Hearing Flashcards
what is pitch
changes in frequency of air over time
what is pitch humans perceive
20Hz-20KHz
what is loudness in sound
diff between compressed and rarefied air
how is loudness measured
in Db - logarhythmic so need 10 fold increase to double
what is in the middle ear
air filled space with tympanic cavity and ossicles
what do the ossicles span
from tympanic membrane to the oval window of the inner ear
what are muscle of ossicle and what innervates them
tensor tympani - V3
stepedius - 7
what is point of muscles and what happens if gone
dampen loud sounds - otherwise hyperacusis
what is in inner ear
fluid filled space with the vestibule and cochlea
what does cochlea spiral around
modiolus
what are 3 spaces of cochlea and what are they filled with
scala vestibuli - peripymph
scala vascularis - endolymph
scala tympani - perilymph
where is endo lymph from?
stria vascularis - high in K
what does the organ of corti rest upon and how does is change along the cochlea
bony spiral lamina - turns to basilar membrane - basilar membrane widens from base to apex
how does cochlea change from base to apex
narrows
where does sound start and end
begins from foot of stapes in oval window and out the round window on other side
what does organ of corti do
turns sound E into receptor potential
what is a place code
specific point on the basilar membrane where a specific frequency causes maximal displacement
what is covering of organ of corti
tectorial membrane
what are 2 types of hair cells and where are they located
outer hair cells - through endolymph into membrane
inner hair cells - into endolymph, but not membrane
how are hair cells orders
by hieght, with shortest closest to modiolus
what happens with basilar membrane moves up or down
up - hairs cells move inwardsm so stereocilia move out
down - hair cells move out, so hairs move in
what does bending cause
receptor potential
what happens in bending of 2 directions
towards tallest - depol
towards shortest - hyperpol
how does depol happen
movement causes opening of K channels> K in> depol> Ca enters> neurotransmitter released
what is ratio of OHC to IHCs
3:1
where is most ganglionic input from
95% from IHC
what do OHCs do?
amplify mvmt of the basilar membrane to increase low intensity sounds
what is path of auditory conduction
coch nerve>ipsi coch nuclei>bilateral projection to inf. coll.> medial geniculate nucleus of thalamus
how can unilateral deafness occur (3)
damage to the
- ear
- cochlear nerve
- cochlear nuc.
