An image of a hearing health care provider reviewing an audiogram generated by SHOEBOX Audiometry with her patient

Daily Maintenance and Calibration Requirements for Audiometers Used in Occupational Hearing Testing

Hearing Conservation, Hearing Conservation eBook

There have never been better audiometer options for occupational hearing testing than what’s available now. Despite the advances in technology, there are still quick verification tasks that will help ensure that your testing equipment is performing the way it should every day of testing. Modern audiometers and headsets often offer interesting features to allow for daily verification tasks, routine maintenance, and associated record-keeping. In this chapter, we will be reviewing each of those tasks to help illustrate what maintenance you need to perform to help you meet OSHA hearing testing compliance.

Annual Calibration

All hearing testing systems should be calibrated at least once every 12 months. Historically, audiometers often remained stationary and were calibrated by a technician who visited the site where the OSHA-compliant audiometer was being used and provided a calibration report and associated correction factors. With advancements in technology, both in audiometer capabilities and the improvement in robustness in hardware components in audiometric headsets, calibration can look a little different than in years past. For computerized and tablet-based audiometers, a full calibration can be obtained by testing the headset alone and providing calibration correction factors. These calculations are then applied to the software resulting in a re-calibrated system.

ANSI/ASA S3.6 specifies that all clinical audiometers need to be calibrated at a minimum every 12 months. OSHA 29 CFR 1910.95 differentiates between periodic and exhaustive calibrations; however, once a system or headset is on-hand for calibration, most calibrators will opt for an exhaustive calibration, which in turn meets the ANSI specifications as well as the ones specified by OSHA.

Daily Functional Check

The purpose of the Daily Functional Check is to ensure that the cable connections are interruption-free and that there is no abnormality (static, volume changes) in the sound output of the testing system. For this test, ANSI recommends using a 1000 Hz tone at 70 dB(HL) and requests that the test administrator put on the headphones and present these tones one at a time in each ear, all while putting slight pressure on the headphone jack connectors, and wiggling the cables to listen for any abnormalities. The tone presentation time should be approximately 20 seconds on each ear to allow for adequate manipulation of the jacks and cables. Should abnormalities be discovered, these should be addressed prior to continuing with testing. The Daily Functional Check is a static one-time verification each testing day, and the results should be recorded to help with the possible future investigation of an emerging equipment issue or in the case of an audit request for
equipment verification practices.

Daily Biological Verification

The Biological Verification aims to ensure that there hasn’t been significant sound output drift on a per-frequency basis since the last annual calibration. In order to set up this test, it is recommended that you create a distinct result file for this purpose for each individual who may administer workplace hearing testing. For example, creating a file with the patient name ‘Biological Verification A.A.’ under which every test can be saved and compared to baseline. Only individuals with stable hearing levels should perform Biological Verification.

After the first test for an individual has been marked as a ‘baseline,’ each test after that can be compared frequency-by-frequency for deviations of more than 10 dB(HL). Should there be deviations of more than 10 dB(HL), the system will require additional attention, and we would recommend contacting your Professional Supervisor or Hearing Conservation Program Administrator for recommended next steps.

Baseline test results

Everyday Troubleshooting

You may want to add additional verification measures if you notice wear and tear on the device or headphones. For example, a tear or fraying with any portion of the headphones. It’s possible for the headband or adjustment stems of the headphones to become warped or loose. If the headband is loose, you can apply gentle pressure on both sides to reshape the curvature of the band. Should corrosion or deposits be noted on the headphone jack (it could be green, black, or clear in colour), cleaning the jack with an alcohol wipe and allowing it to dry before plugging it back in is recommended.
It goes without saying that if a system is dropped, exposed to extreme temperature fluctuations, or compromised in any other significant fashion, all components should be reverified in the manners described above. In abiding by these practices, you can be fully confident that your audiometric system is providing accurate hearing testing results throughout the whole year through.