A day in the life of an Acoustics Expert Witness

Back in 2017, the job and recruitment website Glassdoor published a list of ten of the weirdest job titles in the UK. The second job title in the list was that of an Acoustics Consultant accompanied with the following description “working on engineering projects, an acoustics consultant has a good understanding and practical experience of environment and building acoustics and is expected to be proficient with technology called “noise mapping software”. An acoustic consultant would need to be confident with a range of acoustics and vibration measurement and analysis systems, and be conversant with relevant standards and guidance, especially those relating to environmental acoustics”.

I wonder how much weirder the job title I normally use nowadays, that of an Acoustics Expert Witness must be to the populace. The reason I often use this title, is because more than 60% of my day-to-day work is as an expert witness rather than an expert advisor or acoustics consultant (see Glassdoor’s description above). I understand that there may be only a handful of us that would agree to use such a title, and sometimes I wonder whether I should continue using it, due to how incredibly niche it is. The overall business market appears to prefer generalists over specialists, however in legal related work, specialism is still king. So perhaps I should only use it when communicating with solicitors rather than construction-related professionals. 

Back in 2019[1] nine industry federations and representative bodies jointly called for collaboration to boost availability of occupations in greatest shortages. They wanted to see the industry work together to accelerate recruitment for 18 severe shortage roles in industry. Due to the list being in alphabetical order, the first role that appeared was that of “acoustic engineers”.

You will find that the majority of the handful of Acoustics Expert Witnesses in the UK are members of the Institute of Acoustics, which has around 3000 members. The percentage of such witnesses would be higher in the membership of the Association of Noise Consultants, which numbers around 100 companies that have a combined employee count of around 1000. So from these circa 1000 Acoustics consultants only the most senior would normally act as expert witnesses, and I would guess that this number would be around 100, and the vast majority of these would prepare say one or two expert witness reports in a year, and even for the very few that would prepare say around 10 reports in a year, this workload would constitute less than 50% of their billing time (and most of these experts do have intensive managerial roles). When I googled “list of expert witnesses in acoustics”, a list of only 13 names came up (and thankfully I was included in that list).  Suffice to say then that Acoustics Expert Witnesses are indeed rare.

Need for Acoustic Consultants and Acoustics Experts

You may argue that the low number of Acoustics Consultants in general is simply due to the low demand for such services sprouting from a low need. However, the Frontiers Report published by the UN Environment Programme (UNEP)[2] in February 2022 identified noise pollution as one of three looming environmental issues (alongside wildfires and disruptive timing of life cycles) that merit attention and action from governments and the public at large.

Noise is the single largest issue of complaint made to local authorities in the UK. The Chartered Institute of Environmental Health (CIEH) published[3] in February 2020 the results of its flagship noise survey. A total of 143,054 noise complaints were recorded by these local authorities, 61 complaints for every 10,000 people. Residential noise accounted for the largest proportion of noise complaints.

According to a study^[4], Britons spend 92% of all their time indoors. The homes we live in have a significant influence on our health and wellbeing. Despite this, 20% of housing stock in England does not meet the national Decent Homes Standards^[5] according to the 2016 review of housing stock conditions.

Noise pollution is so harmful that, according to the World Health Organization (WHO), approximately one million Healthy lives are lost every year as a result of exposure to environmental noise[6].

The WHO estimates that over 1.5 billion people globally live with hearing loss and this number could rise to over 2.5 billion by 2050. If hearing loss was officially considered a disability, it would rank as the highest disability class in the world[7]. Currently, it ranks as the highest work-related illness/injury in the UK[8]. In the UK, more than 40% of people over 50 years old have hearing loss, rising to more than 70% of people over the age of 70[9].

Nowadays, the effects of climate change appear to dominate most discussions and concerns, and a government economic study[10] has put the impact on climate change in England at an estimated annual social cost of £1 to £4 billion. However, the same study placed the cost of urban road noise alone at a significantly greater figure of £7 to £10 billion.

As such, we are indeed in great need of Acoustics specialists in order to assist in diminishing the negative impacts of noise pollution, so that we place a lesser weight on the environment, our bodies, and the planet.

Areas of action for Acoustics Expert Witnesses

Acoustics Expert Witnesses may provide their services in areas of planning, arbitration, civil and criminal law, however, their role is always the same. The Acoustics expert’s role whether at a hearing or inquiry for a planning appeal, at an arbitration tribunal or at court for a civil or criminal matter is to give evidence that is necessary or valuable to ensure that the inspector[11]/arbitrator/judge can make a fully informed decision. Within this role the Acoustics Expert Witness has the opportunity to be persuasive and put forward arguments to support their viewpoint to ensure the best decision is made by the inspector/arbitrator/judge. The Acoustics Expert’s ‘duty’ as an expert witness is always to the inspector/arbitrator/judge and overrides any obligation to the person or organisation that has instructed or paid them.

Planning

On 27 March 2012 PPG 24 (the technical document providing guidance to local authorities on the use of their planning powers to minimize the adverse impact of noise) was replaced by the National Planning Policy Framework. Concepts such as ‘LOAEL’ and ‘SOAEL’ were introduced to the assessment, management and control of noise via the planning system.

However, whilst these policy objectives were introduced, supporting technical advice and quantitative guidance is still largely missing and Government has advised that it does not intend to provide such technical guidance.

This has created uncertainty for developers, regulators and their advisers regarding the approach to take on the design of a development. The absence of clear quantitative guidance has increased the number of appeals on various schemes on noise grounds (an IEMA study in 2010 found that noise and ecology top the list of most assessed constraints in Environmental Statements).

Objections to various schemes arise due to complaints about construction noise impacts, increase of road/rail/airport traffic associated with the proposals (say due to the construction of a new road, new railtracks, a new airport) and the impact to a “noisy” business via the proposed development of nearby new noise sensitive receptors.

Since there is no clear relationship between sound levels (decibel levels) and the associated human reaction (mainly annoyance and sleep disturbance), and national policy on noise is therefore correctly devoid of quantitative guidance, it is common for the parties (i.e. the developer and the Local Planning Authority) to present different views on what noise impact is considered “acceptable” or “significant”, and if permission is refused, Acoustics Expert Witnesses maybe called in to provide evidence to the Planning Inspectorate in various forms during the appeal process.

Even though differences in opinion between Acoustics Expert Witnesses often occurs in relation to technical matters (i.e. the calculation methodology used, the measurement locations chosen etc), the area of planning law also sees arguments in relation to the “appropriate” level to be used in the assessment, and this issue has been greatly intensified in the last decade.

Planning law is also the area where peculiarly the Acoustics Expert Witness may provide evidence to defend a noise impact assessment at an appeal, even though it was that same Expert (in the role of Consultant) who prepared the original assessment. As such a conflict of interest may arise even though the duties of the Expert Witness do differ compared to the duties of an Expert Advisor (a consultant). Since Expert Witnesses do not have immunity any more, it is advisable that when a significant conflict of interest exists, and it is felt that the expert witness duties are compromised, the acoustician should not agree to be instructed as an expert witness and an alternative independent expert ought to be used instead.

Civil/Criminal

The two biggest areas where Acoustics Expert Witnesses appear in Civil and Criminal matters are occupational disease (Noise-induced hearing loss and hand-arm vibration syndrome) and noise nuisance. Civil law relates to a dispute between parties where a remedy is sought for harm caused;  criminal law relates to punishment for illegal activity.

Occupational Disease

The majority of the expert witness reports that I have prepared in my 20+ years career are in the realm of occupational disease and in particular for matters involving occupational noise.

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 vast majority of my instructions 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.

Apart from providing estimates of the claimant’s likely daily noise exposure and lifetime noise emission levels I also review any actions that the defendant(s) 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 I am instructed on, relevant disclosure is absent or limited. Here, I must use my 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. 

The other Acoustics related issue in occupational disease that I opine on involves use of vibrating tools and the presence of hand-arm vibration syndrome (HAVS) in employees, which is a painful and potentially disabling condition that is caused by prolonged exposure to vibration transmitted to the fingers, hands and arms. Injuries associated with vibration exposure such as HAVS and carpal tunnel syndrome (CTS) have led to a significant number of compensation claims.

Reliable published vibration data may be sufficient in most cases for the purpose of an initial risk assessment; the aim of the risk assessment is to identify a significant risk and prioritise actions necessary for employers to control exposures to as low as reasonably practicable. Similarly, in HAVS claims, the concern is not so much what the precise level of vibration exposure was, but whether there was a foreseeable risk to be managed and if so, what actions should have been and were taken to mitigate the risk and prevent disabling injury.

It is rare to undertake site visits on occupational disease matters, due to these matters being what is termed as “legacy” matters, and I find the parties in such matters to be greatly organised with relevant paperwork, meaning that I may be able to produce a Part 35 compliant report in a short time frame. Generally I find occupational disease matters relevant to criminal law to take a significant longer time compared to civil matters.

Noise Nuisance

Sound only becomes noise (often defined as "unwanted sound‟) when it exists in the wrong place or at the wrong time such that it causes or contributes to some harmful or otherwise unwanted effect, like annoyance or sleep disturbance.

Unlike many other pollutants, noise pollution depends not just on the physical aspects of the sound itself, but also the human reaction to it.

Nuisance has been described as a condition or activity that unduly interferes with the use or enjoyment of land. The law acknowledges that, in modern life, there must be an element of 'give and take' between neighbouring occupiers of land and a degree of interference must be tolerated. The reason that such cases end up in court is that the line between an annoyance that must be tolerated and an actionable nuisance is not obvious. It is for the courts to decide where such boundary lies. This is not always easy to predict. The reason that different courts can come to different conclusions is that the 'give and take' nature of the law of nuisance is essentially a balancing exercise. It is sometimes referred to as the 'reasonable user' test.

Human reaction to noise is influenced by a large number of objective and subjective factors. Perception and interpretation of these factors is highly individual and individual differences can be difficult to account for in any metric aimed at assessing the general population. As a result, analysis tends to focus on physical, easily measurable properties of sound. Subjective assessment of noise character is often neglected. The majority of guidance relates to noise that is considered benign and anonymous and does not contain specific character features. When character is considered, this tends to be limited to a simplistic, objective assessment of tonality and/or impulsivity.

Noise nuisance assessments establish whether a state of affairs exists where there are periods of intrusive noise that are unreasonable and excessive to the extent that they affect the use of enjoyment of a property in a material way. Such assessments require a broader assessment approach that includes consideration of the character of the noise, its loudness, impact of the noise on basic needs such as sleep or communication, occurrence, duration, spectral content, time of occurrence, character of the area, message imparted, variation over time, regularity/predictability, respite from the noise, how easily can the Noise be avoided, the attitude of the Defendants etc. That all these factors are deemed important for considering whether a noise constitutes a nuisance highlights the complexity of noise perception and impact.

If the Defendant is a commercial business, it has as a defence the argument of the use of Best Practicable Means, meaning that even if the Court finds that the activities amount to noise nuisance, if it also finds that Best Practicable Means are already in place, and nothing more can be reasonably done to abate the nuisance, then the nuisance may continue. In such cases, I as the Acoustics Expert Witness have to not only assist the Court in the finding of noise nuisance but also to assist the Court in determining whether Best Practicable Means have been implemented to reduce the noise to as low as reasonably possible. Under the relevant law, when noise is referenced, the same applies to vibration (say construction induced vibration, or vibration due to operating plant or from train pass bys).

There are two different types of nuisance, Common Law Nuisance and Statutory Nuisance.

Common law is law that has not been passed through parliament, it has developed through legal precedent. Action against this type of nuisance can be taken privately.

Statutory Nuisance is defined by Part Three of the 1990 Environmental Protection Act. An Environmental Health officer decides whether a particular complaint meets the definition of a Statutory Nuisance. If a Defendant wishes to appeal a decision of Statutory nuisance, then it can make representations using evidence from an Acoustics Expert Witness under criminal law legislation.

Arbitration

Another area where my services as an Acoustics Expert Witness may be required is arbitration law. Arbitration is a non-court alternative method of resolving disputes, where an arbitrator or panel of arbitrators is appointed by the parties to make a binding decision, from which there are very limited grounds of challenge. Arbitration may be either ad hoc (where the parties determine whatever rules they may consider appropriate for the arbitration) or administered (where the arbitration is conducted under the auspices of one of several arbitral organisations. My previous experience in this field has been in relation to construction disputes involving acoustics (typically an acoustics product that allegedly did not perform as intended).