph contains HIGH K concentrations and perilymph contains LOW K concentrations, which translates to a 80mV difference between the two fluids
25
What does the organ of corti consist of?
hair cells, support cells, and tectorial membrane
26
What are hair cells?
Hair cells are the sensory receptors of the auditory system and are located within the organ of cortion a thin basilar membrane in the cochlea.
27
The tectorial membrane overlies the outer hair cells and inner hair cells, which are connected to axons. What type of axons are connected to each?
Afferent axons forms synapses on the base of the inner hair cells and transmit information about the sound frequency to the cochlear nuclei in the CNS (via spiral ganglion), while efferent axons from the superior olivary complex travel to the outer hair cells
28
What is the purpose of having efferent fibers from the superior olivary complex to the outer hair cells?
Activation of the efferent fibers to the outer hair cells serves to DAMPEN the response to LOUD sounds, such that there is less response in the afferent fibers from the inner hair cells to the cochlear nuclei in the CNS (via spiral ganglion)
29
What's the difference between stereocilia and kinocilia?
Stereocilia are bundles of hair extending from the apical end of the hair cell and push up against the tectorial membrane. Kinocilia is the tallest stereocilium and the only true cilia
30
What are tip links?
proteins that connect the tips of stereocilia in adjacent rows in the bundles.
31
What causes the K+ channels on hair cells to open? What causes them to close?
Movement of the stereocilia AWAY from the kinocilium causes the K channels to CLOSE (hyperpolarization). Movement of the stereocilia TOWARD the kinocilium causes the K channels to OPEN (depolarization). Think: AC-TO
32
What causes the stereocilia/kinocilium to bend/deflect?
vibration of the basilar membrane
33
What's the difference between the basilar membrane and the tectorial membrane?
Basilar membrane - separates the scala media and the scala tympani and is where the inner hair cells and outer hair cells are attached. Tectorial membrane - a gel-like struture situated above the organ of corti and is where the stereocilia of the hair cells attach to
34
Why are K channels on hair cells considered to be mechano-sensitive channels.
If the cilia bends toward the longer cilia, the tip links pull open the K channels, allowing K to flow in (depolarization). If the cilia is bends away from the longer cilia, the tip links closes the K channels (hyperpolarization)
35
Outer hair cells display electromotility. What does this mean? What purpose does it serve?
DEPOLARIZATION: outer hair cells shorten to increase inner hair cell displacement (allows for MORE basilar membrane movement). HYPERPOLARIZATION: outer hair cells lengthen (allows for LESS basilar membrane movement). Purpose: protection mechansim used to dampen the vibrations of the basilar membrane if the sounds are too loud.
36
What happens to K when the K channels in the stereocilia open?
Because the endolymph has a very high conc. of K+, when the K+ channels open, K+ ions flow INTO the cell.
37
What is the driving force for K entry into the hair cell during depolarization?
1) the interior of the cell is negative (-45mV) due to the low K+ concentration, and the total membrane potential is equivalent to +80 mV (due to the high K+ in the endolymph). Thus there is a total of 125 mV of driving force for K+ entry into the cell.
38
What are the two mechanisms the middle ear employs to dampen loud sounds?
1) attenutation reflex with the tensor tympani and stapedius muscles to reduce the amount of energy the ossicles transmit to the oval window. 2) changes in the length of the outer hair cells to dampen the vibrations to the basilar membrane.
39
What is prestin?
motor protein on the membrane to help change the length of the cell and it helps to minimize vibrations on the basilar membrane
40
How do changes in the length of outer hair cells protect the cochlea from damage?
change in the length of the outer hair cells that affects the extent of the basilar membrane movement: longer hair cells stiffen the basilar membrane -> dampens vibrations in response to loud sounds and protects the cochlea from damage.
41
What is the cochlear amplifier?
change in the range of basilar membrane movement (as a function of the outer hair cell length) to either 1) dampen background noise, or 2) selectively enhance specific frequencies
42
Afferent nerves from the cochlea form:
spiral ganglion
43
What is tonotopic organization of auditory nerve fibers mean? How is the basilar membrane tonotopically organized?
Inner hair fibers have "best" frequency at which they have the greatest sensitivity (lowest threshold) and there is a tonotopic organization and projection of these fibers to the cochlear nuclei in the brainstem. Apex: low frequency. Base: high frequency.
44
How is the basilar membrane tonotopically organized?
Apex: low frequency. Base: high frequency.
45
Projections to the DORSAL COCHLEAR NUCLEI conveys this type of auditory information.
frequency (high/low pitch)
46
Projections to the VENTRAL COCHLEAR NUCLEI conveys this type of auditory information.
sound localization (as a function of intensity/time delay arriving at each ear)
47
Projections to the MEDIAL SUPERIOR OLIVE from the ventral cochlear nuclei conveys this type of auditory information.
time delay in the ears (used to localize sound)
48
The medial superior olive has dendrites that recive info from both ears. When are the cells maximally stimulated?
when information from both ears reaches the neuron at the SAME time.
49
How do neurons in the medial superior olive compare the time delay of sound arriving in the two ears? Use the example of placing a loud speaker on the L ear.
Remember, cells of the medial superior olive is maximally stimulated when information from BOTH ears reaches a particular neuron at the SAME time. Because the L ear is closer to the loudspeaker), information from the L cochlea has to travel a longer axon distance to stimulate the SAME neuron that is also stimulated by R ear (which has to travel less of a distance to reach the same neuron) - see page 40 for diagram
50
Projections to the LATERAL SUPERIOR OLIVE from the ventral cochlear nuclei conveys this type of auditory information.
intensity difference in each ear (used to localize sound)
51
How does the lateral superior olive neurons detect intensity differences in the two ears (as a way to localize sound)?
lateral superior olive neurons are stimulated by sound in the same ipsilateral ear, and this sends an excitoroy inhibited by sound coming in from the contralateral ear via inhibitory neurons in the medial nucleus of the trapezoid body (MNTB)
52
What is the importance of the medial nucleus of the trapezoid body (MNTB)?
Information that comes in to one ear sends excitatory signals to the MNTB, which stimulates an inhibitory neuron that inhibits input coming in from the other ear.
53
Projections to the INFERIOR COLLICULUS conveys this type of auditory information.
auditory map
54
What is the projection of the auditory information?
Nerve fibers in the cochlea come from neuron cell bodies in the spiral ganglion. Projections from these spiral ganglion neurons in turn form the eighth nerve and project to the dorsal and ventral cochlear nuclei, then to superior olivary nuclei, to inferior colliculus, to the medial geniculate of the thalamus, and finally to temporal lobe (superior temporal gyrus) of the cortex (insula).
55
Where do projections from the superior olive and lateral leminiscus end up?
in the inferior colliculus, where an auditory map is made
56
Where does the inferior colliculus project to?
medial geniculate nucleus of the thalamus, where it selects for a combintion of frequencies and specific time differences between the two frequencies.
57
Where does the medial geniculate nucleus of the thalamus project to?
primary auditory cortex in the superior temporal lobe (and heschl's gyrus)
58
The inferior colliculus is equivalent to this structure in birds.
optic tectum
59
Where is the primary auditory cortex?
superior temporal lobe (and heschl's gyrus)
60
How is the primary auditory cortex organized?
it has a tonotopic projection from the cochlea, where the anterior-most part corresponds to the apex of the cochlea and the posterior-most part corresponds to the base of the cochlea. Cells with the same optimal frequency are arranged in vertical columns with an anterior->posterior organization
61
Where is the secondary auditory area (belt areas)?
It is on the superior temporal lobe, but just inferior to the primary auditory cortex.
62
What is the secondary auditory area (belt areas) used for?
it contains neurons that are sensitive to specific combination of sounds used in vocalizations
63
What is Wernicke's area?
area posterior to the primary auditory cortex and is considered as an auditory association area (understanding speech). Receives input from visual and auditory areas of the cortex.
64
Auditory information is processed in different areas of the brain. What areas are involved in determining the PITCH of the sound?
the ventral stream, which consists of the primary auditory cortex and inferior frontal gyrus. PVPI
65
Auditory information is processed in different areas of the brain. What areas are involved in determining the LOCATION of the sound?
the dorsal stream, which consists of the superior parietal cortex and the superior frontal gyrus.
66
Neurons in the auditory cortex have very specific sensitivities to:
1) specific combination of frequencies, 2) specific durations, 3) specific patterns, 4) combination of sounds (syllables, phonemes, etc)
67
What are phonemes?
commonly used sounds that correspon to what we consider as letters: "b" "e"
68
What are lexemes?
combination of phonemes that correspond to sound groups: "th" "st" or short words like "we"
69
What two factors do bats use to determine where objects are?
Constant frequency (CF) and frequency modulated (FM) components. During echolocation, when the echo comes back, there is 1) a doppler shift in the CF component, which tells the bat what the distance to the object is and 2) a time delay in the FM component, which tells the bat how fast the object is moving.
70
What does the doppler shift in the constant frequency component tell a bat?
how far the object is
71
What does the time delay in the frequency modulated component tell a bat?
how fast the object is moving
72
How is human speech related to the bats use of echolocation to detect objects?
Human speech often has constant frequencies and frequency modulated sweets during different syllabules, and is therefore a series of time-varying signals, frequency combinations, with different phoentic sequences detected as syllables
73
What brain area is involved in synthesizing/motor control of speech?
Broca's area. Think if you have a stroke in this area, you will have "broken" speech (but will still be able to comprehend speech because the Wernicke's area is still intact)
74
What is Broca's aphasia?
ability to comprehend speech, but not prorduce it
75
What brain area is involved in speech comprehension?
Wernick's area. Think if you have a stroke in this area, you will not be able to understand speech and thus words will be jumbled up into a "word salad"
76
What is Wernicke's aphasia?
It is a lesion in Wernicke's area that causes one to not be able to understand speech
77
Wernicke's area receives information from:
auditory cortex and visual cortex.
78
What is the arcuate fasciculus?
white matter tract that connects Wernicke's area to Broca's area.
79
What connects Wernicke's area to Broca's area?
arcuate fasciculus?
80
What happens if there is a lesion in arcuate fasciculus?
aphasia similar to Broca's aphasia
81
What is the supramarginal gyrus? What is it important for?
It is located in the parietal lobe and is important for matching sounds to meaningful phonemes
82
What is the angular gyrus? What is it important for?
It is located in the parietal lobe, just posterior to the supramarginal gyrus, and is important for matching graphemes (visual language information - written syllables/words) to meaningful phonemes
83
Speech comprehension typically involves these two cues: (bonus points if you include the cortex as well)
Visual cues: supramarginal gyrus. Audio cues: angular gyrus
84
What is the McGurk Effect?
When presented with one sound, but given the visual image of a face producing another closely related but distinct sound, the viewer will percieve a third, unrelated sound. (ie if hear "pa", see "ka", will report hearing "ta")
85
What part of the cortex plays a role in reporting PITCH changes? What about abnormal changes in temporal patterns of music?
both of these involves the right regions of the temporal lobe and hippocampus.
86
What happens to the brain upon musical training?
there are increases in the MOTOR areas involved in producing music, but also AUDITORY areas involved in processing music (heschl's gyrus)
87
What is conduction deafness?
loss of conduction of sound from outer ear to cochlea (ear wax, rupture of tympanic membrane, pathology of the ossicles)
88
What is sensorineural deafness?
loss of hair cells or of neurons in the auditory nerve.
89
What is acquired hearing loss?
main causes include ear trauma, infection, old age, ototoxic drugs
90
What is genetic hearing loss?
mutations in genes (channels/transporters) involved in maintaining high K concentrations in the endolymph.
91
What is presbycusis? What causes it?
age-dependent loss of high-frequency hearing; probably due to a loss in the flexiblity of the basilar membrane
92
What is hyperacusis? What is the possible root of the problem?
extra sensitivity to moderate or low intensity sounds; can result from damage to the tensor tympani and stapedius muscles in the middle ear (or their innervation), so they remain flaccid.
93
What is the Rinne Test?
used to distinguish between conduction vs sensorineural deafness.
94
What is auditory agnosia?
inability to identify the meaning of a non-verbal sound - can hear it but do not know what it means (ie - hear a doorbell, but don't know that it is associated with the door)
95
What is congenital amusia? What areas of the cortex is affected?
hereditary tone deafness - people are unable to detect pitch changes in melodies (ie inability to detect out-of-tune singing). Associated with abnormalities in the auditory cortex and inferior frontal cortex.
96
What is tinnitus? What is the possible root of the problem?
perception of sounds in the absence of a stimulus (ringing, buzzing, humming). Could accompany diseases involving cochlea, auditory nerve, or even changes in the auditory cortex.
97
What is the possible molecular cause of tinnitus?
Peripheral synapses (between the hair cells and the afferent axons) uses NMDA/glutamate receptors and there is some evidence that changes in this receptor results in constant stimulation of nerve endings, resulting in the perception of sound in the absence of stimuli.
98
What is an acoustic neuroma?
It is a slow-growing, benign tumor of SCHWANN CELLS that originates on the vestibular nerve. As they grow, they influence the cochlear nerve as well, so the initial symptoms are more cochlear.
99
What is Meniere's Disease?
progressive hearing loss due to excess fluid build-up in the endolymphatic sac - cause is unknown, but could be due to a blockade or restriction of the endolymphatic duct or in the over-production of endolymph by the stria vascularis.
100
How do cochlea implants work?
a microphone on the side of the head sends signals to a processor, which converts the frequency of information into a digital signal. This information is sent to a receiver under the scalp, which sends signals through wires threaded into the cochlea, and the wires can selectively stimulate auditory nerve at various places along the cochlea.
