Auditory System

Question 1

frequency range for humans (Hz)

Answer 1

20 to 20,000 Hz

Question 2

what is amplitude?

Answer 2

sound pressure levels (loudness)

Question 3

total stimulus energy range humans hear is

Answer 3

10^12, expressed as logarithmic scale (decibels)

Question 4

minimum detectable difference in intensity is

Answer 4

1 dB

Question 5

threshold (in dB) for sense of hearing is usually in what range

Answer 5

15-20 dB

Question 6

external auditory meatus (canal) has resonant frequency range of _____ - ______ Hz

Answer 6

800- 6500 Hz

Question 7

surface area of the tympanic membrane (ear drum)

Answer 7

55 mm^2

Question 8

purpose of the ossicular system

Answer 8

amplifies and transmits vibration from air into fluid

impedance matching

Question 9

oval window surface area

Answer 9

3.2 mm^2

Question 10

what can protect the ear from loud low frequency sounds?

Answer 10

contraction reflex of ossicular muscles

mediated by facial nerve

Question 11

the ossicular system consists of

Answer 11

3 bones that amplify system (malleus, incus, stapes)

Question 12

what does the inner ear consist of

Answer 12

cochlea, membranes, fluids, organ of Corti, spiral ganglion

Question 13

length and turns of human cochlear

Answer 13

35mm long, 2 1/2 turns

Question 14

perilympth is found in:

Answer 14

• scala vestibuli

- scala tympani

Question 15

endolympth is found in:

Answer 15

scala media (cochlear duct)

Question 16

perilymph is similar to what type of fluid

Answer 16

normal extracellular fluid (high Na+)

Question 17

endolympth is high in what ion

Answer 17

K+ concentration

Question 18

the organ of Corti sits on what membrane?

Answer 18

basilar membrane

Question 19

what membrane codes for frequency

Answer 19

basilar membrane

Question 20

basilar membrane base (largest part) is for ____ frequencies

Answer 20

high

Question 21

basilar membrane apex (smallest part) is for ____ frequencies

Answer 21

low

Question 22

vibration of the basilar membrane results in

Answer 22

“rocking” of organ of Corti

Question 23

since endolymph in the scala media has high [K+], the total membrane potential difference at tops of hair is

Answer 23

-150 mV

Question 24

endolympth is ____ mV relative to perilympth

Answer 24

+90 mV

Question 25

movement of hair in tectorial membrane opens _____ channels, entrance of _____ causes depolarization

Answer 25

K+

Question 26

synapse at base of hair cell with nerve ending triggers what?

Answer 26

action potentials

may use glutamate

Question 27

inner hair cells synapse on multiple endings for detection of:

Answer 27

detail

Question 28

outer hair cells function is for

Answer 28

detection

Question 29

which is more important: inner or outer hair cells?

Answer 29

inner hair cells

Question 30

which is more abundant: inner or outer hair cells?

Answer 30

outer hair cells

Question 31

which is closer to spiral ganglion: inner or outer hair cells?

Answer 31

inner hair cells

Question 32

how is the amplitude (loudness) encoded?

Answer 32

by number of action potentials and increasing number of fibers stimulated

Question 33

for ___ frequencies (

Answer 33

low (<2000 Hz)

Question 34

for the auditory pathway, where do the spiral ganglion axons synapse?

Answer 34

in cochlear nuclei in rostral medulla

Question 35

in the auditory pathway, what local relay sends feedback to the cochlea

Answer 35

superior olive

Question 36

what is the local relay for auditory pathway head and eye movements

Answer 36

inferior colliculus

Question 37

what adjusts the sensitivity of hair cells

Answer 37

feedback (olivocochlear bundle)

Question 38

what is the VIII primary afferents

Answer 38

spiral ganglion axons

Question 39

in auditory pathway, cochlear nuclei bilaterally go to inferior colliculus though the:

Answer 39

lateral lemniscus

Question 40

due to the bilateral pathway, brain stem lesions above _____ do not product unilateral hearing loss

Answer 40

medulla

Question 41

auditory cortex in superior temporal gyrus is Broadmann areas:

Answer 41

41, 42

Question 42

auditory pathway, inferior colliculus goes to ______ though brachium of inferior colliculus

Answer 42

medial geniculate in the thalamus

Question 43

medial geniculate axons ascend to

Answer 43

auditory cortex in superior temporal gyrus

Question 44

what organization occurs within the lateral fissure

Answer 44

tonotopic (frequency) map running medial to lateral