Auditory 1

Question 1

Sound comes in the form of ___ created by

Answer 1

pressure waves

increases and decreases in air pressure (compression and rarefaraction of sound wave)

Question 2

Sound has 2 distinct qualities that contribute to audition

Answer 2

1) intensity (loudness)

2) frequency (pitch)

Question 3

Intensity coresponds to __, measured in

Answer 3

pressure compressing air of sound wave

measured in dB SPL

normal = 7-8 orders of magnitude

Question 4

Equation for intensity of sound

Standard reference Pressure =

Normal auditory threshold =

Answer 4

dB SPL = 20 log(P1/P2)

Standard reference pressure (P^2) = 20X10^-6 N/m2

Normal auditory threshold = 1000 Hz

Question 5

Frequency define

measured in ___

normal range for human =

Answer 5

freq = # of times per second sound wave reaches peak compression (max intensity) or rarefraction (min intensity)

measured in Hz

range = 20 Hz - 14 kHz

Question 6

Define auditory threshold

Answer 6

lowest intensity of sound heard by human ear at given freq

Question 7

Describe audiogram axes

how do you perform audiogram

Answer 7

X-axis = freq
Y-axis = intensity 

play series of tones for patient of progressively lower intensity at each freq

patient says when they hear tone and lowest intensity tone (and correspond freq) plotted

Question 8

what is normal hearing in relation to auditory threshold

dramatic decline in auditory threshold (another way of saying it?)

Answer 8

normal hearing = relatively constant auditory threshold ~0 at all freq

incr in minimum intensity of sound detected

Question 9

Acoustic impedance mismatch describe

Answer 9

differences in impedance btwn middle ear and inner ear
= resistance to flow

fluids > impedance than air

Question 10

what is importance of differences in impedance

how does ear compensate

Answer 10

sound wave moves from air to fluid, significant portion of wave deflected at interface (approx 30 dB intensity lost)

ear compenste for loss of impedance with ossicles

Question 11

three ossicles (med to lateral)
connecting what to what

what is function?

Answer 11

stapes, incus, malleus
connecting TM of middle ear and oval window (connection btwn inner and middle ear)

bones amplify intensity by ~28 dB to compensate for intensity loss

Question 12

amplification by ossicles is result of ?

Answer 12

1) pressure sound wave from TM concentrated on to much smaller surface of stapes

P = F/A so decr A, incr P or intensity

2) middle bones like lever to incr force transmit to inner ear

Question 13

Sensorineural vs conductive hearing loss

Answer 13

conductive hearing loss = damage to elements of mechnaical transmission of sound waves thru ear (canal, TM, ossicles)

Sensorineural hearing loss = damage to hair cells or nerve fibers

Question 14

causes of sensorineural hearing loss

Answer 14

XS loud noises
ototoxic drugs
age = presbycusis

Question 15

causes of conductive hearing loss

Answer 15

otitis media= fluid disrupt conduct
otosclerosis = ossicles not move well
atresia = ear canal misshape
perforation/rupture TM
incr pressure in mid ear with altitude

Question 16

How does sound elicit movement of basilar membrane to cochlea

Answer 16

1) sound thru middle ear
2) amplify by ossicles
3) transmit to oval window
4) window opens into cochlea

Question 17

How does sound transmit from cochlea

Answer 17

5) pressure sound wave compresses fluid in scala vestibuli causing downward movement of BM
6) compresses fluid in scala tympani and bulges round window

or
6) transmit from vestibuli to scala tympani via helicotrema

Question 18

Parts of cochlea

Answer 18

1) scala media (separated from scala tympani by BM)
organ of Corti (inner hair cells) sit on top of BM in media

2) scala tympani
3) scala vestibuli

Question 19

What is helicotrema

Answer 19

hole in basement membrane connecting scala vestibuli and scala tympani

Question 20

How does compression and rarefaction differ at BM?

Answer 20

compression = incr pressure and follow sequence

Rarefaction = pressure drops and sequence reverses

Question 21

what is a tonotopic map?

Answer 21

basilar membrane not uniform

wave generated by compress oval window not symmetric wave with compress/rarefaction of same amplitude –> created by base, apex, intermed basilar membrane

Question 22

distinguish btwn base, apex, and intermediate parts of basilar membrane structurally

Answer 22

base = near oval and round window = small and rigid

apex = large and “floppy”

intermediate = in btwn

Question 23

distinguish btwn base, apex, and intermediate parts of basilar membrane in terms of freq

Answer 23

base = highest amplitude with high freq

apex = low freq

intermediate = in btwn

–> creates tonotopic map

Question 24

hair cells sit on what?

inner hair cell 
- name of projection? 
- send where and contact what
- base vs tip surrounded by? 
-

Answer 24

hair cells sit on BM within organ of corti of scala media (both inner and outer)

sends stereocilia into scala media to tectorial membrane and surrounded by K+ fluid = endolymph

base surrounded by K+ low fluid = perilymph

Question 25

why do hair cells along BM rspond to diff freq

Answer 25

inner hair cell move in response to movement of BM

since portions of BM are vibrated max at certain freq, hair cells also respond based o position on BM