Noise Induced Hearing Loss and the Engineering Expert Witness
Finch Consulting Senior Consultant Teli Chinelis applies his knowledge of acoustics to explain noise induced hearing loss and the role of the engineering expert witness.
Finch is regarded as one of the leading providers of expert services, including engineering expert witness services, dealing with personal injury claims relating to occupational exposure to noise and vibration, having produced more than 10,000 reports in connection with these claims over the years.
Noise-induced hearing loss (NIHL) is hearing loss that is caused by exposure to sound. Hearing damage from noise exposure generally happens gradually, becoming noticeable over a number of years of exposure. But it can also happen very quickly, for example after exposure to noise from impacts or explosions. The damage suffered tends to be permanent.
In the United Kingdom, it is estimated that there are more than 10 million individuals (about 1 in 6) with some degree of hearing impairment or deafness. Over one million workers are exposed to levels of noise that put their hearing at risk, with 17 per cent suffering hearing loss, tinnitus or other hearing-related conditions as a result of exposure to excessive noise at work.
The last decade has seen a significant rise in the number of NIHL claims. By 2010 the insurance industry was reporting over 24,000 claims annually and by early 2015 the reported annual number from the Institute and Faculty of Actuaries was 87,000, though this dropped to 57,000 claims annually by the end of 2015. NIHL numbers fell over 2016, though they are still higher than they were in 2011 and 2012. The expert witnesses at Finch Consulting are almost always fully utilised and have been preparing more than 300 relevant reports annually for the past few years.
The vast majority of the instructions that engineering expert witnesses at Finch receive on NIHL claims are for a single joint expert role agreed by all parties to the case, to produce an objective, unbiased report for the Court. Claimants in these cases need to satisfy the Court, on the balance of probabilities, that they are suffering from noise-induced hearing loss, and aim to do so by bringing expert medical evidence proving sufficient noise exposure for noise-induced hearing loss; and proving that exposure with the Defendant(s) has made a (non-trivial) contribution to the total exposure. They are required to show negligence and aim to prove this by showing a breach of common law duty or statutory duty.
Medical experts nowadays usually refer to the Coles Guidelines in their diagnosis of NIHL. Specifically, in relation to the input of the acoustic engineer, Requirement R2(a) refers to the claimant’s Noise Immission Level (NIL) reaching at least a level of 100 dB. For instance if the claimant was exposed to a daily personal noise exposure level (LEP,d) of 90 dB for 10 years then NIL=90+10*log(10)= 90+10 =100 dB.
Apart from providing estimates of the claimant’s likely daily noise exposure and lifetime noise immission levels the engineering expert (who has experience in risk management) also reviews any actions that the defendant should have taken in light of guidance and (after 1990) the regulations in place during the claimant’s employment.
For a large proportion of the cases we are instructed on, relevant disclosure is absent or limited. Here, the engineering expert witness must use their skills, knowledge and experience to forensically recreate the work and working conditions, to advise the Court on the likely noise exposures, and the duties and responsibilities of employers at the relevant time. Finch’s experts typically have at least 20 years of experience in dealing with occupational exposure to noise and vibration, risk management, and regulatory standards. It is this in-depth experience and impartiality in reporting that exemplifies the assessments undertaken by Finch Consulting.
Finch Consulting is a professional services firm specialising in engineering, health and safety, environmental management and law. Its engineers, lawyers, specialists, and ex-regulators offer world class advice, investigation, training and representation to its clients in a very wide range of industries, including legal, financial and insurance, food and drink, leisure and entertainment, manufacturing, energy and waste, and defence.
If you would like further information about noise related hearing loss please get in touch.