1. Summer 2007
SPA 4302
Pure Tone Audiometry

2. The Pure-Tone Audiometer
Electronic device that generates tones for determining _________________
Manufactured to specifications of the American National Standards Institute (ANSI)
Air/Bone Conduction
Testable frequencies (A/C): 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, 8000 Hz
Testable frequencies (B/C): ___ through _____ Hz
Masking control available

3. Test Environment
Background noise may affect audiometric results by __________ thresholds
Three ways room noise may be ___________
Earphone enclosure device
Insert earphones – foam tipped receivers that are inserted directly into the ears
______________________

4. The Patient’s Role
Patients must be aware that they are to indicate when they hear a tone
Patient response: hand raise, finger raise, signal button, vocal response, play
False responses
False negatives: patient _______________________ __________; misunderstood or forgotten instructions, feigning or exaggerating loss
False positives: patients responds when _______________________ – usually occurs when there are long silent periods in the test

5. The Clinician’s Role Convey task instructions to patient
Ensure understanding
Patient position
________________________________________________________________________________________

6. Air-Conduction Audiometry
Specifies ______________ at various frequencies
Can’t tell whether deficit is conductive or sensorineural, or mixed
Earphone placed with diaphragm aimed directly over ____________
Be careful of canals that collapse due to the pressure of the earphones – use ______________ if this is a potential problem

7. Air-Conduction Audiometry
Test the known or suspected ___________ first
Begin at 1000 Hz – easily heard by most and high test-retest reliability
ORDER of FREQS: 1000, 2000, 4000, 8000,
recheck of 1000, 500, then 250
Test at the octave points and the mid-octaves (750, 1500, 3000, 6000 Hz) if there is a difference of 20 dB or more between adjacent octaves

8. Measuring a Threshold at Each Freq.
Start presenting pure tones at ________ HL
No response? Raise the level to 50 dB HL
Still no response? Raise the level in 10 dB increments
Whenever person responds, _____________ dB
Whenever no response, ________________ dB
Threshold=the lowest level at which the patient can correctly identify the tone presentation at least 50% of the time, with a minimum of 3 responses at a given level.

9. Air-Conduction Audiometry
The Audiogram
Frequency (in hertz) on the x-axis, Intensity (in dB HL) on the y-axis
Moving left to right, frequency increases; moving top to bottom, intensity increases
Symbols are placed to correspond to threshold at a given frequency:
Air conduction
Bone conduction
Air—Masked
Bone—Masked
Right O
< [
Left X
> ]

10. The Audiogram Thresholds by frequency
Hearing by air and bone transmission

11. Severity of Hearing Loss

12. Air-Conduction Audiometry
Pure-tone average (PTA)=average of air conduction thresholds obtained at ___, _____, and _____ Hz in one ear
Useful for predicting threshold for speech
Percentage of Hearing Impairment
Ignores audiometric configuration and looks only at average hearing loss
Often confusing and misleading to patients

13. Air-Conduction Audiometry
PTA (dB)
Degree of Communication Impact
0-15
None
16-25
Slight
26-40
_______
41-55
Moderate
56-70
Moderately Severe
71-90
______
> 91
Profound

14. Bone-Conduction Audiometry
3 Mechanisms of Bone Conduction
_______________ Bone Conduction
____________ Bone Conduction
______________ Bone Conduction
Bone Oscillator Placement
___________,
or, _________

15. Bone-Conduction Audiometry
Occlusion Effect
When the ears of patients with normal hearing or SNHL are covered or occluded, there is an _________ in intensity of sound delivered via a bone oscillator
Affects ________ Hz and below
Result of increase in SPL in the ear canal when the outer ear is covered
Markedly decreased when insert phones are used (as opposed to supra-aural headphones)

16. Bone-Conduction Audiometry
No matter where the oscillator is placed, you can never be sure which cochlea is being stimulated! (more on this to come)
Frequencies usually tested:
250, 500, 1000, 2000, and 4000 Hz
Symbols for bone conduction are only connected on the audiogram (with dashed lines) when there is a __________ or __________ loss.

17. Audiogram Interpretation
Look at:
hearing sensitivity by AC
hearing sensitivity by BC
AC/BC difference (a.k.a. the air-bone gap)
No air-bone gap = ________________
AC worse than BC = ______________ hearing loss
Watchout: low frequencies at high levels via BC can be perceived as a __________ signal!

18. Another Thing to Watch Out For:
Cross Hearing: sound delivered to one ear but perceived in the other ear.
Interaural Attenuation (IA)—How much sound it takes to reach the other side:
Air conduction IA = __ dB
Bone conduction IA = __ dB
Danger for cross-hearing
For AC—If AC threshold in the test ear, minus IA, is greater than or equal to the BC threshold of the opposite ear
For BC—If Air-bone gap of test ear exceeds ___ dB
Insert Phones >60 dB

19. Masking
Masking—keeping the non-test ear “busy” in order to ensure that it is actually the test ear which is responding
Noises used to mask:
____________—has approximately equal energy per cycle & covers a broad range of frequencies
_____________—made up of frequencies that immediately surround the pure tone being tested
Insert earphones recommended because:
They lessen the ____________
They provide much more __________________

20. Effective Masking: Calibration of the noise
dB EM (Effective Masking) describes the level to which a threshold will shift in the presence of a given level of noise
So, 45 dB EM should raise the threshold for a tone to 45 dB HL in the ear in which both are presented.

21. Masking Masking for air conduction Masking for bone conduction
“Shotgun” Approach
Minimum-noise method
Maximum-noise method
____________ method
Masking for bone conduction
Similar to air conduction
Beware of _____________, and ___________

22. Computerized Audiometry
Using a device remotely operated by a computer and data is stored
Computer can control all aspects of testing and masking and analyze patient responses
Used more often for __________, ___________, and ____________ applications (large number of people to test)