week 8 (auditory) Flashcards
(38 cards)
1
Q
define: sound in psychology and physics terms
A
PSYCH
- physical event that must be converted into biological signal to produce perceptual exp. of hearing
PHYS
- vibrational disturbance of a medium
2
Q
define: inertia and elasticity
A
- inertia = moving things want to keep moving + static things want to be static
- elasticity = things want to return to OG state
3
Q
explain: mvt of particles when tuning fork is struck
A
- neighboring air molecules are compressed
- fork moves in opp. direction -> causes molecules to relax (rarefaction)
- pattern of compression and rarefaction -> wave
4
Q
define: pure tone
A
- single sinusoidal function
- simplest sound wave
5
Q
explain: basic qualities of sound waves (2)
A
-
amplitude
- psi change from peak to peak
- lowest to highest
- perceptual quality = loudness -
frequency
- number of cycles that occur per second
- perceptual quality = pitch
**wavelength = distance between peaks
6
Q
question: relationship between wavelength and frequency?
A
- shorter wavelength = higher frequency -> higher pitch
7
Q
question: what’s the audible frequency range for a healthy human?
A
20 - 20000 Hz
8
Q
define: periodic sound
A
- pattern of psi change repeats itself over regular intervals over time
9
Q
define: fundamental freq.
A
- lowest freq. component of the sound
- part of harmonic series
- all other harmonics = integer multiples of the fundamental
10
Q
define: white noise
A
- noise containing all the freq. w/in a particular range
- random vibrations (no apttern)
11
Q
explain: fourier spectrums
A
- displays how much energy or amplitude i present at multiple frequencies
- y axis = intensity
- x axis = frequency
- 1 line = pure tone
⤷ more than one line = complex tone
12
Q
question: how does sound intensity change with distance?
A
- diminishes with distance
- moving wave is like a sphere
- increasing the SA of the sphere = energy spreading over a larger surface = intensity decreases
13
Q
name: ways sound can interact with objects (3)
A
-
reflected
- sound bounces back after hitting a boundary -
absorbed
- E transferred from one medium to another -
diffracted
- wanes bend around an object, reforms, and continues
⤷ easier for lower freq. bc longer wavelengths = easier to bend
14
Q
name: important structures of the outer ear + functions (3)
A
-
pinna
- funnels sound
- helps increase range of audible sound -
external auditory canal
- channels sound to eardrum
- protects eardrum -
tympanic membrane
- eardrum
- elastic mem. that seals of canal
- sound waves cause it to vibrate
15
Q
name: important structures of the middle ear + functions (2)
A
-
ossicles
- malleus = hammer
⤷ attached to eardrum + connects to incus
- incus = anvil
- stapes = stirrup
⤷ connects to oval window
- suspended in air + connected by ligaments
- helps with transmitting vibrations more efficiently
-
eustachian tube
- equalizes psi across eardrum
⤷ allows the mem. to vibrate properly
16
Q
name: important structures of inner ear + functions (2)
A
-
semicircular canals
- part of vestibular
- helps with balance -
cochlea
- 3 parallel canals separated by 2 mem.
⤷ basilar mem. and reissner’s mem.
- base of cochlea = beginning
- apex of cochlea = tip
17
Q
name: order of sound transmission through ear
A
pinna
external auditory canal
tympanic mem.
malleus
incus
stapes
oval window
vestibular canal/scala vestibuli
basilar mem.
tympanic canal/scala timpani
round window
**vestibular and tympanic canals are connected
18
Q
explain: process of sound transmission (starting from middle and inner ear)
A
- inward displacement of stapes on oval window (pushes in)
- psi gradient sent across reissner’s mem. into middle canal
- basilar mem. moves
⤷ causes hair cells to move
⤷ affects transduction apparatus (of hair cells) - increased psi in tympanic canal is relieved by outward mvt of round window
19
Q
define: organ of corti and hair cells
A
- organ of corti = gelatinous layer floating above inner hair cells and attached to outer hair cells
- inner = afferent into to brain, outer = efferent info from brain
20
Q
explain: how basilar mem. and hair cells contributes to auditory transduction
A
- basilar mem. moves with wave
- tectorial mem. and hair cells move in opposite directions
⤷ shearing - moving hair cells stretches the tip links
- opens K+ channels
- depol. hair cell
- Ca+ opens
- NT released -> AP in cocholar nerve -> sendings info to auditory centers
21
Q
question: how do ossicles dampen sounds?
A
- muscles in middle ear reduce mvt of ossicles
- helps prevent possible damage to inner ear by tensing the musc. in ear
works well for prolonged exposure
⤷ not the best for sudden sounds bc not fast enough to react
22
Q
question: how does amplitude impact hair cells?
A
- larger amp = louder sound
- tympanic mem. and oval window moves more
- bulge in vestibular canal = larger -> more deflection from basilar and tectorial membranes
- greater force on hair cells
- greater depol. and more NT release
23
Q
question: how is freq. encoded in the cochlea?
A
- base = skinnier + more tension = higher freq.
- apex = wider + less tension = lower freq.
- diff. in width and tension of basilar mem. prod. diff. frequencies
- basilar mem. has tonotopic mapping for freq.
24
Q
question: where are the cells bodies for auditory nerve fibers? what nerve transmits auditory info?
A
- bipolar neurons
- bodies in cochlear ganglion
⤷ right outside cochlea - terminate on inner and outer hair cells
⤷ mostly inner - info transmitted by vestibulocochlear nerve
⤷ through cochlear branch
25
define: characteristic freq.
- lowest point on tuning curve
- freq. where afferent fiber is most sensitive
26
explain: tuning curve (axes?)
- plots thresholds of neuron in resp. to sine waves w/ varying freq. at the lowest intensity that has a resp
- x = freq.
- y = threshold intensity req. to stim. a fiber above spont. firing rate
27
question: how do outer hair cells work (which way do they carry info?)
- efferent
⤷ carry info from brain
- causes hair cells to be physically longer to reach further into tectorial mem.
- has contractile element
28
explain: phase locked resp. and temporal code
- firing at the same rate as incoming sound wave
29
define: volley principle
- multiple neurons encode higher freq. as a group
⤷ work together
- phase locking but dispersed over several neurons
30
question: what happens to auditory nerve fibers at higher intensities?
- less selective
⤷ bc rate saturation
- after a certain point, firing rate can be activated by many diff. tones
**vv very selective at low intensities
31
name + explain: types of afferent auditory neurons (2)
1. **high spontaneous fibers**
- high AP freq.
- lower activation threshold
- saturates at low stim.
⤷ won't increase firing rate even if increase intensity
2. **low spontaneous fibers**
- low AP freq.
- higher activation threshold
- saturates and higher intensities
32
name: steps neural pathways in auditory system
cell bodies in **cochlear ganglion/spiral ganglion**
**cochlear nucleus** (rostral medulla)
⤷ can split off to be contralateral or ipsilateral
⤷ neurons here are monoaural (from one ear)
**superior olive** (pons)
⤷ first major site for sound localization
⤷ neurons are binaural (so it helps w/ localization)
**inferior colliculus** (caudal midbrain)
⤷ coordinates auditory reflexes
**medial genicular nucleus** (thalamus)
⤷ relay station to primary cortex
**primary auditory cortex** (temporal lobe)
**each cochlear nucleus sends to 4 places (sup olive and inferior colliculus for ipsilateral and contralateral)
33
question: from what structure in the auditory pathway do the neurons start being binaural?
- most neurons above cochlear nucleus
34
question: is contralateral and ipsilateral usually excitatory or inhibitory?
- contralateral = opp. side
⤷ usually excitatory
- ipsilateral = same side
⤷ can be both
35
question: where and what is the secondary auditory cortex?
- immediately surrounds A1 and receives input
- less sensitive to simple sounds (good for complex tones)
36
name: ways hearing loss is categorized (2)
1. described by site of damage
- obstructed canal = sound waves can't exert psi on eardrum
- conductive loss = ossicles lose ability to conduct vibrations -> less sound going to cochlea
- sensorineural loss = damage to cochlear or other nerves in inner ear
2. described by age of onset
- congenital loss = generic cause assoc. w/ birth
- acquired = later in life
37
explain: middle ear infections
- otitis media
- inflammation of eustachian tube
- psi builds up -> prevents vibrations
- fluid build up can interfere with ossicles
- more common in children bc tube is smaller and more horizontal
38
explain: osteoclerosis
- type of conducive hearing loss
- inherited bone disease that prod. abnormal dev. and function of ossicles
- increases accumulation of calcium
- reduces amplification of sound
