Hearing Screening: Audiometer Use, Care and Calibration

Hearing Screening Audiometer Use, Care and Calibration

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The Audiometer

MDH recommended audiometers have test tones ranging from 250 to 8000 Hz and volumes of 0-80/100 decibels, this allows the screener to perform both pure tone audiometry screening and threshold screening.

Headphones are calibrated to a specific audiometer and are not interchangeable with other machines.

MDH does not recommend speech stimuli screening equipment such as Verbal Auditory Screening for Children (VASC), where a word is presented to the child, and the child has to identify a related picture. Evidence indicates that the VASC is less effective than pure tone audiometry in identifying hearing loss.

Specifications vary somewhat between brands but most audiometers have the following dials:

  • Power or On/Off Switch: Needs to be on when screening.
  • Frequency Dial: The frequency dial rotates from 250 to 8000 Hz. This dial controls the test frequency or the pitch of the tone.
  • Decibel (dB) or Hearing Level Dial: This dial controls the test intensity or loudness of the tone. This is typically a rotary dial, which allows the screener to vary the tones presented in 5dB steps from approximately 0 to 80/100dB.
  • Tone Presentation Bar or Stimulus Switch: Pressing this bar presents the tone.

General Care

Handle gently and avoid dropping. When transporting the audiometer in a car, secure it so it will not fall during a sudden stop.

Avoid extreme temperatures (below freezing and above 90º F). Keep cords free of tangles and twists. Check all electrical connections, dials and switches for signs of problems. The headphone jacks should be removed from their plugs occasionally and wiped with an alcohol pad to improve the connection (Note: Do not use alcohol pads on the headphone ear pieces). Take proper care to prevent moisture from getting inside the audiometer.

Keep the case closed to prevent dust build-up. If the case or exposed surfaces become dirty, mild soap and water are usually sufficient to clean them.

Perform biological calibration and mechanical function checks each day, on each audiometer, before use.

Headphones

Clean headphones before each re-use with a cleaning agent or alcohol-free wipes. Do not use alcohol because it may dry out the rubber cushions on headphones. When the headphone cushions need cleaning, remove them from the headset, clean and dry thoroughly before replacing. Keep all moisture away from the diaphragm (the hole in the center of the headphones).

Audiometer Mechanical Function Check

Audiometer Mechanical Function Check (PDF) form.

Calibration

Audiometers should have yearly calibrations. Extensive calibrations are typically done at a repair facility or factory about every fifth year.

The Audiometer Needs Repair If:

  • Tone does not sound normal, static is heard, or sound is not produced when tone lever/button is pressed.
  • Headphones do not remain in proper position over ears.
  • A dial or switch does not function or indicator lights do not glow.

Biologic Calibration Check

(Optional unless performing threshold audiometry)

To ensure that the audiometer is ready for accurate screening, the person with primary responsibility for the hearing screening program should do biologic calibration checks. Perform this check prior to threshold screening or when there is reason to suspect the audiometer may not be working properly. Use procedure described below. Refer to the Biological Calibration Check Form (PDF).

Same Ear Hearing Level Procedure

  1. Obtain a threshold screening (refer to threshold screening section of this manual) on the better ear with the right (red) headphone and record the results.
  2. Obtain a threshold on the same ear with the left (blue) headphone and record the results.
  3. Check thresholds at each frequency to see that they differ by no more than ± 5dB. If they vary more than this, do not use the audiometer and have it checked by a technician.

Audiometer Supplies and Repair

Audiometer Repair or Purchase

Note: This resource list is for informational purposes only; the Minnesota Department of Health (MDH) does not endorse any particular product. In addition, MDH is not responsible for the content of websites listed here. Any person or entity that relies on any information obtained from this resources list does so at his or her own risk.

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