Exam 3

type

type

refers to what we call the “site of lesion”. Where in the auditory system hearing loss is located

degree

refers to the severity of the hearing loss. We can use a dB value an adjective descriptor, or both

configuration

refers to the shape and slope of the pure tone air conduction results across the frequencies tested

to determine the type of hearing loss we compare

air conduction and bone conduction

conductive

outer and middle ear - acts to conduct or transfer the sound to the cochlea

sensorineural

inner ear (IE) and 8th nerve - IE= sensory problem with the 8th nerve = neural problem

normal hearing

there is no loss of hearing; air and bone conduction are all within normal limits and the same level

conductive hearing loss

there is a loss by air conduction, with normal bone conduction thresholds

conductive loss

the sound is attenuated or decreased as it travels through the outer or middle ear. It reaches the cochlea at the reduced level

air-bone-gap

the difference between air conduction and bone conduction thresholds are 15 dB or greater

sensorineural hearing loss

there is a loss by air conduction when sound reaches the inner ear it is decreased

sensorineural

there is a loss by air and bone conduction - we are not testing the inner ear directly, and this is the location of damage, there will be an equal loss

most sensorineural hearing losses are

permanent

mixed hearing loss

there is a loss by air conduction, bone conduction, and an ABG

pure tone average

the average of the air conduction thresholds at 500, 1000, 2000 hz

if there is a 20 dB or higher gap between the 3 frequencies we

only test the better 2 frequencies

-10 - 20

normal

21 - 40

mild

41 - 55

moderate

56 - 70

moderately-severe

71 - 90

severe

above 90

profound

most common type of configuration

high frequency slope

5 - 10 dB per octave

gradual

15 - 20 dB per octave

sharp

25 dB per octave

precipitous

<5 - 10 difference across audiometric thresholds

flat loss

low frequency loss

this is where the hearing loss is confined primarily to low frequencies or greater at the lows than the highs

u-shaped, trough, cookie bite

greater hearing loss in the mid-frequencies of the audiogram

saucer shaped

better hearing in the mid frequencies and poorer hearing in the low and high frequencies

notched

there is a dip on one region or the audiogram with significantly better or normal hearing at surrounding frequencies

bilateral

both ears

unilateral

one ear

symmertrical

same or similar

asymmestrical

dissimilar

threshold

a minimum value which will evoke a sensation (least amount of intensity needed)

auditory threshold (ANSI)

the minimum effective SPL of an acoustic signal producing an auditory sensation in a specified fraction of trials

value we use for threshold

50%

auditory factors

affect threshold; environment, stimulus, or equipment

duration of the signal

1-2 seconds at best (3-4 beeps)

auditory facts that affect threshold

duration of the signal, continuous vs interrupted, noise level in the room, calibration of equipment, earphone placement or insertion

non-auditory factors

not related to acoustic parameters (more related to person or tester)

non-auditory factors that affect threshold

instructions, psychological/physical state of the patient, threshold criterion, reinforcement, attenuation step size, patients ability to complete the task, timing pattern during presentation of stimuli

listening check

this is also referred to as a “biological check”. Always complete this as an initial step after the audiometer has been turned on

otoscopic examination

to check mainly for visible external ear abnormalities (cerumen or other debris) and a gross evaluation of the TM. Also check for collapsed ear canals

7 years

on average people wait _________ when they think they have a hearing loss before going to an audiologist

instructions to the patient

instruct the patient prior to placing earphones on or in the ears (talk before you test)

make sure instructions are:

simple, easy to understand, age apporpiate, talk before you test

directions need to be

brief, uncomplicated, and language appropriate ea

earphone placement

you may want to ask the patient to remove glasses or earrings (depends on what type of transducer is being used). Make sure to ask them to remove GUM

when using supra-aural earphones

place supra-aural earphones on the patient while standing in front of them. Remember when you do this your right is their left and vice-versa. Place diaphragm over the opening of the ear canal

when using insert earphones

they will be inserted while standing beside the patient and observing placement

advantages of insert earphones

greater reduction in ambient noise, improved test-retest, reduction of ear canal collapse, reduced need for masking

ear selection

always test the better ear first, or the presumed better year. If the patient doesn’t feel one ear is better than the other, test the right ear first

obtaining threshold

ASHA proposed the procedure and it is based on the initial work of Hughson and Westlake and then modified by Carhart and Jerger

you start testing at

1000 Hz

familiarization

begin at 30 dB HL

up 5 down 10

decrease the intensity level of the signal by 10 dB HL after the patient gives a correct response. increase the intensity level in 5 dB HL steps if the patient fails to respond

use to determine patient clinical threshold

the lowest dB HL at which the patient responds at least 50% of the time, with the minimum of two responses at that level. minimum of two times at an intensity

false positive

most common, patient responds when no signal has been presented of the stimulus is below threshold, even reliable and consistent patients may give some false positive responses

false positives could be caused by

tinnitus, physiological noise, rhythm patterning

false negatives

the failure of a patient to respond during a hearing test when he or she has in fact heard the stimulus

false negatives may result from

those attempting to exaggerate a hearing loss, poor instructions

frequencies that are tests

250, 500, 1000, 2000, 4000, 8000

exception to tested frequencies

if there is a 20 dB or greater difference between adjacent octaves then test interoctaves

frequency testing order

1000, 2000, 4000, 8000, 500, 250

air conduction testing

test sounds as it passes through the outer, middle, and inner ear. Results can tell you the degree of hearing loss but can’t tell you where the problem is.

bone conduction testing

directly measures the sensitivity of the inner ear (cochlea). This information is critical to determine the site in the auditory system where the hearing loss is.

during bone conduction the

bones of the skull vibrate which causes the fluids in the inner ear to be set in motion and causes the traveling wave and basilar membrane displacement

what type of transducer does bone conduction use

bone conduction oscillator (vibrator)

the oscillator gets placed on the

mastoid process

steps of placing the oscillator

remove hair from the surface, put the side of the raised round disk against the head, be sure the oscillator doesn’t slide back, be sure the oscillator doesn’t touch the pinna, put the band over the patients head

two places the oscillator can be placed

mastoid process and the forehead

placing the oscillator on the forehead

gives more reliable results, bone surface on the forehead is more homogenous, reduced participating of the middle ear

biggest disadvantage of placing the oscillator on the forehead

you will need more intensity to reach threshold

bone conduction threshold

50 % rule, same ascending technique as air conduction

bone conduction testing frequencies

250, 500, 1000, 2000, 4000

why do we not test above 4000 Hz

it takes a lot more energy to reach threshold by bone conduction than air conduction

the output level for bone conduction at 250 Hz could be

as low as 40 dB

the output level for bone conduction at 1000, 2000, 4000 Hz are

60-80 Hz

masking

refers to the elevation in threshold of one sound by the presence of another sound, called the masker

ipsilateral masking

tone and masker presented to same ear

contralateral or clinical masking

tone and masker presented to opposite ears

why do we mask

to guarantee that the response from the patient is accurate and a valid representation of the hearing sensitivity for the ear being tested

tests that masking can be completed

air conduction, bone conduction (most common), speech audiometry

narrow-band noise

used for AC and BC, 1/3-octave wide

speech noise

used for speech audiometry, broad band spectrum which is more representative of the speech frequencies

<

BC right ear unmasked

[

BC right ear masked

BC left ear unmasked

]

BC left ear masked

o

AC right ear unmasked

x

AC left ear unmasked

triangle

AC right ear masked

square

AC left ear masked

S

sound field

A

aided sound field

upside down V

unspecified BC

hearing screening

the presumptive identification of unrecognized disease or defect by the application of tests, examinations, or other procedures which can be applied rapidly (normal hearing or hearing loss)

a screening test is not meant to be

diagnostic