Incidents at work that would have little impact on some people can have devastating consequences for others. The point was strikingly made by the case of a call centre operative who claimed to have suffered a life-changing acoustic shock when his headset emitted a sudden, intense, high-pitched crackling sound.

The man said that he experienced nausea, dizziness and a severe headache after being assailed by the sound and felt as if someone had put a knitting needle through his ear. Despite numerous examinations and a course of cognitive behavioural therapy, he has since endured tinnitus in both ears and sleep disturbance. Intolerant to loud noises, he has a fear of putting anything over or close to his ears.

He launched a personal injury claim against his employer at the time, asserting a failure to take reasonable steps to protect him against the risk of acoustic shock. In its defence, the employer staunchly denied liability. It argued, amongst other things, that no such risk was foreseeable and that the noise-limiting headset with which he had been provided was fit for purpose.

Following two hearings, the man's claim was summarily dismissed by a judge on the basis that it had no realistic prospect of succeeding in the absence of a report from an expert acoustic engineer. Without such a report, the man could not establish the level of noise to which he was exposed.

Upholding his appeal against that decision, the Court of Appeal noted that acoustic shock can result from a level of noise falling well below that which presents a risk of noise-induced hearing loss. In a call centre context, it has been known to arise from faulty equipment, misdirected tones from fax machines and modems or malicious acts such as a whistle being blown down a telephone line.

The employer had destroyed a recording of the incident prior to the man lodging his claim. It had also lost the headset he was using at the time. Both would have assisted in the preparation of an engineer's report and it would therefore be most unfair to block his claim because of the absence of such a report. An equipment test subsequently carried out by the employer was performed on a replacement headset of an entirely different type and was therefore irrelevant.

The Court concluded that the judge fell into error in treating the claim for acoustic shock as if it were a claim for noise-induced deafness and approaching the matter on the mistaken premise that the evidence of an acoustic engineer was critical to the success or failure of the man's claim. The ruling opened the way for him to proceed with his case to trial.