Lecture 13 - Structure and function of the auditory system Flashcards
which type of waves are sound waves?
longitudinal
what is the relation of frequency to length of sound wave?
inversely related
what does fundamental frequency (f0) correspond to in sound?
the repitition rate/pitch of the sound
harmonics are integer multiples of what?
fundamental frequency
what is sound intensity measured in?
decibels
in a spectogram what do lighter areas represent?
more energy/power
is sound intensity a log scale?
yes
what are the main 2 components of the outer ear and what is their main function?
pinna and ear canal, collect and focus sound waves
what are the main 2 components of the middle ear and what is their main function?
tympanic membrane and ossicles, transmit vibrations to the cochlea
what is the main component of the inner ear and what is its main 2 functions regarding its 2 types of hair cells?
cochlea
outer hair cells amplify vibrations and inner hair cells tranduce mechanical vibrations to electrical nerve signals
name the 3 ossicles of the middle ear
malleus, incus, stapes
what connects the cochlea to the foot of stapes?
oval window of cochlea
travelling waves on the basilar membrane displace the……… as the basilar membrane is …..
organ of corti, fluid
where are high frequency waves decoded on the basilar membrane? where are low frequency waves decoded?
high = base
low = apex
in which section of the ear is the ear drum located?
middle ear
which type of cochlear hair cells actively move which in turn amplifies membrane vibrations? what does this do to the sensitivity of the other type of cochlear hair cells?
outer hair cells, enhances sensitivity of inner hair cells
which type of cochlear hair cells Get sound into the brain and are Displaced passively by vibrations?
inner hair cells
otoacoustic emissions (OAEs) measure the activity of which type of cochlear hair cells doing what?
outer hair cells causing physical vibrations, propagating thwm back to the tympanic membrane and into the air
name the 2 types of otoacoustic emissions
spontaneous (s) and sound evoked (te and dp)
what is a useful clinical test of cochlear health in some situations?
otoacoustic emissions using sensitive microphones
what is the range of frequency detection for humans?
20 - 20,000 Hz
does an input from 1 cochlea reach one or both sides of the brain?
both
name the 5 stages of the ascending auditory pathway
cochlear nuclei (dCN, vCN)
superior olivary complex
inferior colliculus
medial geniculate body
auditory cortex
where in the brain is the medial genicuate body found (ascending auditory pathway)?
thalamus
which structure in the ascending auditory pathway receives early bilateral input? which stage of the pathway is it?
superior olivary complex, 2nd
name the 2 types of auditory nerve fibres
low spontaneous rate and high spontaneous rate
which auditory nerve fibre type has a high threshold for activation, is used to being occasionally active and is needed for signal in noise processing?
low spontaneous rate
which auditory nerve fibre type has a Low threshold for activation, is Used to being active for long periods, is Necessary for hearing quiet sounds in quiet environments and forms the Basis of pure tone audiogram (hearing test)?
high spontaneous rate
give the correct name for a hearing test
pure tone audiogram
the descending auditory pathway has …… connections than the ascending, has ……. function, mediates …… attention and auditory ……
more, inhibitory, selective, prediction
which axis is processed mainly by the superior olivary complex for determining the location of sounds?
left to right axis (azimuth)
which axis is much less accurate and has head/pinna related transfer function in determining the location of sounds?
the front/back and top/bottom
name the gyrus found in the primary auditory cortex? which fissure is it tucked away in?
heschel’s gyrus, sylvian fissure
in which two locations of the brain does the non-primary auditory cortex exist?
superior temporal gyrus and planum temporale
in which brain hemisphere is there temporal processing in speech?
left
in which brain hemisphere is there pitch processing?
right
subcortical auditory electrical brain responses are known as what?
ABRs
cortical auditory electrical brain responses are known as what?
event related potentials (ERP)
which type of auditory brain response is typically elicited by repetitive clicks and is the main basis of hearing assessment in infants?
subcortical ABRs
how would you describe the organisation of the auditory pathway?
tonotopically organised
