Background of the Case
The claimant, Mr. Cook, worked for the defendant, Ketson, between 1975 and 1980. During this period, he was exposed to excessive noise levels. The claimant underwent three audiograms. The case concerned the assessment of the audiograms and whether a diagnosis of noise-induced hearing loss ("NIHL") could be made.
The defendant submitted that the Coles, Lutman, Buffin ("CLB") 2000 Guidelines should be used. This is a paper now over two decades old but used by the court as the standard method of assessment. The claimant argued that the relatively new Moore, Lowe and Cox ("MLC") 2022 paper should be used. The difference between the two is that under the CLB Guidelines, the claimant would not establish causation on the balance of probability, but he would under the MLC Guidelines.
Key Issues and Findings
The claimant only claimed excessive noise exposure at work with Ketson. The noise level was accepted to be typical broadband steady noise. Joint engineering evidence concluded that the claimant was exposed to a lifetime noise immission level ("NIL") of 96.8dB(A).
The medical experts, Mr. Hisham Zeitoun for the claimant and Mr. Kevin Green for the defendant, agreed that the most reliable audiogram did not meet CLB criterion R3(b). This requires notches or bulges in the audiogram to be ≥20dB at the noise-sensitive frequencies. This criterion indicates unusual sensitivity to noise damage, which the experts therefore agreed the claimant was not. The audiogram(s) did meet criterion R3a (notches or bulges of ≥10dB but less than ≥20dB), but the claimant's lifetime noise dose fell short of the 100dB(A) required to show causation under R3a.
The claimant's team argued that noise-induced hearing loss could be diagnosed with a lower level of lifetime noise exposure than the CLB Guidelines permit, citing the MLC paper.
The MLC Paper
Moore, Lowe and Cox are frequently instructed by claimant firms in noise-induced hearing loss. The authors argue that the diagnostic criteria commonly employed in the UK lead to many people with a history of noise exposure and hearing loss not being successful in claiming for noise-induced hearing loss. The authors criticise the CLB Guidelines for setting too high a bar for establishing causation in that it requires a NIL of 100 dB(A) or higher to prove causation for those with bulges of between 10dB and 20dB.
The authors cite evidence from Passchier-Vermeer (1974) that lower noise exposure levels can still lead to hearing loss in some individuals. Their evidence was that exposure to steady noise of 90 dB(A) NIL led to a hearing loss of 11 dB at 4 kHz for the 10th percentile. The MLC therefore recommend a NIL of 90 dB(A) with no lower limit on LEP,d for all cases of exposure to broadband steady noise.
Judgment
The court was not persuaded to use the MLC Guidelines instead of the CLB Guidelines on the basis that the MLC Guidelines are not concerned with the standard of proof in civil claims, that being the balance of probabilities. This contrasts with the explicit considerations made in the CLB Guidelines, which explain that “these guidelines have been derived after careful consideration of the data available and keeping in mind the legal criterion that the diagnosis should be likely ‘on balance of probabilities’ or ‘more likely than not’.”
At paragraph [50] of the judgment, Mr. Recorder William Evans said: "If 90% of a population with a particular level of hearing loss having been exposed to a particular level of noise have suffered the hearing loss from a cause that was not the noise then it is impossible to say that it is more likely than not that the hearing loss of any one person of that population has been in fact caused by the noise. It is more likely than not to have been caused by something other than noise exposure. Moore et al consider fairness to a claimant requires only that the noise level should cause hearing loss in a “reasonable proportion” of individuals. It appears they consider that such a reasonable proportion is 10%. It is the duty of the court to be fair to all parties and to apply the relevant legal principles to the evidence. The problem with the Moore et al criteria is that if the suggested NIL causes a hearing loss in only a small proportion of individuals it cannot be said that in each individual case it was in fact caused by noise because it is more likely not to have been.”
Then at paragraph: [51] "They also fail to explain why it is they consider that a proven noise level which causes NIHL in 10% of the exposed population can possibly amount to proof of causation on a balance of probability in all such persons exposed.”
Implications for Future Cases
Although this is a first-instance decision and not binding, the judgment is likely to be persuasive in future noise-induced hearing loss cases as it was heard by a judge experienced in disease claims. The MLC Guidelines have long been pushed by claimant firms as a replacement for the ubiquitous CLB Guidelines, which would result in many more people being diagnosed with NIHL. A study in 2024, undertaken by the ENT Consultants Lutman, De Carpentier and Green, found that the MLC Guidelines falsely diagnosed NIHL at a rate of 56%, significantly more than the CLB Guidelines (37%).
This judgment confirms the court will still be concerned with the balance of probabilities and that for now, in typical broadband steady noise at least, the CLB Guidelines remain the best method available to practitioners and the court for assessment of causation in NIHL claims.
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