His Honour Judge Bird in Bevan v Ministry of Defence [2025] EWHC 1145 (KB) has set out, in this recent judgment, the relevant diagnostic criteria in claims for acoustic shock.

Mr Bevan claimed damages for hearing loss, tinnitus (the primary injuries) and a “conversion disorder” (the secondary injury). If the primary injury was not caused by the negligent exposure, then the secondary injury also falls away.

Mr Bevan was employed by the Ministry of Defence (MOD) between 2017 and 2020, and alleged being negligently exposed to dangerous and unsafe levels of noise by the defendant whilst working on and testing Ajax armoured vehicles made by General Dynamics. He was taught how to drive the vehicles and how to operate their weapons systems. He was also required to use a right sided headset whilst inside the vehicles, which was used for communicating with others and to receive alarm warning from the vehicle. Noise exposure was alleged from the vehicles and from the headset. In and around November 2020, the MOD barred the use of the headset.    

Breach of duty was admitted. Causation and quantum were in dispute.

Professor Wright for the claimant and Mr Parker for the defendant gave oral evidence at trial.

As the claim progressed, noise induced hearing loss was ruled out as a potential diagnosis on the basis that Mr Bevan’s audiogram did not satisfy requirement 3 of the Coles, Lutman and Buffin 2000 Guidelines as there was no qualifying notch or bulge. Acoustic trauma was also ruled out as a potential diagnosis on the basis that acoustic trauma can be described as physical damage caused by a very loud noise. There was no evidence that the noise levels were sufficient to achieve a diagnosis of acoustic trauma, thus leaving acoustic shock as the only potential diagnosis remaining.

The only description of the diagnostic criteria for acoustic shock was contained in the paper entitled “acoustic shock: an update review” by Mr Andrew Parker and Mr William Parker. This paper updates the previous paper on acoustic shock written by Mr Parker and post-dates the Court of Appeal decision in Royal Opera House Covent Garden Foundation v Goldscheider [2019] EWCA Civ 711. The 2020 paper adds descriptors G1 to G4 – also known as the “Grindleford Criteria”.

The Grindleford Criteria

G1 - There must be a defined acoustic incident (which need not be negligent).

G2 - Ear symptoms should start straight away or shortly afterwards.

G3 - Ear symptoms should be outside physiological or startle responses.

G4 - Ear symptoms should be experienced in or arise from the exposed ear(s).

There may be significant psychological overlay or relationship to illness behaviour.

Mr Bevan’s exposure to noise was regular, it was repetitive, and it was broadly predictable. There was no suggestion of any particular and unusual noise or of any day or days when things were worse than usual. There was no memorable or unusual one-off acoustic event.

At routine health testing in November and December 2020, Mr Bevan denied suffering from tinnitus, and it was not until March 2021 that Mr Bevan reported tinnitus symptoms. An audiogram on that day showed “normal hearing thresholds”. Mr Bevan told Mr Parker that the onset of the bilateral tinnitus was after the Ajax project.  

Mr Parker’s firm view was this this is not an acoustic shock case, despite G3 being satisfied by Mr Bevan. The claim was dismissed on the basis that the claimant failed to satisfy three of the four diagnostic criteria/indicators for acoustic shock.

Impact of judgment

Industrial deafness practitioners will no doubt welcome this High Court decision, which provides clarity in cases of acoustic shock. The “Grindleford Criteria” should now be the accepted set of guidelines used by medical experts to diagnose acoustic shock. 

It is also a reminder to practitioners that acoustic engineering evidence is still required in these types of cases, even when breach of duty has been admitted. Without acoustic engineering evidence, and an examination and assessment of the noise levels generated by the machinery and equipment, a diagnosis of acoustic trauma should not be ruled out.