Exam 2

Question 1

Tympanometry

Answer 1

dynamic measurement of middle ear function.

tracks admittance during changes in ear canal pressure

Question 2

Tympanogram peak pressure

Answer 2

maximum air pressure in a tympanogram

Question 3

tympanometric width

Answer 3

pressure range over which the tymp attains 50% of its peak in admittance.

Question 4

ASR

Answer 4

acoustic stapedius reflex

requires functional cochlea, 8th cranial nerve, brainstem, 7th cranial nerve, and normal middle ear

Question 5

ATF

Answer 5

Acoustic transfer functions

used to meausre responses in the ears of adults and kids

Question 6

clinical signal detection of conductive hearing loss

Answer 6

impaired ears fell out of the 10th-90th percentiles of normal responses. so they created an error function to predict conductive HL using tymp and ambient-pressure energy absorbance responses

Question 7

laser doppler vibrometry

Answer 7

relatively new technique that is also being used to make wideband measurements of middle ear function

Question 8

calibration for tymps

Answer 8

3 cavities: .5, 2.0, 5.0 from ANSI S3.39

Question 9

constraints of tympanometry

Answer 9

1. acoustic immittance measures the acoustic energy that flows INTO the middle ear, and no what flows THROUGH the middle ear to the cochlea. some energy is lost or absorbed before the cochlea. cannot use tymps to regard hearing sensitivity.
2. when immittance probe is sealed into the ear canal, measurements are made into a virtual “black box”. cant be used to determine middle ear structure/s in the ear contributed to change in stiffness or change in mass.

Question 10

Tympanogram width

Answer 10

most common measure to describe the sharpnes of the tymp peak.
. Take height of peak and come down half way and see how wide it is.
• There were hopes that using the width we could tell about the conditions of the middle ear but that never panned out. So now we move on to acoustic reflexes

Question 11

Low admittance = ?

Answer 11

MEE, otosclerosis, thickened ear drum, malleus fixation

Question 12

High peak Ytm = ?

Answer 12

trophic scarring, tympanosclerotic plaques, ossicular replacement prostheses, ossicular discontinuity

Question 13

abnormally high peak Ytm =?

Answer 13

medical referral when there is significant conductive/mixed hearing loss

Question 14

Effects of gender, age, and race

Answer 14

females: broader and lower peak
chinese: increase in TW in chienese adults possibly because of smaller body size. 48% of chinese kids failed tymp when white kids were normal
Kids < 1yr; broader TW and lower Peak Ytm (maybe from residual effects of otitis media)6

Question 15

what does frequency depend on?

Answer 15

stiffness and mass. these determine what its period of motion should be

Question 16

impedance

Answer 16

opposition to the transport of energy through a medium. Impedance can be measured in different types of media like mechanical system, electrical, or acoustic.
 how do we get to impedance? You need force to move anything/create motion…so the easiest example is using force (F) in a mechanical system. Electrical is Voltage (V). acoustic needs pressure to move anything (P)
 next. We calculate the impedance of each system. Take force divided by velocity and whatever we get out of it is the impedance/opposition.
PRESSURE over VOLUME VELOCITY

Question 17

Reactance

Answer 17

putting in energy at the entrance of the ear drum, and getting SOME at the stapes. If it was perfectly efficient then we would get all we put in into the oval window. But we don’t. why are we losing energy? What is causing it. There are some elements that contribute to resistance and some that contribute to reactance. Reactance conserves/keeps it. So that part of the energy doesn’t show up at the other end. Resistance dissipates and could turn to heat or whatever. But whether its kept or dissipated, it doesn’t make it to the other end. Resistance can be more of less friction. So anything that is vibing in air, you have friction cuz its vibing against the air molecules.
 Reactance is the contribution of the mass and stiffness to conserving energy.

Question 18

How does mass and stiffness of a system depend on frequency?

Answer 18

Why freq? cuz the impedance of a system is not independent of freq. any given acoustic system is more or less efficient at a certain freq. that change is primarily controlled by mass and stiffness

Question 19

reflectance

Answer 19

• an idea of how efficient the middle ear is in transporting sound across a range
•  Instead of having a pressure axis on x like tymps, you would have freq. so several are working to see if this is more efficient. Where we are today is to say where is the normative range. 100,200,1000 people…what is the 95% confidence interval. Problem 1: defining normal confidence interval. 2nd: when I have a pathology (otosclerosis, ear drum hole) u have to garuntee that that line will fall outside the normal confidence interval. Otherwise the test cant perform. By looking at the reflectance u wouldn’t get the info the tymp is giving u today. Reflectance is hard to measure. How much comes back? Ratio is the reflectance. So in a hard wall cavity youd put in x and get back x cuz nothing would go thru. So conceptuatlly its easy to grasp. Whether its clinically useful is still on the table.

Question 20

what roles does the middle ear play in reflexes?

Answer 20

has to let sound through; reflect actually happens in the middle ear so we have to be able to detect it. You cant get a reflex if the cochlea doesn’t work.

Question 21

what happens when the middle ear is full of fluid in terms of reflex?

Answer 21

If its full of fluid then the stiffness is already raised…so you cant see whats happening. Stiffness is already at max. if fluid in the R ear…u could get to cochlea and send the reflex over to the L ear. 2 complicating things with reflexes: neurons work or they don’t…so if anythings wrong there youre screwed. But if theres something wrong with the middle ear even tho its really really small, it becomes very hard to see the reflex even tho it happens (if it happens). 2nd is for purely cochlear losses. The loss keeps getting bigger and biger and likelihood of getting reflex gets smaller and smaller. However, we have recruitment. Abnormal growth in loudness (“cant hear, cant hear, too loud!”). this is a tell tale sign of pure cochlear loss.

Question 22

Hermetic seal

Answer 22

 So now the hermetic seal becomes important. Its important because without having this you cant change the pressure. But ALSO you need the seal to keep everything on the right side of the seal.

Question 23

what measures can you pull from tymps?

Answer 23

 Now there are many measures that get pulled from the tymp. Imagine a tymp. Peak is right around 0, the two tails are where they should be..whats the first thing you wanna pull out of this graph? Peak pressure (find the peak and draw a line to the x axis). Where do you expect the peak pressure to be? At or near 0. What will you tolerate? Page 161 Table 9.1. youll find 2 interesting tables. Each row in that table is a paper from the literature that gives you normative data for everything we talk about today. The funny thing is that nothing says the same thing. At some point you have to pick what you go with. The narrow the range, the stricter the criteria is. So what is the danger of picking a narrower and narrower range? Well the narrower the range that you consider normal, the more chances any given ear will fall in the given category. The narrower the normative range, the greater the probability that something will fall in that category. Typically with a narrow ranger, you over diagnose.
• Now, with a large range…the problem is opposite. The larger the range, the greater the probability that an abnormal ear falls within that range. So when u have a range too large, you increase probability of missing a disease. So u go from possibly over diagnosing to under diagnosing.
• You will find out what your preceptor thinks is a normal range and just smile and agree

Question 24

can peak pressure fall outside of the normative range? why? under what circumstances?

Answer 24

• Blocked Eustachian tube: pressure in middle ear is negative. Oxygen gets eaten especially if you have a middle ear disease. The peak pressure could be negative. What type of tymp would jerger call this? Type C!
• Peak pressure is one of the most useless piece of the tymp puzzle. Why? Because its not very sensitive.
• Peak pressure is useful tho to work backwards from the E. Tube and see if its working. Peak pressure changes if you force air into the middle ear or force air out of the middle ear. So when you ask them to swallow or blow they need to hold nose/keep mouth close to keep pressure where you want it.
• How much of a change do u accept to be reliable? 10-15 decapascals. But if its for an official test you should do a test-retest to make sure
• Blocked Eustachian tube: pressure in middle ear is negative. Oxygen gets eaten especially if you have a middle ear disease. The peak pressure could be negative. What type of tymp would jerger call this? Type C!
• Peak pressure is one of the most useless piece of the tymp puzzle. Why? Because its not very sensitive.
• Peak pressure is useful tho to work backwards from the E. Tube and see if its working. Peak pressure changes if you force air into the middle ear or force air out of the middle ear. So when you ask them to swallow or blow they need to hold nose/keep mouth close to keep pressure where you want it.
• How much of a change do u accept to be reliable? 10-15 decapascals. But if its for an official test you should do a test-retest to make sure`

Question 25

ear canal volume

Answer 25

• Lets back up a whole lot to the 1950s. they worked on if you take a hard walled cavity and that sound cant escape or enter, can you tell what the volume of air is in that cavity, can you tell the volume? Yes. Relatively well. So they came up with this exercise of putting a probe in a 2cc cavity. Drive speaker with x amount of energy. And we have a mic and we’ll measure how much sound we generate. Then do it again at a 5cc cavity. The ratio between these two sound pressure levels should be proportional to the volume between the 2 different types of cc’s. you can get a sense of how much sound pressure you can expect provided you stimulate with energy x. so that caught on and today you have at least 3 calibration cavities per machine. What you do is take probe and put it in the smallest all the way up to get the ratio. Now put the probe in ear canal and don’t know the volume but I stimulate with energy x and get information. Compare to calibration data to the unknown cavity. Predict what the volume of this cavity should be. What is the equivalent volume of air to that cavity? • You needed a hard walled cavity for this, remember. Because you stimulate the speaker with xvolts and don’t want the energy to escape, but rather turn into sound pressure to measure it. This doesn’t happen in the ear canal! So what are we gonna do about this? How are we going to get a measure of the volume of the ear canal?  Pump a bunch of air in there, push the TM so it’s hard as a rock/stretched out so it can’t move…and the volume u get is the volume of the ear canal. However, you could suck all of the air out too to make it taught the other way. Which one should we do? The negative tail would be smaller. So should we take an average, one, or the other? It doesn’t matter..as long as you can all agree to do it the same way. That’s what has happened. Take pressure at the negative tail and that is going to be the equivalent ear canal volume. The air sucked out is negative. Negative  100

Question 26

whats the clinical value of knowing ear canal volume?

Answer 26

 If the ear canal volume is larger than the ear drum could be perforated and youd be measuring the middle ear too. • The other way: if its too small it could be a cerumen blockage or some other object. Something that occupies space. • Bigger volume = measuring bigger than the ear canal. Smaller = something in the ear.

Question 27

Compensated peak compliance or admittance

Answer 27

* Height of the peak. Draw a line from the peak onto the y axis we get the height which is peak compliance. * Why compensated? So you’ve got this peak in the tymp. What does the full height to the peak represent? Where the most energy is being passed through. Extreme of the argument: at peak pressure all of the energy is going thru. So the height is the volume of what? We think that the 2 edges are low cuz were keeping all of the sound in. so now at the peak were saying weve made it at flaccid as possible so all of the sound is going into the middle ear…so ear canal and middle ear is getting measured at the peak. The hard wall is now the stapes. So we get the volume of both now! How do we figure out just the middle ear from here? Subtract the edges to get the COMPENSATED peak compliance.

Question 28

tympanogram height

Answer 28

Table 9.1 in adults it could be anywhere between these two ranges. 0.21.8. that’s all acceptable. Why would it be smaller than that? If its full of fluid/not much volume in there.

Question 29

Tymp Type As

Answer 29

Otosclerosis could cause this! Anything that is weighing down the vibrations of the middle ear chain so you have very little in terms of the peak and the tymp. That’s a SHALLOW

Question 30

Tymp Type Ad

Answer 30

 Something that was binding before, is now cut loose or or tymp that is lost 2/3 layers of tissue so its really flappy. Something that has increase the movabilty in the chain. DEEP

Question 31

Tymp Type B

Answer 31

FLAT--If its full of fluid/not much volume in there. Aka you cant move the TM.

Question 32

Tymp Type C

Answer 32

peak at the right height but at the wrong pressure. Typically way negative

Question 33

Static compliance and peak pressure

Answer 33

 This classification system is built on static compliance and peak pressure. You have other measures at your ahnds tho! Equivalent ear canal volume (not ever type B is the same. A type b tymp with normal ear canal volume might be fluid in the middle ear. A type b with a large EAV volume might be perforated ear drum. A 3rd type b with a minute ear canal volume could be something in the ear.

Question 34

Why do we test with speech audiometry?

Answer 34

 Why do we test?  Hearing speech is what people want to do most! So test speech with speech. • Speech is the essence of communication so we need to pay attention to how people are responding to speech. This also creates a problem. So what are you going to use to evaluate the speech perception? You can fill in the blanks with context cues with sentences, but with words its more difficult. You can extend that farther and you could use nonsense syllables to take out lingustitical and cultural context.  Tests cognition, memory, muscle control, speech production, etc.

Question 35

what are we going to measure with speech audiometry?

Answer 35

 1 set of tests near thresholds and one near suprathreshold (more for communication). You test both to compare them. Combining points…we do two layers of evals. One we want perceptual thresholds (like pure tones). This kind of evaluation is called speech detection/perceptual thresholds and the idea is simple, how loud does speech material have to be for you to get it right 50% of the time. On the other hand, in suprathreshold testing, you want to find out if a speech signal was audible (no problem in EHARING the signal), what is the accuracy at which this person perceives this word. This is a discrimination SCORE (not threshold). Need quiet background. Should be 5, 6, or 7dB difference between them.  Might not match if: • Cognitive problem -- Neurons firing, no association being made • Faker

Question 36

Normal bandwidth of speech?

Answer 36

 What frequencies does speech have energy in? what’s a normal bandwidth of speech? Wheres the most energy, where does it start, where does it end? Constonants are higher in freq but lower in intensity.

Question 37

Articulation index

Answer 37

AI-- : for given audiogram you come up with a percent. For an example lets say that 64% is audible. Or .64. then youll see that there is hearing aid fitting software that will predict how the artic index will change. You can increase it by a certain number (lets say .78 now). • 1 step farther is the ANSI standard which is the Speech intelligibility index (SII). What this does is breaks up the entire range of hearing into tiny bands of frequency. You can do this in 3rd octave bands or 8 octave bands. You can assign a number to each band like “in this band there is x amount of speech information”. To a person nothing else was audible except that band of frequencies…they will understand X % of speech. All bands add up to 100%. So full SII = 1. Depending on how much hearing loss you have where your SII might go down. Or if you take full bandwidth speech and filter some parts out, you might artificially change the SII for that particular signal. So between AI and SII you should be able to relate back to what kind of audiogram would result in what kind of speech respeiction/word req score. Its related to which frequencies are we missing.

Question 38

Spondee words

Answer 38

Like northwest, toothbrush. Not hard to administer! All you have to do is read out the words at a clearly audible signal. Then just start dropping like youre doing an audiogram until you get to 50%. Everyone does this differently! Know what your clinic wants done. You just wanna find a dBHL of 50% performance. Is that all you can do? What if you did multiple levels of phonetically balanced words. Would that give you any information? • You could get 50% correct for words, nonsense, stories, etc. and to do that you would have to get something like an S shaped graph between % correct and presentation level. What would happen if you use sentences instead of spondee words?  Maybe youd switch thresholds because you had longer time to process.  Whole point: pay attention to threshold AND slope

Question 39

Performance intensity

Answer 39

We will use them more in the next step. Now we have 50% correct, presentation level aka SRT (speech repection threshold) now we do a word recognition test. The purpose is to make sure that the signal is audible and then figure out how much of it can be understood. So whats the presentation level going to be? 30-40 above. Doesn’t matter how much above, but substantially above. Now the big difference between threshold testing and figuring out word req score is that you don’t alter presentation level. Ure interested in finding out at any given presentation level, what is the performance. How many % do they get correct.

Question 40

What kind of words are we going to use for word recognition?

Answer 40

“say the word LAUD”  Supposed to represent the phonetic distribution of the English language. So you should get whatever % you get right of the English language regularly. so now we need standard lists cidw22 = phonetically balanced (sounds) nu6= phonemically balanced (place in the word/word position)

Question 41

NU6

Answer 41

phonemically balanced (word position)

Question 42

CIDW22

Answer 42

phonetically balanced (sounds)

Question 43

Why do we need to do masking?

Answer 43

 It’s how we check to make sure were testing the ear we want to be testing. Stimulus for 1 ear could be stimulating the other ear as well. We are putting a stimulus in 1 ear that is intended for that ear, but it is stimulating the opposite ear. • Is this stimulation in any way different from the nature of acoustic simulation if you were trying to test their hearing? • Because we don’t have earphones sitting in the non-test ear, the signal is getting there through BC. Once it gets there, does it not send a traveling wave or send info to the auditory nerve? Yes. So it’s the same. Even tho the signal is coming from the other side of the head, once it enters the cochlea, it is essentially the same only as if you were putting a softer tone into that ear.  So we have an unwanted tone in 1 ear and we gotta kill it. That’s the whole purpose of masking. We don’t want the stimulation from the 2ndary tone to be perceived as sound.

Question 44

How do we kill sensation of secondary tone?

Answer 44

 We could use white noise, speech, another tone, or whatever you wish to kill the tone.  So what is the underlying physiology that were tapping into to kill this tone? How are we preventing the brain from hearing this tone? • Forget about critical band or anything else. We’re trying to force the basilar membrane to be too “busy” to do anything else. We’re creating a mechanical interference. Suppresser takes over the basilar membrane. • In clinical masking, the detector is your brain. Your brain was detecting a probe…and could PROBABLY decide which ear its coming from…but to be sure we need to kill that probe signal in the non-test ear to help the brain out. • The whole goal of clinical masking is to have enough interference noise/tone/masker that prevents sensation of probe in the wrong ear but doesn’t interfere with perception in the correct ear.

Question 45

Under masking

Answer 45

don’t have interference signal loud enough to interfere effectively with the probe.

Question 46

over masking

Answer 46

you’ve got plenty of masker, but its too much so its interfering with perception of probe in the test ear.

Question 47

How do we mask?

Answer 47

inducing mechanical interference on the basilar membrane

Question 48

Central masking

Answer 48

 How does it happen?  You put in noise/masker and them asker is not big enough to cause a mechanical interference, but what it does is it evokes an efferent response. The efferent neurons go from brain  elsewhere. They can play an inhibitory role. They can reduce vibration by turning down cochlear amplifier, they can produce neural inhibition…so central masking is a catch-all term that people have used to characterize the volume control from the neural pathway. In clinical masking we don’t really worry about central masking. We’d rather use mechanical interference.  Trying to prevent sensation of the tone. How are we going to do it? Create mechanical interference.

Question 49

Tone on Tone separation

Answer 49

mechanical interference

Question 50

masker on tone suppression

Answer 50

mechanical interference

Question 51

cochlear amplifier

Answer 51

works over a narrow range around the characteristic frequency;  So the dotted line signals are still over driven by the solid line in our notes.  So you would need a lower freq. at higher intensity to mask.  As you bring the masker becomes closer the signal, the masker becomes more effective.  For a masker to be effective, it has to be within the same critical band of the probe. Even when we do that, its easy to see that maskers on either side will not have a symmetric effect on the probe. Low masks high better than high masks low

Question 52

why not just put in all kinds of tones to create a narrowband noise?

Answer 52

* Noise w/in critical band will mask the probe. So you can have a masker. You could have a wide band..but the wider the band than the critical band the energy becomes wasted. * Because we know that the width of the masker is only effective to a certain extent…we use a 1/3 octave band masker. * So if you have a tone at 1khz, you turn on masking and…and every audiometer today is centered around 1khz with a 1/3 octave band narrow band noise. * So we have just said that the bandwidth of a masker is an important variable because when you quantify the level of a masker, you quantify the overall SPL. Their masking efficiency stays the same.

Question 53

level per cycle

Answer 53

how much energy is captured in every 1Hz bin of that noise. So if you have a signal that’s wide and then make is smaller, there’s more energy in the smaller band. Think of particles in a jar getting squished. The more u squish, the closer they are.

Question 54

whats the level per cycle of a given noise?

Answer 54

Its overall SPL – 10log 10 (Bandwidth) |  You can now take very gross examples and tell the difference. Look at notebook

Question 55

why not make the bandwidth infinitely small?

Answer 55

 You want the masker to sound different than the tone. |  The standard piece of noise we can get our hands on is the narrowband noise.

Question 56

Whats the masking efficiency/energy in any given bandwidth of noise?

Answer 56

MM (minimum masking) = PL (presentation level)- IA + ABG (air bone gap)

Question 57

Questions to ask to decide if masking is necessary

Answer 57

1. How much signal do i have 2. how much will you lose with earphones 3. how much comes to the cochlea 4. Need to mask? 5. Whats the minimum masking 6. is there a leak/difference between middle/inner ear?

Question 58

otosclerosis

Answer 58

progressive disease manifesting in early adulthood that results from abnormal otic capsule bone remodeling. bone gets replaced by highly vascularized bone.diffuses anklosis of th entire circumference of the footplate. HL progresses from mild ow freq conductive loss to flat severe conductive/mixed loss. affects more females than males and is rare in blacks and asians. in less than 1% of population. Lower Ytm and higher F0 than normal ears. increased stiffness. higher admittance. diagnosis based on finding normal0appearing tymps in conjuction with large ABGs, typically greater in the lower freq range. tmps are less effective in identifiying pathologies like otosclerosis that do not directly affect the ear drum. carhart notch. summary: tymps can be normal, abnormally stiff, or have narow TW. combo w/ significant low freq conductive loss with normal TPP and otoscopy and positive fam history

Question 59

ossicular discontinuity

Answer 59

hard to distinguish from otosclerosis on history/otoscopy basis. CT scanning my aid in diagnosis. discontinuity at the incus is common with chronic otitis media and more rarely due to head trauma(trauma like longitudinal fracture in temp bone). (results form decalcification of the long process of the incus, leaving only a fibrous and connecting the incus to the stapes. max conductive HL

Question 60

complications of chronic otitis media

Answer 60

cholesteatoma, eardrum perforation, and otorrhea. surgical intervention in these patients very often is 2-staged to remove the disease and repair the eardrum perforation in 2st and reconstruct ossicular chain with prosthesis.

Question 61

hemotympanum

Answer 61

blood-filled middle ear cavity. can be caused by head trauma

Question 62

ear drum pathology

Answer 62

atrophic scarring secondary to healed ear drum perforation and tympanosclerosis of the eardrum.

Question 63

neomembrane, momomeric eardrum, or atrophic scar

Answer 63

new membrane that can form after a perforation is thinner than the surrounding ear drum because the central, fibrous layer of the eardrum is visible otoscopically, and sometimes so thin thatits hard to differeientiate from a perforation unless the eardrum is placed under pressure during pneumatic otoscopy/tymps

Question 64

tympanosclerosis

Answer 64

inflammatory process in the middle ear produces calcified plaques in the middle-ear space and on the meedial surface of the eardrum. sequela of middle-ear diseas in childhood, and are of little medical consequence in adulthood

Question 65

otitis externa

Answer 65

high-freq tymp, but little effect on hearing. "swimmers ear". presents with significant otalgia, particauly with manipulation of the pinna. moist, edematous skin with squamous debris or purulent material typically is evident with otoscopy. bacteria! if diabetic, require medical referral.

Question 66

otitis media

Answer 66

assicated with immature eustachian tubes is the most common illness among kids receiving medical care. Acute OM presents otalgia and fever wheras COM presents conductive hearing loss and aural fullness. otoscopy could be: bulging, opaque eardrums with air-fluid levels or bubbles in ME. flat tymp

Question 67

middle ear tumors

Answer 67

cholesteatoma | glomus tumor

Question 68

cholesteatoma

Answer 68

squamous(skin) being trapped in the middlea ear or mastoid. could have migrated from the ear canal or from chronic suppurative OM, or as a result from eustachian tube dysfunction. can arise congenitally from embryotic development. can destroy adjacent bone like ossicles, middle/posterior cranial fossa, and bony labyrinth. audiogram shows max low freq conductive hearling loss with decreasing ABG w/increasing freq.

Question 69

glomus tumor

Answer 69

typically benign derived from supporting nerve tissue around the jugular bulbe or in the middle ear. often have pulsatile tinnitus w. conductive or complete HL in 61% of patients. red mass behind TM. minimal low freq ABG. typms atypical with low normal Ytm

Question 70

patulous eustachian tube

Answer 70

ET remains open. people complain about hearing their own voice too loudly.

Question 71

acoustic reflex pathway

Answer 71

bilateral contraction of the middle ear muscles in response to a high-level sound presented in either ear. cochlea to CN VIII to SOC to FN VII to stapedius

Question 72

ipsilateral

Answer 72

UNCROSSED pathway of the stapedius

Question 73

contralateral

Answer 73

CROSSED pathway of the stapedius

Question 74

nonacoustic reflexes

Answer 74

a nonacoustic stapedius reflex is elicited by tactile or electrocutaneous stimulation of most of the areas of skin on the sides of the face and the sides of the head around the pinna, and both the stapedius and tensor tympani muscles are activated when the orbital area is stimulated by an air puff or a quick and sudden lifting of the upper eyelids.

Question 75

middle ear muscle and reflex theories

Answer 75

``` protection theory accomodation theory ossicular fixation theories perceptual theory desensitization, interference, injury protection theory ```

Question 76

protection theory

Answer 76

acoustic reflex protects the cochlea from damage due to overstimulation by lowering the amount of sound energy reaching the inner ear.

Question 77

accommodation theories

Answer 77

the purpose of the middle ear muscles is to modify the conductive mechanism in order to optimize hearing sensitivity in general or to selectivity enhance sounds in certain frequency ranges.

Question 78

ossicular fixation theories

Answer 78

the stapedius and tensor tympani muscles maintain the porper positioning and rigidity of the ossicular chain

Question 79

perceptual theory

Answer 79

the middle ear muscles improve an animals audiotry perception by: 1. smoothing the freq response of the conductive mechanism by the tonus of the intratympanic muscles. 2. improving attention to acoustic environment by varying teh freq and intensity characterics of environmental sounds through modulation of muscle tonus; and 3. attenuating the animals low-freq interanl sounds w/o reducing the high freq sounds in environment by activation of the muscles

Question 80

desensitization, interference, injury protection theory

Answer 80

based on a review off existing theories of the nature of the ME muscle and reflex activity in human/animal species. desensitization: prevented ME muscle contractions elicited by eating, talking, yelling, and other vocalizations reduce the noises produced by those activities to reduce sensitivity and/or alertness to salient aspects of acoustic environment. Interference: prevented cuz the contractions reduce their masking of high freq. potential injury to hearing is avoided by the attenuation of intense sounds

Question 81

compare right and left ipsilateral and contralateral ways to probe

Answer 81

right ipsilateral and left contral = probe in R ear. right contra and left ipsi probe in LEFT ear