audition (25)

Question 1

in simplistic terms, how do cochlear prosthetics work?

Answer 1

they bypass the hair cells & excite the appropriate nerve fibers

Question 2

what does the auditory system respond to?

Answer 2

a series of rapid fluctuations in pressure brought about by the rarefaction & compression of air molecules

Question 3

what does the maximum of the sine wave (in a pressure as a function of time plot) correspond to?

Answer 3

the greatest density or pressure

Question 4

what does the amplitude in a pressure as a function of time plot represent?

Answer 4

the magnitude of the pressure change

Question 5

what does the “decibel” compare?

Answer 5

it comes the physical magnitude of any given sound to a standard physical magnitude

Question 6

how is the standard physical magnitude chosen?

Answer 6

it is one near the normal human threshold for tones to which humans are most sensitive

Question 7

at the oval window, how much of the incident energy is actually transmitted

Answer 7

only 1/1000

Question 8

to compensate for the loss of energy at the oval window, how big of an increase is there in pressure?

Answer 8

32 fold increase in pressure

**some confusion on this in the notes, listing different values for increase in pressure.. holler if you understand this

Question 9

what are some pathologies that could result in conductive losses?

Answer 9

otitis media (middle ear infection), otosclerosis (fixation of the middle ear ossibles) and ear wax buildup in the external ear canal

Question 10

what is tympanometry?

Answer 10

clinical technique that measures the impedance of the middle ear to sound

Question 11

what is the membrane in the cochlea called?

Answer 11

the basilar membrane

Question 12

what does the analysis of the frequency of sound depend on?

Answer 12

on the way the sound waves affects the basilar membrane

Question 13

as you travel from base to apex on the basilar membrane, what happens to its width and stiffness?

Answer 13

increases in width and decreases in stiffness

Question 14

for equally applied forces along the membrane, will regions of higher or lower stiffness will be displaced to a greater degree?

Answer 14

regions of lower stiffness

Question 15

what does a decrease in stiffness from the base to the apex result in?

Answer 15

a increase in phase lag

Question 16

what does the distance of a traveling wave depend on?

Answer 16

depends upon the frequency of the sound wave producing that traveling wave

Question 17

how is the traveling wave produced?

Answer 17

1. As the stapes moves into the oval window a volume of the scala vestibuli is compressed
2. The downward bulge initially occurs near the applied pressure at the base
3. The stiff base provides a restoring force that brings the membrane back to a neutral position
4. this requires that the volume of compressed fluid is taken up elsewhere & shunted farther along the membrane to a less stiff region on and so
5. whem the stapes moves out, an upward bulge is produced which, following the downward bulge produces a full traveling wave

Question 18

in regards to distance traveled, what does a greater frequency of a sound wave correspond with?

Answer 18

less distance traveled along the basilar membrane

Question 19

how are auditory receptor cells stimulated?

Answer 19

they are MECHANICALLY stimulated by the displacements of the traveling wave

Question 20

what are 2 ways to increase the excitation of any auditory nerve fiber?

Answer 20

1. by presenting a sound wave frequency with a peak traveling wave displacement nearer the position of that fiber’s receptor cell
2. within limits, you can increase the intensity of the sound wave

Question 21

which structure houses the auditory receptors?

Answer 21

the organ of corti

Question 22

where is the organ of corti located?

Answer 22

it rests upon the basilar membrane

Question 23

what is the potential difference between the scala media and the ground?

Answer 23

+80 mV

Question 24

what is the potential difference across the reticular lamina?

Answer 24

150 mV

Question 25

what does the shearing action of a wave do to a cilia?

Answer 25

it alters its permeability (the resistance) of the auditory cell membrane allowing for a change in current flow

Question 26

what does the magnitude of the shearing force depend on?

Answer 26

depends upon the magnitude of the basilar membrane displacement

Question 27

how do hair cells at different points along the basilar membrane differ from one another?

Answer 27

in the electromechanical properties

Question 28

what are the properties of the hair cells and their cilia at the base of the cochlea?

Answer 28

narrow & stiff

Question 29

what is the role of the central auditory system

Answer 29

interpret the discharge patterns of the auditory nerve fibers in order to produce the perception of sound

Question 30

what are the 3 divisions of the cochlear nuclei?

Answer 30

• dorsal
• posteroventral
• anteroventral

Question 31

where in the nuclei are high frequencies represented?

Answer 31

dorsally in each of the nuclei

Question 32

where is the nuclei are low frequencies represented?

Answer 32

ventrally in each of the nuclei

Question 33

where is the primary auditory cortex?

Answer 33

it occupies the transverse temporal gyrus and is largely buried in the sylvian fissure

Question 34

how are neurons arranged in area A1?

Answer 34

-Neurons of similar best frequency are arrayed in a strip or belt like structure that runs perpendicular (aligned dorsoventrally for A1) to the high to low frequency tonotopic axis

Question 35

true or false?

the auditory cortex is involved in pitch itself rather than patterns of pitch

Answer 35

FALSE

the auditory cortex is involved in PATTERNS of pitch

Question 36

what were the conclusions for the training paradigm for cat discrimination experiment?

Answer 36

• that the auditory cortex does not seem necessary for pitch discrimination
• auditory cortex is move involved with the analysis of pitch patterns than pitch itself