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91 terms

Exam 2 - wave senses

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outer ear consists of
pinna and auditory canal
functions of outer ear
funnels sound, causes eardrum to vibrate
middle ear consists of
tiny bones (ossicles) linking eardrum to oval window
function of middle ear
increase pressure exerted in inner ear
inner ear consists of
cochlea; fluid filled structure
function of inner ear
where transduction takes place
what type of sense is hearing
wave
amplitude determines
loudness
frequency determines
pitch
hair cells
in cochlea, receptor cells for hearing located along basilar membrane
basilar membrane
membrane on the floor of the inner duct of the cochlea
how hearing works
vibration of ossicles against oval window causes waves in basilar membrane, hair cells bend causing impulse and neurotransmitters released by hair cells act upon auditory neurons
basilar membrane characteristic
flexible
tectorial membrane
runs parallel to basilar membrane inside inner duct
eardrum
separates outer ear from inner ear
oval window
membrane at the far end of middle ear, smaller area than tympanic membrane so pressure funneled
where are hair cells located
on the basilar membrane
cilia
tiny hairs that protrude from each hair cell into inner duct and abut against tectorial membrane
tectorial membrane characteristics
less flexible (doesn't move when basilar membrane moves)
conduction deafness
deafness that occurs when ossicles in the middle ear become rigid and cannot carry sounds inward from tympanic membrane to cochlea
what can people with conduction deafness hear?
vibrations that reach cochlea by routes other than middle ear
conventional hearing aid is
a device that magnifies sound pressure sufficiently for vibrations to be conducted by other bones on the face into the cochlea
what helps people with conduction deafness
a conventional hearing aid
sensorineural deafness
deafness resulting from damage to hair cells of cochlea or auditory neurons
cochlear implant is
a device that performs the transduction task normally done by the ear's hair cells by translating sounds into electrical impulses and sending impulses through wires permanently implanted into cochlea where they stimulate terminals of auditory neurons
when can cochlear implant be used
when deafness results from destruction of hair cells, not when auditory nerve has been destroyed
types of deafness
conduction deafness and sensorineural deafness
position in membrane at which wave reaches peak amplitude depends on
frequency of the tone
distance traveled by high frequency waves is
short
distance traveled by low frequency waves is
long
bekesy's hypothesis about hearing
rapid rifing in neurons that come from proximal end of membrane accompanied by little or no firing in neurons from more distal parts is interpreted as high pitched sounds; rapid firing neurons from more distal portion of membrane interpreted as lower pitched sounds
auditory masking
the ability of one sound to mask (prevent hearing of) another sound
asymmetry of auditory masking
low frequency sounds mask high frequency sounds much more easily than high frequency sounds mask low frequency sounds
pattern of hearing loss with age
sensitivity to high frequency lost to a much greater degree than low frequencys with age
why does hearing change with age?
because of wearing out of hair cells with repeated use (coding for high frequencys acted upon by all sounds, low frequency hairs only acted on by low frequency sounds)
for relatively low frequencies, percieved pitch depends on
which part of basilar membrane is maximallhy active and the timing of that activity (ie frequency of action potentials)
auditory sensory neurons send their output where
to nuclei in the brainstem which sends axons to primary auditory area of cerebral cortex
how are neurons in primary auditory cortex organized
tonotopically
tonotopically definition
high-frequency tones activate neurons on one end of cortex, low-frequency tones activate neurons on other end
what determines the general form of hte tonotopic map
heredity
what determines the specific amount of cortex that is devoted to any particular range of frequencies
experience
intraparietal sulcus
area of the parietal lobe of the cortex which receives input from the primary auditory cortex; involved with music perception and visual space perception
sound localization depends on
the time at which each sound wave reaches one ear compared to the other
how are words identified?
from patterns in change of frequency and amplitude that occur over time as the word is spoken
phonemes
individual vowel and consonant sounds that make up words
phonemic restoration
an illusion in which people hear phonemes that have been deleted from words or sentences as if they were still there
what determines which sound is heard in phonemic restoration
the surrounding phonemes and meaningful words and phrases that they produce
how do auditory neurons vary
some have higher thresholds than others; brain uses info about pattern of impulses to perceive loudness; different auditory neurons respond to different differences in time sound received
rods
very sensitive to light, not sensitive to color
cones
not as sensitive to light, involved in color vision
where are rods concentrated
on the periphery of the retina
where are cones concentrated
at the fovea
what are there more of, rods or cones?
more rods (120-125 million) than cones
photoreceptors
specialized light-detecting cells that evolved and became connected to animal's nervous system
retina
membrane lining rear interior of the eyeball; where photoreceptors located
cornea
convex transparent tissue that covers the front of the eyeball
function of cornea
helps focus light that passes through cornea
iris
immediately behind cornea; pigmented doughnut-shaped, provides color of eye
pupil
black-appearing center in the iris; hole through which light can pass into the eyeball
lens
behind the iris, adjustable
function of lens
adds to focusing process begun by cornea
how does lens shape change
becomes more spherical when focusing on objects close to eye, flatter when focusing on those farther away
transduction
process by which a stimulus from the environment generates electrical changes in neurons, done by photoreceptor cells
fovea
pinhead-size area of hte retina that is in teh most direct line of sight, specialized for high visual acuity
acuity
ability to distinguish tiny details
photochemical
a chemical that reacts to light; present on outer segment of each photoreceptor
rhodopsin
the rods' photoreceptor
how many types of cones are there
3
optic nerve
neurons that run from the back of the eye to the brain
blind spot
the place on the retina where the axons of neurons converge to form optic nerve
cone vision
aka bright light vision or photopic vision; specialized for high acuity and color perception
rod vision
aka dim-light vision or scotopic vision; specialized for sensitivity (ability to see in dim light)
dark adaptation
the graduali ncrease in sensitivity that occurs after you enter a darkened room
light adaptation
the more rapid decrease in sensitivity that occurs after you turn on a bright lamp or step out into sunlight
how does bright light make rods nonfunctional
light causes rhodopsin to break down into two inactive substances
bipolar cells
short neurons on which rods and cones form synapses
ganglion cells
longer neurons whose axons leave the eye at the bind spot to form the optic nerve
where do bipolar cells form synapses
on ganglion cells
how does convergence vary between rods and cones
rods have lots of convergence, cones have little or no convergence
place theory
pitch perceived determined by where in cochlea waves reach peak amplitude
pigments
chemicals that absorb some wavelengths and thereby prevent them from being refelcted
subtractive color mizing
the mixing of pigments; pigments create color by subtracting (absorbing) some of the light waves that would otherwise be reflected to the eye
white
no wavelengths of light absorbed, all reflected
black
all wavelengths absorbed, none reflected
additive color mixing
occurs when colored lights are mixed
three primaries law
different wavelengths of light can be used to match any color that the eye can see if they are mixed in the appropriate proportions
primaries
any three wavelengths as long as one is from the long-wave end of spectrum, one from short-wave end, and one from middle
law of complementarity
pairs of wavelengths can be found that, when added together, produce the visual sensation of white
saturated colors
colors produced by a single wavelength
unsaturated
colors that come more and more to resemble white
standard chromaticity diagram
can be used to determine color that will result from mixing three standard primaries and which pairs of wavelengths are complimentary