Audition Lec25 Flashcards
what are the 3 divisions of the cochlear nuclei
the dorsal, posteroventral and anteroventral nuclei.
the whole range of ____ transduced by the cochlea is represented in each of its three nuclei.
frequencies
one ___ = a sine wave
tone
oval window is smaller than tympanic
membrane –>
20x pressure increase
lever action of ossicular chain –>
___x force increase
1.3
- from base to apex there is an increase in
width by a factor of 10
- from base to apex there is a decrease in
- stiffness
- frequency
- conduction velocity
how are hair cells at the apex compared to the base?
LESS stiff and LONGER
High frequency = higher amplitude = ___ distance traveled
shorter
___ frequencies go farthest on the basilar membrane
Low
Auditory receptor cells at each point along the basilar membrane respond to the amplitude of the traveling wave that ___
reaches it.
Hair cells spontaneously oscillate & are most sensitive to sound frequencies which
match their oscillation frequencies
The ___ membrane is connected to the basilar membrane via the rigid limbus
tectorial
Pushing up the basilar and tectorial membranes shears the cilia in one direction, which opens __channels and depolarizes the cell
K
what is the normal potential difference between the sacla media and hair cell interior
150 mV
(scala media = 80 mV, hair cell interior = -70 mV)
what pushes K+ into hair cells?
The scala media’s high (+) potential electrochemical gradient (150 mv)
what range of frequencies does the 3 cochlear nuclei receive?
each nucleus receives the full
range of frequencies
what type of pitch does the auditory cortex receive?
pitch patterns but necessarily pitch
Cochlear prostheses bypass the hair cells and excite the___
appropriate nerve fibers.
general method of cohclear implants is to pass multiple electrodes into the ___
Scala Tympani.
The auditory system respond to a series of rapid fluctuations in______ brought about by the rarefaction and compression of air molecules.
air pressure
the greater the magnitude of the amplitude of the sound the greater the
physical magnitude of the sound.
how much of the incident energy is transmitted at the oval window
1/1000
in decibals how much sound is lost by the time it reaches the oval window
30db
At the oval window, only about 1/1000 of the incident energy is transmitted.
To compensate for this loss requires an approximately ___ increase in pressure
32-fold
The 32-fold increase is accomplished in the ___ ear,
middle
The effective area of the tympanic membrane is about 60 square millimeters and that of the oval window about 3 square millimeters.
This results in a ___-fold increase in pressure at the oval window.
20
he force at the oval window is not equal to the force applied at the tympanic membrane but actually exceeds it by a factor of
1.3.
As a result of forced applied at 1. the oval window 2. at the tympanic membrane
the pressure at the oval window is increased by a factor of ___
26.
with tympanometry
In conductive hearing losses more sound is ____ then in the normal middle ear.
reflected
Pathologies that result in conductive losses:
- otitis media
- otoschlerosis
- ear wax build up
the basilar membrane ___ in width as it runs from the base to the apex of the cochlea.
increases
For equally applied forces along the membrane regions of lower stiffness will be displaced to a _____ degree.
greater
The decreasing stiffness from base to apex results in an increase in___ from base to apex.
phase lag
As the stapes moves into the oval window a volume of the____is compressed.
Scala Vestibuli
the body compensates for the compression of the Scala Vestibuli by
bulging out of the round window.
downward bulge of round window is reet to a neutral position by the resotrative force provided by the
stiff base
the greater the frequency of the sound wave, the less the distance the
traveling wave will move along the basilar membrane.
The character of the traveling wave, including its points of maximum deflection, is perfectly reflected in the
pattern of discharges transmitted by the primary auditory neurons.
It turns out that the peak displacement of the traveling wave is actually very narrow, about the=
width of a few hair cells
where is the organ of corti?
the basialr membrane
___ houses the auditroy receptors
organ of corti
Pushing the basilar membrane and the tectorial membrane up will put a ___ action on the cilia in one direction
shearing
Electrophysiological recordings have shown that there is a potential difference of +80 millivolts between the ___ and the ___
scala media and ground.
he inside of the hair cell is about ___ millivolts.
-70
Hair cells at different points along the basilar membrane differ from one another in their ___
electromechanical properties.
The frequency at which different hair cells oscillate differs according to their __
position along the basilar membrane.
____ is apparent in that each 8th nerve fiber terminates within the cochlear nuclei by branching to each of its three divisions:
Parallelism
High frequencies are represented ___ in the nuclei
dorsally
Within area AI, neurons of similar best frequency are arrayed
in a strip or belt-like
Within area AI, neurons of similar best frequency are arrayed in a strip or belt-like
structure that runs perpendicular to the___ axis.
high-to-low
frequency tonotopic
___-dimensional spatial organization in
the auditory cortex.
three
