David Abbott & Ors v Ministry of Defence

In military noise-induced hearing-loss litigation, diagnosis remains a matter of clinical judgment informed by, but not mechanically determined by, diagnostic guidelines. The revised military method, rM-NIHL, is preferred; CLB is generally unsuitable because military impulse noise may produce different audiometric patterns, including high-frequency damage and no notch or bulge. The original M-NIHL method and the opaque MLP(18) method should not be relied on in medico-legal work.

Quantification should use ISO 7029:2017/2024, with a 2.4 dB baseline correction, and a percentile selected clinically from all available audiometry. Sensitivity and specificity figures are only approximate; positive predictive value is more useful but not determinative. Delayed progression of hearing loss remains unproven. Delayed tinnitus requires increasingly careful scrutiny, but no arbitrary cut-off applies.

The judgment determined generic issues arising in a large cohort of claims by former members of the armed forces for noise-induced hearing loss and tinnitus. The litigation was conducted through lead cases and agreed generic issues, following settlements and withdrawals that left the claims of Christopher Lambie and Jack Craggs for determination.

Liability was admitted in Lambie subject to the parties’ Matrix agreement, but quantification, damages, hearing-aid costs and future earning capacity remained in issue. In Craggs, causation of hearing loss and tinnitus, damages, hearing aids and tinnitus treatment were disputed. The central questions concerned the reliability of military audiograms, the appropriate diagnostic and quantification methods, delayed progression, cochlear synaptopathy, tinnitus, de minimis injury and consequential losses.

1. Generic issues. BSA-compliant pure-tone audiometry is the best evidence, but military screening audiograms may assist diagnosis and quantification where they form a consistent series. All audiometric evidence should be considered in context and as a whole. ISO 7029:2017/2024 was preferred to ISO 7029:1984/2000, with a general 2.4 dB baseline correction across 1–8 kHz. TDH39P earphones may produce variable 6 kHz results; no automatic 6 dB deduction should be made.
2. Diagnosis. The original M-NIHL method was superseded by rM-NIHL and should not be revived as a fallback because its poor specificity led to the revised method. MLP(18) was unsuitable for litigation because its operation could not be understood or challenged. CLB was generally unsuitable for military cases, since military impulse noise may cause different and more variable audiometric patterns, including damage at 8 kHz and the absence or disappearance of a notch or bulge. rM-NIHL was the preferred method, subject to clinical judgment and consideration of alternative causes.
3. Quantification. The Moore, Cox and Lowe method was preferred. The percentile should be selected by the medico-legal ENT surgeon from all available audiometry. The 1, 2 and 3 kHz average remains a baseline descriptor, but 4 kHz may properly be considered where speech-in-noise difficulty is important. The 4:1 binaural calculation is generally appropriate, subject to additional clinical assessment where it understates disability.
4. Other generic issues. Sensitivity and specificity were only ballpark estimates. Positive predictive value was more informative but not determinative. The theory of post-exposure acceleration was plausible but unproven and incapable of reliable individual identification or quantification. Cochlear synaptopathy could not be definitively diagnosed or quantified in living humans. No arbitrary temporal cut-off applied to tinnitus; later onset required more intensive scrutiny. Hearing loss below 4 dB was ordinarily de minimis absent other appreciable consequences.
5. Lead cases. Lambie recovered £39,000 for PSLA, £27,350 for hearing aids and £64,800 for loss of earning capacity, subject to a 10% Matrix reduction. Craggs failed to establish that his hearing loss was caused by military service, but established service-related tinnitus. He recovered £19,000 for PSLA and £445 for tinnitus counselling, subject to a 25% Matrix reduction; no award was made for hearing aids.

First-instance judgment determining generic issues and the two remaining lead claims. No appellate history was stated in the judgment.