Pure Tone Audiometry Flashcards
why do we test hearing using pure tones?
- frequency specific thresholds
- type and severity of hearing loss
standard earphones
- proper placement is quick and easy
- easier and more comfortable for children
- inexpensive
insert earphones
- proper placement can be tricky
- children may not participate with fitting due to discomfort
- expensive
- better at reducing ambient noise during testing outside of a sound booth
air conduction audiometry
assessing the air conduction pathway which is how we hear normally
outer ear - middle ear - inner ear
threshold
the lowest decibel (dB) hearing level in which a person can hear a signal and respond
right ear air conduction symbol
O
left ear air conduction symbol
X
no response air conduction symbol
arrow attached to a symbol
ex: X with arrow
air conduction audiometry, methodology
- 250, 500, 1000, 2000, 4000, 8000 Hz
- begin in the right ear first (or better ear) at 30 dB and 1000 Hz
- followed by 2000, 4000, 8000 Hz
- repeat 1000 Hz
- then 500 and finally 250 Hz
air conduction methodology: no response?
continue in 10 dB steps until response
air conduction methodology: no response at starting level of 30 dB?
begin at 50 dB
when searching for threshold, you will use…
bracketing
- 10 down, 5 up
- consistent response 3 times at lowest intensity, that is threshold
degree of hearing loss: normal
-10-25 dB
degree of hearing loss: mild
26-40 dB
degree of hearing loss: moderate
41-55 dB
degree of hearing loss: moderately-severe
56-70 dB
degree of hearing loss: profound
91 dB and above
bone conduction hearing
we can bypass the outer and middle ear by stimulating the inner ear through vibration of the skull
components of bone conduction
- distortional
- inertial
- osseotympanic
distortional bone conduction
distortion of the skull activates structures of the inner ear
inertial bone conduction
distortion of the skull causes the ossicular chain to move and it lags behind skull movement due to inertia
osseotympanic bone conduction
distortion causes air to vibrate in the ear canal, some sound waves exit ear canal while others continue back the air conduction pathway
bone conduction methodology
frequencies 500, 1000, 2000, 4000 Hz
why do we not test the same frequencies for bone conduction?
sometimes 250 Hz can be affected by ambient noise and oscillator cannot vibrate over 4000 Hz
bone conduction: intensity limit
70-75 dB
why do we test different intensities for bone conduction?
cannot test above 75 dB since the person will feel it before they hear it
bone conduction right ear symbol
<
bone conduction left ear symbol
>
is bone conduction testing before or after air conduction testing?
after
bone conduction methodology: placement
directly on the mastoid area behind right or left ear
why doesn’t it matter which side to place the bone oscillator?
- the better cochlea will always respond to the tone first
- can’t vibrate half of your skull
why do we test both air and bone?
to determine the location of the hearing loss
SLPs will likely never perform masking, however, it is important to know how…
to interpret an audiogram that has masked thresholds
when is masking used?
- during air conduction testing when one ear is significantly better than the other ear at specific frequencies
- during bone conduction to isolate a cochlea
cross hearing
when the signal presented to the poorer ear is so loud that it “crosses over” to the better ear and that ear responds
shadow curve
responses on an audiogram are falsely recorded because the good ear is the ear that actually responded to the stimulus
masked right ear air conduction
triangle
masked left ear air conduction
square
masked right ear bone conduction
[
masked left ear bone conducion
]
if you see an audiogram that has the masking symbols, it means that…
the tester used masking and the results are accurate
what is masking?
- presenting “noise” to the good ear to keep it “busy” and raise its threshold so that it cannot “help” the bad ear
- the better ear will have a continuous narrow band noise, while the poorer ear is being presented with the pure tones (or other stimulus)
how do we know when to mask?
- based on interaural attenuation
- rule of thumb for air conduction masking
masking: based on interaural attention
difference in decibels, between the intensity of sound that was presented to the poorer ear and the amount of sound that actually reached the good ear
masking: rule of thumb for air conduction masking
- if at a specific frequency there is a 40 dB or more difference between the right ear and the left ear
- this is frequency specific, you have to look at each frequency separately
sound field testing
testing in the sound booth through speakers (can’t test ears individually)
sound field testing: used for…
- specialized tests for young children; most will not tolerate wearing headphones of any kind
- hearing aid functional gain testing
visual reinforcement audiometry (VRA)
- conditioned orientation reflex (COR) and tangible reinforcement operant conditioned audiometry (TROCA)
- uses the sound field
- signal is presented through either a right or left mounted speaker
when the child looks toward the correct speaker, they are visually rewarded…
- a box that lights up with a dancing animal
- a computer screen with a cartoon
behavioral observation audiometry (BOA)
- subjective test for children with a developmental age of up to 6-7 months
- behavioral technique
- typically reflexive responses
- uses noisemakers, warble tones, music, etc.
reflexive responses
- eye blinks, startle response
- changes in sucking behavior or breathing
conditioned play audiometry (CPA)
- for children 2 1/2 to 5 years of age
- condition time to respond to a stimulus through play (ring on peg, block in bucket, tec.)
- can be done with headphones
false negative response
- patient forgets to raise hand
- patient is exaggerating a hearing loss
- reinstruct
