The High Court has set a decisive framework for the diagnosis, measurement, and valuation of military noise‑induced hearing loss claims, rejecting the claimant experts’ novel theories, such as acceleration, synaptopathy and AI‑driven models. The Judgment confirms that NIHL occurs during exposure and delayed tinnitus is possible, but causation becomes evidentially weaker over time; losses under about 4 dB will usually be de minimis, with military audiograms upheld as reliable contemporaneous evidence. On quantum, the court reinforced orthodox principles on PSLA and hearing aids, resisted mechanistic use of the Ogden Tables in future loss of earnings claims, and preferred individual evaluation.
CLB/LCB was not viewed as applicable for military claims (but not disapproved in other civil claims) and the court endorsed the revised Prof. Moore rM‑NIHL guidance – while emphasising case‑specific clinical judgment
In David Abbott and Others v Ministry of Defence [2026] EWHC 941 (KB),], Mr Justice Garnham ruled on a series of generic scientific and legal issues at the heart of the litigation which involves more than 50,000 former service personnel claiming Noise‑Induced Hearing Loss (NIHL) and tinnitus (through Hugh James and other claimant firms) from exposure to gunfire, explosions, aircraft and heavy equipment during service.
While most liability issues were settled in 2024, the MOD continued to dispute the claimants’ approach to diagnosing and measuring hearing loss referable to military service. Six test cases plus a number of reserves were originally selected, although only two proceeded to judgment following late compromises and discontinuances. Despite this, the court held that those cases adequately addressed the issues in dispute.
This article provides a summary of the generic issues and the outcome of the two remaining test cases. The claimant test case (C Lambie v MOD) considers appropriate awards for future loss of earnings and underscores that severity of injury does not automatically translate into substantial future earnings loss – especially where the evidence shows adaptability, hearing aid mitigation, and sustained career success. The defendant test case (J Craggs v MOD) provides a detailed illustration of the evidential and forensic difficulties that arise in military noise‑induced hearing loss (NIHL) litigation and reinforces the principles set out in Woodrup v Nicol [1993] PIQR Q104 (CA) relating to hearing aids.
Military Noise Is Different
A central finding of the judgment is that military noise exposure (which is regularly ‘impulsive’ in form) has features which are fundamentally different from civilian or industrial noise (or so-called ‘broadband’ exposure). Accepting expert evidence from ENT specialists, epidemiologists and auditory neuroscientists, the court recognised that impulsive noise – such as rifle fire and explosions – can cause distinct patterns of inner‑ear damage.
These patterns may include high‑frequency hearing loss which is maximal at 6-8 kHz, greater asymmetry between ears, and the absence of the classic ‘notch’ at 4 kHz typically seen in factory‑based noise cases. The court held that this distinction had been insufficiently reflected in traditional diagnostic models, which were generally directed to broadband industrial noise exposure.
Below is a summary of the main battlegrounds between the parties and the findings of the court.
1. Does hearing loss accelerate after noise exposure ends?
The claimants advanced a bold proposition: that exposure to intense military noise does not merely cause hearing loss coterminous with the period of exposure, but accelerates future age-associated deterioration, even where service audiograms during military service and at discharge show little or no immediate damage. By this mechanism, hearing loss was said to ‘progress’ after exposure ended due to this prior noise. The rate and likely progress of post-exposure hearing loss was defined by the claimants in a number of ways, none entirely consistent. They also had considerable difficulty in formulating how the theory worked in individual cases. This theory clearly had major implications for all forms of occupational Noise-induced Hearing Loss claims as it was not said to be confined to military cases.
The mechanism relied on was the consumption of the ‘cochlear reserve’ – the idea that noise depletes a hidden surplus of hair cells, allowing age‑related decline to surface earlier or progress faster.
The court accepted that this theory had some intellectual coherence and was supported to a degree by animal studies, particularly in mice. But that was clearly not enough to satisfy evidential requirements. Human evidence was limited, contradictory, or methodologically weak. Key longitudinal studies did not show faster decline in noise‑exposed populations. Nor was the theory endorsed by standard‑setting bodies or public authorities. As such the claimants failed in their contentions in this area (a failure also illustrated in the leading case of Craggs).
Bottom line: acceleration remains an interesting hypothesis, but the orthodox view holds – where noise‑induced hearing loss occurs, it will be audiologically apparent during exposure, not decades later. Crucially, even if acceleration was real, there is no way to identify or quantify it in an individual claimant. The claimants therefore failed to surmount either hurdle.
2. Cochlear synaptopathy: real science or dead end law?
Cochlear synaptopathy – sometimes branded ‘hidden hearing loss’ – has gained traction in recent years. It refers to damage to the nerve connections between hair cells and the brain, potentially causing speech‑in‑noise difficulty or tinnitus even when audiograms look normal.
The court accepted that synaptopathy is a genuine pathological phenomenon, well‑established in animals and probably present in humans. It also accepted that extreme military noise might cause it (although by this stage there would have been audiogram evidence of hearing loss anyway).
And here, science ran into a legal wall.
Synaptopathy cannot be diagnosed or measured during life. There is no gold‑standard test, no agreed proxy, no reliable way to separate noise effects from ageing – and no method of tying alleged synaptic loss to functional disability in a specific person.
As one influential paper put it: “The search for noise‑induced synaptopathy in humans may be mission impossible”.
Bottom line: scientifically intriguing, medically unresolved – and legally unusable. A scientific demonstration of the possibility of synaptopathy cannot, on the current evidence, prove causation or damage. Even the claimants admitted that quantifying any such synaptic loss in an individual was currently impossible. The claimants therefore failed to demonstrate their case on synaptopathy.
3. Tinnitus: timing matters, but there is no stopwatch
All parties accepted that tinnitus is common, subjective, and incapable of objective proof. The dispute was about delay: can tinnitus that begins years after service still be attributed to military noise? This was the claimants’ case and would have led to a validation of all tinnitus claims where a claimant had prior noise exposure, regardless of how many decades had elapsed. This was of considerable significance given the high percentage of the population who report such symptoms in the absence of noise exposure.
In contrast, public bodies have often suggested a pragmatic one‑year cut‑off between the end of exposure and the initiation of any symptoms. Claimants argued that this was crude, unsupported, and contradicted by clinical experience.
The court rejected both approaches. The claimants’ extreme approach was rejected. Equally, there was no scientific basis for an absolute time-limited cut‑off. However, the court accepted that in general terms delay weakens causation. The closer the tinnitus begins to the noise exposure, the stronger the inference. As time passes, scrutiny must increase – of alternative causes, consistency of account, and credibility.
Bottom line: delayed‑onset tinnitus is possible but never assumed. Each case stands or falls on its facts and on the medical evidence.
4. How little is too little? The de minimis boundary
Noise damage that leaves a person no worse off is not actionable (i.e., it is regarded at law as ‘de minimis’). The question was where to draw the line in NIHL claims.
Expert consensus pointed to a practical threshold: hearing loss below 4 dB (on a binaural average) is generally immaterial and therefore could be classified as de minimis.
But the court resisted turning this into a hard rule. Audiograms measure tone detection, not real‑world communication. Exceptional cases – for example, proven speech‑in‑noise difficulty – might still cross the legal threshold. Nevertheless, this is an important precedent in both military and civilian cases.
Bottom line: NIHL under 4 dB will usually be de minimis, but not automatically.
5. Prof. Moore Multi-Layer Perceptron Method (MLP 18) and obsolete models (M-NIHL) rejected
The court gave short shrift to the claimants’ attempt to rely on artificial intelligence in diagnosing hearing loss. A machine‑learning model known as MLP (18), promoted for its apparent accuracy, was rejected entirely. MLP was criticised as a ‘black box’ incapable of explaining how individual diagnoses are reached, with the court concluding that such opacity is incompatible with litigation.
The court also rejected any use of the earlier versions of the Military NIHL methodology (M-NIHL 2020), described as obsolete and unreliable, and ruled they should not be used as a fallback where claimants fail to meet the revised criteria (see below).
6. Military audiograms upheld
In a further blow to the claimants’ arguments, the court rejected suggestions that military screening audiograms are inherently unreliable and therefore could not be relied upon in assessing a claimant’s audiological history. While acknowledging they are less precise than clinical tests, the judge found that, when viewed as part of a series, they often provide valuable contemporaneous evidence of hearing history and deterioration. This is obviously of great importance in latency claims where the contemporary military audiograms demonstrate no hearing loss at discharge.
Attempts to portray military audiometry as systemically flawed were described as overstated and unsupported by robust evidence.
7. CLB guidance inapplicable for military claims
For decades, the CLB guidelines have been widely used to diagnose industrial NIHL. While CLB remains suitable for civilian noise cases, the court held that it was not appropriate for military claims given the impulsive nature of military noise and the patterns of higher frequency loss exhibited in studies. Applying it to armed forces exposures risks under‑diagnosing genuine injury, the court found.
Instead, the court adopted the revised Prof. Moore Military Noise‑Induced Hearing Loss (so-called ‘rM‑NIHL’) guidelines as the preferred diagnostic framework for military cases. However, the judgment stopped short of imposing mandatory rules, emphasising that medical experts must still exercise clinical judgement based on all available evidence.
8. How hearing loss should be measured
On quantification, the court favoured the rM‑NIHL approach over the defendant’s LCB method, recognising that military noise can cause significant loss at higher frequencies that traditional methods would underestimate. This not unsurprisingly followed the adoption of this alternative approach for diagnosis.
The Judge confirmed that contemporary population data – ISO 7029:2017, corrected in 2024 – should replace outdated data sets from the 1980s and earlier. The court rejected the claimants’ first line argument that no baseline correction was required and instead ruled in favour of their alternative proposition that a 2.4 dB correction should be applied at each frequency to reflect normative hearing at age 18 in population cohorts.
The court also rejected automatic deductions at 6 kHz for use of TDH39 headphones, holding that such adjustments must be made on a case‑by‑case basis. However, it accepted that there was an artefact at this frequency which required consideration, particularly in boundary cases.
The use of rM-NIHL was not unqualified. It was subject to the following further findings and modifications.
a) Experts should not routinely apply the 50th percentile AAHL which assumes every individual has average age associated hearing loss ‘but for’ the noise exposure. This was the starting position of rM-NIHL. Instead, the expert should consider all the available audiometry, including military screening tests to establish into what percentile any given claimant fell. This was an important qualification to the method and will have significant implications for quantification.
b) The conventional 1,2,3 kHz average should continue to serve as a baseline descriptor in assessing disability. However, it is legitimate to consider supplementary metrics incorporating 4 khz where speech in noise difficulties is found to be prominent.
c) NIHL should generally be quantified using the traditional 4:1 binaural calculation, however again this is open to clinical judgement in individual cases where the excess loss calculation does not reflect the level of disability.
d) It is recorded in the judgment that the rM-NIHL method was developed based on the audiograms of individuals who were all men aged 60 years or below. Therefore, the experts agreed that the Moore methods should be used with caution for women or men aged above 60 years.
9. Damages and hearing aids: realism over theory
The court reaffirmed orthodox principles on damages:
On hearing aids, the court accepted that private, high‑performance digital aids may be recoverable – provided the claimant proves intention, benefit, and proportionality. There are no universal rules and there is no automatic entitlement.
Further comments on PSLA, hearing aids, and future loss of earnings are considered in the summary of the test cases below.
Christopher Lambie v Ministry of Defence (claimant test case)
Ogden tables and the Limits of Statistical Abstraction
In Lambie v Ministry of Defence, the High Court considered the appropriate assessment of damages for a 46-year-old senior defence‑sector consultant with long‑standing, service‑related Noise‑Induced Hearing Loss (NIHL). Liability was largely agreed, leaving disputes as to general damages, hearing‑aid costs, and – most significantly – future loss of earnings.
While the court accepted that Mr Lambie suffered severe NIHL and was disabled within the meaning of the Equality Act, it firmly rejected a substantial Ogden‑based claim for future loss of earnings. Instead, the judge awarded a modest Smith v Manchester sum, emphasising the need for individual evaluative judgement and caution against mechanistic application of actuarial tables.
Future loss of earnings: Ogden or Smith v Manchester?
The principal issue was whether Mr Lambie’s future earning capacity should be assessed by:
The claimant advanced an Ogden‑based claim exceeding £370,000, relying on arithmetical disabled reduction factors and the argument that disability must be assessed without hearing aids. The defendant contended that this produced an unrealistic and unjust outcome.
Judicial approach to the Ogden Tables
The judge undertook a detailed review of the authorities, particularly Billett v Ministry of Defence [2015] EWCA Civ 773, and emphasised several recurring principles:
The court noted that even in cases where Ogden was used (such as Barry v MoD [2023] EWHC 459 (KB)), judges routinely adjusted reduction factors to reflect the claimant’s actual employment resilience, determination, and mitigation.
Importantly, the court was not shown any authority in which the raw disabled reduction factors had been applied without qualification.
Distinguishing the key authorities
The judge distinguished this case from Barry v MoD, where the claimant:
By contrast, Mr Lambie had:
While his NIHL could reduce his chances of promotion and disadvantage him on the open labour market, those risks were contingent, imprecise, and not amenable to actuarial calculations.
Preference for individual evaluation
Echoing the observations of Andrew Edis KC at first instance in Billett, the judge emphasised that reliance on population statistics must not displace judicial assessment of the actual claimant based on the evidence in the particular case.
The court rejected the argument that disability under the Equality Act necessarily equates to Ogden disability in every case, stressing the importance of residual functional capacity, including the effects of assistive technology (hearing aids).
The court held:
Jack Craggs v Ministry of Defence
Hearing loss, tinnitus, credibility and the limits of hearing‑aid claims
Mr Craggs (46 years old) served between 1998 and 2002. While liability was admitted subject to reduction under the so-called ‘Matrix Agreement’, causation was firmly in dispute. The case ultimately turned on credibility, contemporaneous audiometry, and the proper limits of claims for hearing aids where hearing loss was mild, disputed, or unconnected to service.
The issues
The court was required to determine four principal questions:
Credibility and lay evidence
The judge was unequivocal in his assessment of Mr Craggs as a witness on the issue of hearing loss. His evidence was described as evasive, inconsistent and, in some respects, deliberately misleading.
These matters led the court to conclude that no weight could be placed on Mr Craggs’ evidence unless corroborated by objective evidence. His account of hearing loss during service and in the years following discharge was rejected.
By contrast, the court accepted that Mr Craggs gave consistent evidence about the onset of tinnitus in service, supported by contemporaneous complaints to his mother. The judge regarded tinnitus as the one area in which the claimant’s account was both coherent and reliable.
Audiometric and expert evidence on hearing loss
It was common ground that by 2017 and thereafter Mr Craggs’ audiograms demonstrated asymmetric features consistent with NIHL, particularly in the left ear. This was long after he had left. However, the central dispute was when that damage occurred.
The court preferred the defendant’s case that:
The court also rejected arguments based on delayed or latent noise injury, applying its broader conclusions in the litigation that NIHL does not emerge decades after exposure (supra).
The conclusion was that Mr Craggs’ hearing loss was not proven to be caused by military service, and the NIHL claim failed.
Tinnitus: Causation and severity
On tinnitus, the evidential picture was materially different. Both ENT experts agreed that Mr Craggs suffered from tinnitus. No alternative cause than noise was suggested, and the onset in service was accepted if the oral evidence on this point was likewise accepted.
However, the court scrutinised the onset and severity of the condition carefully. Mr Craggs had given differing accounts to different clinicians, at times suggesting that tinnitus did not disturb his sleep. As a result, the court rejected the more severe descriptions advanced at trial.
The condition was assessed as lying between the upper end of ‘mild’ and the lower end of ‘moderate’ tinnitus, resulting in an award of £19,000 for PSLA, rather than the higher figure claimed.
Hearing aids: A cautious and restrictive approach
Hearing aids for hearing loss
Because the court found that Mr Craggs’ hearing loss was not caused by military service, there was no basis in principle for awarding the cost of hearing aids in relation to it.
Even leaving causation aside, the expert evidence indicated that:
This aspect of the claim therefore failed entirely.
Hearing aids for tinnitus management
The claimant also advanced the argument that hearing aids were justified as a means of managing tinnitus. The court rejected this for several reasons including:
The court was also influenced by the claimant’s conduct. Despite asserting symptoms of both tinnitus and hearing loss for many years, he had never sought NHS or private hearing aids and even following a litigation‑arranged trial had taken no steps to obtain them.
Applying Woodrup v Nicol, the court concluded that a claimant cannot recover the cost of private medical equipment which he is unlikely, in reality, to obtain.
Accordingly, no award was made for hearing aids or tinnitus‑masking equipment. Only a limited sum (£445) for tinnitus counselling was allowed.
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