Pure Tone Audiometry Flashcards
What are the parts of the pure tone audiometer?
- power: on/off
- test type
- stimulus
- transducer
- frequency selector dial
- attenuator
- interrupter
What is the principle objective of pure tone audiometry?
to determine the sensitivity of the human auditory system
What is reliability?
is the test repeatable?
what is validity?
does the test measure what it is supposed to measure?
What are the four ways the test could turn out?
- true positive
- true negative
- false positive
- false negative
What does the Clinical Decision Analysis (CDA) do?
it asks questions about each test’s sensitivity, specificity, efficiency, and predictive value
What is the Clinician’s Role in Pure Tone Audiometry?
- provide clear instructions
1. tell client purpose of test
2. tell client what they will hear
3. tell client what to do when they hear the stimulus
4. tell them to stop doing whatever behavior you requested in step 3 when tone goes away - perform test accurately
What is the patient’s role in manual pure tone audiometry?
yield a behavioral response to the acoustic stimulus; raise hand, drop toy in bucket, etc.
What is a Threshold?
the lowest signal intensity at which multiple presentations are detected 50% of the time
What are the extrinsic factors that affect pure tune threshold variability?
things in the physical environment: temperature, lights, ambient noise
What are the intrinsic factors that affect pure tone threshold variability?
neurophysiological factors and subject motivation
What is ASHA’s 1978 procedure?
- Begin at 1000 Hz in the right ear, or the better ear
- Present tone at 30 dB HL. If no response is obtained, raise to 50 dB HL
- If there is no response, continue to raise the stimulus in 10 dB steps until a response is obtained or until the limit of the audiometer is reached
- after a response is obtained, lower the level of the tone in 10 dB steps
- each time a tone is introduced, it is maintained for one or two seconds
- all ascending movements of the hearing level dial from this point on are made in 5 dB steps
- When a tone is lowered below the patients response level, it is then raised in 5 dB steps until it is audible again, then lowered in 10 dB steps and raised in 5 dB steps until the 50% threshold response criterion has been met
What is an Audiogram?
a chart or graph that shows the hearing level on the ordinate lines and the frequency of the stimulus tone on the abscissa
Red Circle
right ear, unmasked, AC
Red Triangle
right ear, masked, AC
Blue X
left ear, unmasked, AC
Blue Square
left ear, masked, AC
Red
right ear, unmasked, BC
Red [
right ear, masked, BC
Blue >
left ear, unmasked BC
Blue ]
left ear, masked BC
Blue S
sound field
Blue A (underlined twice)
aided responses
Red O with arrow
air conduction responses for the right ear not observed at the limits of the audiometer
Blue CI
responses with a cochlear implant
PTA: -10 to 15
None/ Within Normal Limits
PTA: 16-25
Slight
PTA: 26-40
Mild
PTA: 41-55
Moderate
PTA: 56-70
Moderately severe
PTA: 71-90
Severe
PTA: > 91
Profound
What is the Pure Tone Average?
average threshold levels at 500, 1000, and 2000 Hz
What is Fletcher’s Average (FA)
the better (lowest) two threshold levels between 500, 1000, and 2000 Hz
What is the Variable pure tone average (VPTA)?
the poorest of the three threshold levels between 500, 1000, 2000, and 4000 Hz
What does bone conduction arise from?
interaction of at least 3 different phenomena:
- distortional bone conduction
- inertial bone conduction
- osseotympanic
What is the primary compliant in conductive hearing loss?
decrease in the strength of sound
Anatomically, which structures are involved in Conductive Hearing Loss?
- pinna
- EAC
- TM
- ossicular chair
- Eustachian tube
Audiometrically, what do we look for in conductive hearing loss?
- the amount of hearing loss by AC
- the amount of hearing loss by BC
- the relationship between AC and BC
With CHL, AC will be ____ and BC will be ____
AC: abnormal
BC: normal
True or False: there will be an air bone gap (ABG) in CHL
True
What is an Air Bone Gap?
the difference between the AC and the BC; it will be 10 dB or more
What does the ABG show?
the amount of the conductive involvement
What is the complaint from a client with sensorineural hearing loss?
trouble hearing and difficulty understanding speech even in quiet
Anatomically, which structures are involved in sensorineural hearing loss?
usually problems occur in the cochlea, but it could be in the temporal lobe, brain, etc.
Audiometrically, what do we look for in sensorineural hearing loss?
AC will be abnormal
BC will be abnormal
AC and BC will be near equal, interweaving with no significant ABG
What is mixed hearing loss?
a problem occurring simultaneously in both the conductive and sensorineural mechanism
Anatomically, which structures are involved in mixed hearing loss?
peripheral auditory system
What is the first line of business to take care of in a patient with mixed hearing loss?
to get rid of whatever the blockage is to get rid of the conductive problem, then retest
Audiometrically, what do we look for in mixed hearing loss?
AC will be abnormal
BC will be abnormal
AC and BC will be separated by 10 dB or more
there will be at least a 10 dB ABG
What is interaural attenuation?
the amount of sound that is attenuated or reduced when crossing from one ear to the other; how much the human skull can absorb before sound crosses over to the other ear
What does masking depend on?
- frequency
- the patient, depending on the thickness of the skulls
- the transducer used (earbuds, headphones, BC oscillator)
What is crossover?
actual amount of dB that can leave the ear you’re testing that can crossover through brain to other ear’s cochlea
What is contralateral Masking?
introduce stimulus to non-test ear while establishing threshold in the test ear
When do you mask for AC?
the danger for crossover for AC tones present itself whenever the level of the tone in the TE by AC, minus IA is equal to or higher than the BC threshold of the NTE
What should we use for IA for AC?
40 dB
What should we use for IA for BC?
10 db
What do you mask for BC?
when the ABG in the Test Ear is more than 10 dB
What are the types of maskers?
- white noise aka thermal and Gaussian noise
- wide band or broad band noise
- complex noise
- narrow band noise
- speech noise
What are the three questions for effective application of clinical masking?
- when should masking be used?
- What kind of masking noise should be used?
- how much making should be used?
When should making be used?
AC: when you exceed threshold in good ear by 40 dB or more
What kind of making noise should be used?
should always be narrow band noise
how much masking should be used?
depends on the threshold
What is the Plateau Method?
- when a tone seems to be heard thru the NTE, a noise is delivered to that ear and the level of the noise is increased in 5 dB steps until the tone is no longer audible
- increase masking noise in 5 dB steps three consecutive times without causing shift in threshold in the TE- this is the plateau
- has to be a 15 dB plateau where person can still hear the noise in the testing ear
What is Rule #1 for masking?
Pure tone air-conduction audiometry
(a) when the AC threshold of the TE and the AC threshold of the NTE differ by IA (40 dB) or more, use masking. cross over may have occurred
(b) when the AC threshold of the TE and the BC threshold of the NTE differ by IA or more, using masking
What is Rule #2 for masking?
Pure tone bone conduction audiometry
- when the AC threshold of the TE and the BC threshold of that same ear differ by more than 10 dB, use masking
