Interpreting Audiograms for Occupational Health Practitioners

Audiometry

At the core of occupational health is ensuring workers’ safety and well-being is paramount. As such, recent revisions to L108 health surveillance guidelines demand a closer look from practitioners, particularly concerning the interpretation of surveillance audiograms for indications of Occupational Noise-Induced Hearing Loss (NIHL). This article will delve into the updated L108 and implications for occupational health practitioners.

Evolution of L108 Guidance

The Health and Safety Executive (HSE) has long emphasised the necessity of regular hearing checks, often conducted through audiometric testing, as part of suitable health surveillance for workers exposed to noise levels equal to or exceeding an eight-hour time-weighted average of 85dBA. In 2021, revisions to the HSE’s guidance document L108 introduced significant clarifications and updates, especially in reviewing audiograms for the presence of possible NIHL. This update emphasises the importance of assessing audiograms for signs of NIHL and delineates referral requirements for newly identified or progressive cases.

Evolution of L108 Guidance

The Health and Safety Executive (HSE) has long emphasised the necessity of regular hearing checks, often conducted through audiometric testing, as part of suitable health surveillance for workers exposed to noise levels equal to or exceeding an eight-hour time-weighted average of 85dBA. In 2021, revisions to the HSE’s guidance document L108 introduced significant clarifications and updates, especially in reviewing audiograms for the presence of possible NIHL. This update emphasises the importance of assessing audiograms for signs of NIHL and delineates referral requirements for newly identified or progressive cases.

Surveillance for NIHL: Unveiling Hidden Riskse

The surveillance process aims to identify individuals at risk of NIHL due to prolonged exposure to occupational noise levels exceeding 85dB LEP,d. Summation of hearing levels and observation of audiograms enable early detection of signs indicative of NIHL, such as notches in hearing thresholds. Detecting these signs at an early stage allows for timely interventions, preventing further deterioration of hearing health and mitigating potential long-term consequences. A comprehensive understanding of workplace environments and potential sources of noise exposure is essential. Practitioners should be able to assess noise levels and determine whether individuals are regularly exposed to hazardous noise levels exceeding 85dB LEP,d.

The ability to interpret audiograms accurately is paramount. Practitioners should possess expertise in identifying patterns and anomalies, including characteristic notches indicative of NIHL. One of the challenges practitioners face is defining what constitutes a “notch” in the audiogram.

Defining Notches

A notch in an audiogram refers to a significant and abrupt decrease in hearing sensitivity at specific frequencies, typically in the 3-6 kHz range. Notches are often considered indicative of noise-induced damage to the cochlea, particularly in cases of NIHL. Notches can vary in their depth, width, and location on the audiogram. While some notches may be clearly defined, others may appear subtler and require careful examination to identify.

The interpretation of notches in audiograms can be subjective, as there is no universally agreed-upon definition or criteria for what constitutes a notch. This subjectivity can lead to variability in assessments and potential discrepancies in diagnoses. Differentiating between a true notch indicative of NIHL and other audiometric features, such as high-frequency hearing loss due to aging or other factors, can be challenging.

Before embarking on surveillance audiometry as part of hearing health surveillance, practitioners must establish a clear framework to guide their actions. One critical aspect is agreeing on a definition of a notch and delineating steps to be taken upon its detection, especially in cases of uncertainty.

Practitioners may consider collaborating to develop local policies outlining a standardized definition of a notch in audiograms. This definition should be based on established criteria from regulatory bodies, such as the HSE, guidance from Society of Occupational Medicine (SOM), UK Health Conservation Association (UKHCA) and British Society of Audiology (BSA), and consider factors like notch depth, width, and location. Stakeholders, including occupational health physicians, ENT and audiologists, should engage in discussions to reach a consensus on the definition of a notch, as an action plan upon detection may require an onward referral pathway.

Significant changes in hearing thresholds may warrant classification as Category 3, necessitating referral for medical assessment. Additionally, distinguishing stable and progressive NIHL, takes into account changes from previous audiograms and the absence of other confounding factors. All of these factors require multidisciplinary input and agreement prior to undertaking surveillance. Consistency in interpretation is crucial for accurate assessment and subsequent management.

Upon Notch Detection

Clear protocols outlining steps to be taken upon detection of a notch during surveillance audiometry are needed. These protocols should address both confirmed presence of a notch and instances where uncertainty exists regarding the notch’s presence or significance.

Action plans including referral criteria are required for individuals exhibiting notches in their audiograms. These may include referral to occupational health physicians or specialists for further evaluation and management.

A multifaceted approach that encompasses risk assessment, follow-up surveillance intervals, fitness for continued exposure, and worker information, instruction and training ensures that surveillance audiometry aligns with the overarching principles of occupational health and safety.

Occupational Health Physician Review

Cases classified as Category 3 or 4 mandate referral to an occupational physician for further assessment. Referral to an Occupational Health Physician (OHP) ensures expert evaluation of audiogram findings and nuanced interpretation of NIHL indicators.

OHPs can apply specialised knowledge and tools, such as the Coles criteria, to conduct in-depth assessments beyond standard screening protocols.
OHP reviews facilitate comprehensive decision-making regarding workplace adaptations, legal obligations, and individual fitness for continued exposure to noise. By synthesising audiogram data with contextual information and occupational health expertise, OHPs provide tailored recommendations that address both individual and organisational needs.

As part of their assessment, OHPs may advise employers on strategies to reduce sound at the source, thereby mitigating the risk of further hearing damage among workers. Implementing engineering controls, such as soundproofing or machinery modifications, can significantly decrease noise levels and minimise employees’ exposure. These proactive measures not only safeguard workers’ hearing health but also contribute to creating a safer and more conducive work environment.

Specialist Referrals

Specialist referral allows for further evaluation and support from audiologists, otolaryngologists, or other relevant specialists. These professionals possess specialised diagnostic tools and expertise to conduct detailed assessments and formulate targeted interventions. Collaborating with specialists ensures a multidisciplinary approach to managing NIHL cases, fostering synergy between occupational health practitioners and clinical experts. Through shared insights and coordinated care, specialists contribute to optimised outcomes for affected individuals, enhancing overall health and well-being.

A Sound Approach to Hearing Health

In the dynamic landscape of occupational health, a sound approach to hearing health surveillance is essential. By establishing clear protocols for notch detection, referral procedures, and interdisciplinary collaboration, practitioners can navigate the complexities of interpreting audiograms with confidence. Through ongoing education, training, and adherence to best practices, the goal of preserving workers’ hearing health and well-being can be achieved. Emphasising proactive measures, such as reducing sound at the source, underscores the commitment to creating safer and healthier workplaces for all.