Highlights of Noteworthy Decisions

Decision 401 20
06/05/2020
K. Jepson
  • Hearing loss
  • Medical opinion (hearing loss) (testing procedures)
  • Medical report (Tribunal medical discussion paper)

The worker appealed a decision of the Appeals Resolution Officer denying entitlement for noise-induced hearing loss in 2015.

There were audiograms from 2015 and 2016. The difference in the overall hearing loss measured in the 2015 audiogram and 2016 audiograms was very significant. The Vice-Chair found that the 2016 test was a much more reliable test result than the 2015 audiogram. With the 2015 test, there were no summary comments or other indicators that the reliability of the results were specifically considered and assessed. This was particularly significant given that there were aspects of the test results which suggested possible reliability issues. With the 2016 test, there was an indication that the audiologist specifically assessed reliability measures and found good reliability.
One key respect in which the 2016 audiological testing differs from the 2015 testing is that the 2016 testing included evoked potential (EP) testing. The Tribunal's medical discussion paper on hearing loss discusses some of the audiometric testing procedures, including threshold evoked potential testing. Evoked potential testing directly measures cortical response to sound stimuli. Because it does not depend on any voluntary response by the patient, EP testing can help establish with greater reliability the portion of any hearing loss that is purely sensorineural.
The discussion paper also explains that comparing speech recognition threshold (SRT) values averaged at 500, 1000, and 2000 Hz with the pure tone values averaged across those three frequencies should yield roughly equal results. If there is a significant discrepancy, this could imply an exaggerated hearing loss as well. In the 2015 audiogram the SRT values and pure tone values averaged at the stated frequencies did not yield roughly equal results.
The 2016 test included both air conduction and bone conduction values. The air conduction values met the Board policy threshold for entitlement but the bone conduction values did not meet the threshold. Further, EP values showed even less hearing loss. Since the worker does not meet the threshold on either EP or bone conduction values, it was unnecessary in this case to determine how the EP values would be factored into the calculation.
The Board has a practice of using bone conduction values to make the determination of the degree of loss, but that practice has never been incorporated into its formal published NIHL policy.
The Vice-Chair referred to and followed his reasoning in Decision No. 1052/17. Since NIHL is a sensorineural loss and bone conduction isolates the component of the loss that is purely sensorineural, bone conduction testing provides a better measure of NIHL. Air conduction values measure the overall hearing loss which includes both a conductive and a sensorineural hearing loss. As a conductive hearing loss would not be due to NIHL, bone conduction values are a better measure of pure sensorineural hearing loss such as NIHL.
The Vice-Chair was of the view that decisions using air conduction values have been relying on one particular sentence in the discussion paper that is somewhat unfortunately worded and that does not reflect the totality of the information in the discussion paper.
The Vice-Chair noted that none of the decisions allowing entitlement based on air conduction values released since the release of Decision No. 1052/17 has addressed the analysis in that decision.
Using the bone conduction values in the 2016 audiogram, the Vice-Chair concluded that the worker did not have entitlement for noise-induced hearing loss. The appeal was dismissed.