Ch. 7: Audiometric Technique

Question 1

Briefly summarize the information obtained in a case history. (8)

Answer 1

1. Personal data of the worker (for record keeping)
2. Noise-exposure history pertaining to previous work
3. Noise exposure at the current job
4. Noise exposure off the job
5. Worker’s use of hearing protection
6. History of ear disorder(s)
7. History of problems that could point to a hearing problem
8. Worker’s perception of his or her hearing

Question 2

Why is a case history useful?

Answer 2

• The case history is a useful record for the technician when explaining audiometric results and educating a worker.
• The history may indicate to the technician what to expect in terms of test results. It will often indicate which ear to test first when performing audiometry.
• The case history can also supply useful information for an audiologist or doctor if referral is necessary.
• A history is also useful if a worker submits a claim for compensation because the WCB often requests worker records.

Question 3

How would you ensure that the worker understands the test instructions?

Answer 3

• Giving instructions simply and briefly helps to ensure the worker understands.
• Ask the worker if they understand the instructions.

Question 4

What equipment and supplies are required for an audiometric test? (7)

Answer 4

1. an audiometer with earphones or ear inserts
2. an audiometer daily check record form
3. a worker’s audiometric record form
4. an otoscope
5. disposable tips for the otoscope
6. a red pen
7. a blue pen

Question 5

What steps are involved in preparing the equipment for an audiometric test?

Answer 5

1. Ensure the audiometer has been calibrated within the last year.
2. Plug audiometer into a wall outlet.
3. Ensure that the earphone cords are plugged into the machine correctly (the red [right] earphone into the outlet marked red, and the blue [left] earphone into the outlet marked blue).
4. Turn the machine on. If the right ear is to be checked first, set the audiometer to the right ear.
5. Allow machine to warm up for at least five minutes.
6. Attach a disposable tip to the otoscope.
7. Make sure the otoscope emits enough light to examine the ears (shine the light on your palm).

Question 6

What steps are involved in the daily equipment check?

Answer 6

-Should be completed before using the equipment to perform a hearing test. If used less frequently than daily, these full tests should be performed prior to use.
-These should be performed weekly in full, and daily for subjective calibration test.
1. Clean and examine the audiometer and accessories. Check plugs, main leads, and accessory leads for signs of wear or damage.
2. Ensure that all switch knobs are secure and indicators function correctly.
3. Ensure that the client signal system (response switch) operates correctly.
4. Check tension of headset headband. Ensure swivel joints are free to turn without being excessively slack.
5. Switch equipment on and leave for recommended warm-up time (5 minutes or as per manufacturer’s specifications). Carry out any setting-up adjustments as specified by the manufacturer. On battery- powered equipment, ensure the battery state by specified method. Ensure the earphone serial numbers correspond with the instrument.
6. On automatic recording audiometers, check the marking pen and mechanical operation and function of limit switches and frequency switches. Ensure that no extraneous instrument noise is audible at the subject position.
7. Check through at a high level (60 dB) at all frequencies used, for both earphones; listen for proper functioning, absence of distortion, freedom from interrupter clicks, etc. Check earphones, plugs, and leads for intermittency.
8. Compare the current hearing threshold levels of one otologically normal subject (may be the technician) with his/her previously recorded baseline audiogram (biological check) If it does not differ by more than +/- 5 dB at all frequencies, the audiometer may be considered satisfactory for use. If it differs by more than +/- 5 dB, the hearing levels of a second otologically normal subject should also be compared to his/her previously recorded baseline audio. If this also indicates a difference greater than +/-5 dB, the audiometer shall be referred for objective calibration tests and recalibrated as necessary.
i. Listen at low levels for any:
i) Signs of noise or hum or other unwanted sounds; and
ii) Change in tonal quality.
j. Ensure that the attenuator(s) does attenuate over the full range
i) Set the frequency at 4000 Hz and present tones starting at 60 dB
and decreasing to 0 dB. Ensure that the tone is heard over this entire range. Check each test frequency in the right and left ear from 500–8000 Hz.
k. Ensure that the interrupter keys operate silently and that no noise radiating from the instrument is audible at the subject’s position.
-The daily biological check can also be completed using an electronic device called a bioacoustics simulator. If using the simulator, the earphones are placed on the instrument and the technician completes the test. In a microprocessor audiometer, the biological test may run automatically.
-The equipment is now ready for performing a hearing test.

Question 7

What are the reasons for examining the ears with an otoscope?

Answer 7

• The technician examines the ears for screening purposes. If a worker has noticed a sudden change in his or her hearing level, it may be due to impacted wax. An ear examination will indicate the presence of wax in the ear canal.
• Follow your company’s policy regarding what action to take when workers have excessive wax. In general, you should proceed with the test.

Question 8

What are the steps involved in examining the ear with an otoscope?

Answer 8

• In addition to obtaining a history, the technician should look at the worker’s ears and into the ear canals to check for wax buildup that may affect the hearing test results.
• If there are any obvious conditions identified during visual examination of the external ear, the worker should be referred to a physician.
• An otoscope is a hand-held instrument with a light that illuminates the ear canal.
  1. Look at outer ear for any redness/irritation.
  2. Turn the otoscope on.
  3. Gently grasp the upper part of the outer ear.
  4. Gently pull the outer ear up and back. With the light view the ear canal to check for wax.
  5. Gently insert the otoscope into the ear canal. Look through the otoscope and observe the ear canal for the presence of wax.
  6. Repeat for the other ear.
  7. Turn off the otoscope.
  8. Discard the disposable tip.

Question 9

What steps are involved in conducting an audiometric test?

Answer 9

The steps involved in conducting an audiometric test are as follows:
a. Set audiometer for left or right (start with better ear.)
b. Set intensity at 40 dB and frequency at 1000 Hz.
c. Present tone by depressing stimulus button.
d. Look for worker’s response indicating whether they heard the tone. If no response, increase intensity by 10 dB increments, present tone, and continue until worker responds.
e. After worker’s response, decrease dB level by 10 dB.
f. Present tone.
g. Look for worker’s response.
i) When there is a response, decrease dB level by 10, present tone, and continue to decrease by 10 dB increments until no response.
ii) When there is no response, increase the dB level by 5, present the tone, and continue to increase by 5 until there is a response. Mentally record this threshold.
h. Repeat steps g.(i) and g.(ii) until two out of three responses (or three out of five responses) occur at the same dB level. Record this result on the audiogram form.
This is the ascending–descending technique used throughout the test to establish thresholds at each frequency.
Down by 10s — Up by 5s
i. Continue testing by repeating steps c. through h. at each frequency in the following order: 2000, 3000, 4000, 6000, and 8000 Hz. Record result for each threshold on audiogram form.
j. Recheck the first threshold you established at 1000 Hz by repeating steps b. through h.
i) If the recheck threshold is within 5 dB of the first recorded threshold, record the second response and go to step m.
ii) If the recheck threshold is not within 5 dB of the first recorded response, re-instruct the worker, then repeat steps b. through i.
k. Finish testing the ear at 500 Hz.
l. Set audiometer to the opposite ear.
m. Repeat all steps for other ear.

Question 10

For what reasons would the technician postpone the test? (6)

Answer 10

You may have to postpone a test if any of these conditions apply:

a. problems are detected with the audiometer while performing the daily check and another audiometer is not available
b. your audiometer has not been calibrated by a laboratory within the last year
c. a worker has ear, nose, or throat problems and cannot undergo audiometry
d. a worker has been exposed to excessive noise within the last 12–14 hours without hearing protection
e. test environment is too noisy
f. you cannot establish thresholds

Question 11

List some testing tips for hard-to-test employees.

Answer 11

a. if using a microprocessor audiometer, try using manual mode.
b. If employees have tinnitus and are known to be difficult to test, do manual testing.
c. Avoid leaving an employee in the test booth for periods longer than 10 minutes. Provide a small break.
d. Explain to workers that wear hearing aids that the hearing aids must be removed to do audiometric testing. Share their results in a positive way.
e. Prevent negative experiences during testing. Try to understand the worker’s perspective of the audiometric experience.

Question 12

Audiometry Procedure Checklist: (10)

Answer 12

1. Gather equipment and supplies.
2. Prepare equipment for testing.
3. Perform daily equipment check.
4. Obtain the worker’s history.
5. Examine ears with an otoscope.
6. Position the worker for the test.
7. Instruct the worker.
8. Conduct the audiometric test.
9. Record the worker’s thresholds.
10. Record the test’s reliability.