In this article, Dr Robert MacKinnon, a clinical scientist with a PhD in otorhinolaryngology, examines the current clinical and medicolegal understanding of acoustic shock and how it has evolved in recent years.
Drawing on key case law and developments in the clinical literature, he explores how acoustic shock is distinguished from noise-induced hearing loss and acoustic trauma, and considers the application of the Grindleford Criteria in defining and assessing claims in 2026.
Noise and its effects
There is thankfully now reasonable awareness of the long-term consequences of exposure to loud noise – we know from initial studies of jute weavers in Dundee (Taylor et al. 1967) that long-term exposure to loud noise over 85dB(A) can lead to noise-induced hearing loss as measured on the audiogram, and other symptoms of “auditory suffering” (Meyer-Bisch, 1996) like tinnitus (a ringing or buzzing in the ears when there is no external sound) or hyperacusis (finding everyday sounds unpleasantly or painfully loud and intrusive).
There are also some sounds that are so loud that a single exposure to them can cause similar issues or physical damage to the inner ear. Exposure to the sound of gunshots can be enough to cause issues that are potentially permanent over a short period of time, and even louder sounds, as large waves of pressure such as those from explosive detonations, can physically shear the delicate structures of the cochlea apart. This is termed acoustic trauma (McFerran and Baguley, 2007).
However, there is another area of exposure to noxious noise which has increased in incidence but perhaps hasn’t had the same widespread understanding of what it is and what its impact can be. This is the phenomenon of acoustic shock.
What is Acoustic Shock?
The Health and Safety Executive defines acoustic shock as relating to “incidents involving exposure to short duration, high frequency, high intensity sounds through a telephone headset”, which gives us a starting point and some historical context of when it was first reported. A better general definition is provided by the Royal Victorian Eye and Ear Hospital, who state “Acoustic shock (AS) is a psychological shock response from exposure to a sudden, brief and unexpected loud sound.”
It was documented in a clinical context in 2007 in the UK as affecting call-centre staff (McFerran and Baguley, 2007). This paper defines acoustic shock as “a symptom cluster that includes [ear pain], altered hearing, [ear] fullness, imbalance, tinnitus, dislike or even fear of loud noises, and anxiety and/or depression”.
Cases were reported in Denmark, Australia and the UK, sometimes with callers deliberately playing unpleasant and loud sounds down the phone. Inciting sounds were noted by the studies reviewed as being between 56-120dB in intensity and in the frequency range 100Hz-3.8kHz. They typically had a very rapid onset, meaning the operator did not have opportunity to move the handset away from the ear (an action considered much harder to do with a headset).
Others have expressed scepticism over the condition; Hooper (2014) suggests that on account of the variation in inciting sound, time of symptom onset, clusters of cases in call centres, and coincidence of work-related issues, acoustic shock is “predominantly psychogenic” and that “malingering is a factor in some cases”. Wider opinion in the clinical literature has moved towards it being recognised rather than dismissed (Parker et al. 2020) but it is far from a closed book at the time of writing.
In a medicolegal context:
It has been widely reported in the press, dating back to 1998, that there were a growing number of claims emerging for employees suffering with acoustic shock caused by wearing headsets. Predominately, these were claims brought by employees through their trade union, the Communication Workers Union, against British Telecom. Given the expansion of call centre work, it is perhaps surprising that more cases were not reported during this time.
However, the profile of acoustic shock was raised significantly in 2018 when the case of Goldscheider v The Royal Opera House ([2018] EWHC 687 (QB)) was heard, resulting in a £750,000 settlement. Here, a viola player claimed that during a rehearsal of Wagner’s Die Walküre in 2012 he was exposed to music from the brass section in excess of 130dB(A), which he felt was “excruciatingly loud and painful” and “a wall of sound which was completely different to anything he had previously experienced.”The case was successfully argued (and upheld on appeal) that professional musicians should be afforded the same protection as contained in the Control of Noise at Work Regulations 2005 (now revised 2021) and that loud music should be treated as noise as in any other occupational setting, with hearing protection zones in force.
Notable too was the recognition of acoustic shock as a distinct clinical entity from acoustic trauma or noise-induced hearing loss. It was ruled to stem from an “acoustic incident, the sudden onset of loud noise for which the person is unprepared”, triggering a startle response (e.g. contraction of the stapedius muscle to try to reduce the sensitivity of the auditory system and limit further exposure) and then the build-up of “toxic metabolites” from overstimulation which provide the physiological basis of harm, which could manifest as “deafness, pain, tinnitus or dizziness or a combination of two or more”. (Point 110; [2018] EWHC 687 (QB)). Such specificity might not be supported by the clinical literature, but these comments at least give a starting point for better defining the condition in this context.
In this case, an audiometric hearing loss was noted, but from the description above may not necessarily be present in acoustic shock, which focuses on other hearing-related symptoms. This is consistent with a review of clinical and medicolegal cases published around the same time (Parker et al. 2014), which noted normal examination results in 93% of cases and normal audiometry results in 43% of cases. It is worth noting that previous ear-related pathology was present in 90% of cases and psychopathology in 63% of cases.
Looking forward – The Grindleford Criteria
The strongest current diagnostic criteria were highlighted in Bevan v Ministry of Defence [2025] EWHC 1145 (KB). These were from an update by Parker et al. to this 2014 paper. Parker et al. (2020) proposed the following so-called “Grindleford criteria”:
The Grindleford Criteria
1 – There must be a defined acoustic incident (which need not be negligent).
2 – Ear symptoms should start straight away or shortly afterwards.
3 – Ear symptoms should be outside physiological or startle responses.
4 – Ear symptoms should be experienced in or arise from the exposed ear(s).
There may be significant psychological overlay or relationship to illness behaviour.
These were peer-reviewed in a clinical context as part of the paper’s publication and were applied by his Honour Judge Bird in this 2025 case, potentially setting precedent in their wider application in medicolegal cases.
Closing thoughts
In cases where a loud sound has allegedly caused harm, the approach of separating out noise-induced hearing loss (for chronic sound exposure), acoustic trauma (for physically damaging intense sound) and acoustic shock (a persistent adverse effect of an unexpected loud noise exposure unlikely to cause noise-induced hearing loss) may be advisable. In the case of the latter, applying the Grindleford Criteria remains the current most likely guide for defining a case.
References
Health and Safety Executive (2021) – Control of Noise at Work Regulations (3e) ISBN: 9780717665679
Hooper RE. Acoustic shock controversies. The Journal of Laryngology & Otology. 2014;128(S2):S2-S9. doi:10.1017/S0022215114000309
McFerran DJ, Baguley DM. Acoustic shock. J Laryngol Otol. 2007 Apr;121(4):301-5. doi: 10.1017/S0022215107006111. Epub 2007 Feb 19. PMID: 17306048.
Meyer-Bisch C. Epidemiological evaluation of hearing damage related to strongly amplified music (personal cassette players, discotheques, rock concerts)–high-definition audiometric survey on 1364 subjects. Audiology. 1996 May-Jun;35(3):121-42. doi: 10.3109/00206099609071936. PMID: 8864255.
Parker W, Parker V, Parker G, Parker A. ‘Acoustic shock’: a new occupational disease? observations from clinical and medico-legal practice. Int J Audiol. 2014 Oct;53(10):764-9. doi: 10.3109/14992027.2014.943847. PMID: 25201133.
Parker, W.A.E., Parker, V.L., Parker, G. & Parker, A.J. 2020, “Acoustic shock: an update review”, The Journal of laryngology and otology, vol. 134, no. 10, pp. 848-853.
Taylor W, Pearson J, Mair A. Hearing thresholds of a non-noise-exposed population in Dundee. Br J Ind Med. 1967 Apr;24(2):114-22. doi: 10.1136/oem.24.2.114. PMID: 6023076; PMCID: PMC1008541.