Is automated screening audiometry as reliable as pure tone audiometry?

07 May 2021

It is considered prudent in noise induced hearing loss (NIHL) claims to seek a repeat audiogram to assist in assessing the reliability of a claimant’s medical evidence, particularly when only one audiogram is available.

BLM acted for both defendants in a recent NIHL claim where the claimant alleged noise exposure during employment with the first defendant between 1972 and 1975, and the second defendant between 1976 and 1977. Neither defendant had the benefit of any documents with which to refute the claimant’s allegations and Single Joint engineering evidence found that if the court accepted the claimant’s allegations the claimant would have been exposed to noise levels in excess of 90dB(A) lep’d.

Medical evidence

The claimant relied on medical  evidence from Mr Leith Tapponi, Consultant Otorhinolaryngologist. Mr Tapponi’s report was based on an audiogram taken at a hotel local to the claimant in 2016. The configuration of that audiogram was typical of NIHL, however, noting that the claimant worked in the fire service between 1978 and 2008, we decided to obtain his occupational health (OH) records from the fire authority.   

The OH records included screening audiograms dated 1996, 2000 and 2005. The 1996 and 2005 audiograms were not diagnostic of NIHL at all, and any audiometric features consistent with a diagnosis on the 2000 audiogram were limited to 6kHz, rather than 3-4kHz where one would more typically expect to see noise damage. The defendants sought permission to rely on a desktop report from Mr Green and the experts subsequently prepared a joint statement setting out the issues agreed and disagreed.

Are screening audiograms more reliable than pure tone audiograms?

The main point of contention and an increasingly common issue raised in NIHL litigation was whether the OH screening audiograms such as Bekesy audiograms are more, or less reliable than pure tone audiometry,

Both experts agreed that any deterioration in hearing thresholds following cessation of alleged noise exposure could not be attributed to employment with the defendants, however, Mr Tapponi did not consider the OH screening audiometry to be as reliable as the later pure tone test. There was significant deterioration visible on the audiometry from 2005 to 2016 despite no further alleged noise exposure. Mr Green referred to research by Southampton University1 in support of the assertion that errors in audiograms tend to make hearing thresholds worse, not better and that the OH audiometry would therefore be more reliable than the later 2016 test.

The claimant’s hearing thresholds across the three OH audiograms were reasonably consistent. Mr Green considered this to be an indicator that the audiograms were reliable, and disagreed with Mr Tapponi’s assertion that they were unreliable. A systematic review2 of 29 separate studies on automated threshold audiometry found no statistically significant difference between automated (computer controlled) threshold audiometry and manual (pure tone) audiometry.

Following disclosure of the joint statement the claimant discontinued against both defendants. On the face of the claimant’s medical evidence, medical causation was established, yet the claim was successfully refuted using the occupational health records from a subsequent employer.

OH audiometry can be more helpful particularly when the testing took place closer to the cessation of alleged noise exposure, even if those audiograms are automated screening audiograms rather than pure tone audiometry. This claim is a reminder of the importance of considering whether any current or previous employers of the claimant may have undertaken audiometric testing and to obtain OH records where available and appropriate.    

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1 Perspectives on Normal and Near Normal Hearing, University of Southampton Report No 200 October 1991

2 Mahomed et al 2014

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The first defendant was represented by Mark Stern, Paralegal in our Manchester Office, and Second Defendant, Holly Miles, Associate Solicitor in our Cardiff Office.

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Disclaimer: This document does not present a complete or comprehensive statement of the law, nor does it constitute legal advice. It is intended only to highlight issues that may be of interest to customers of BLM. Specialist legal advice should always be sought in any particular case.

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