Unprotected noise exposure in occupational settings may cause hearing damage such as tinnitus or hearing loss. Hearing loss can be disabling and lead to communication problems and social withdrawal.

Previous studies on the association between occupation and hearing loss have typically been small or only considered a single occupation or work site.

– To our knowledge, this is the first large population study that both quantifies the long-term hearing decline and investigates how this change differs between occupations, says lead author and research fellow Ina Molaug.

Building frame and craft workers most at risk

The study contributes with new knowledge about associations between occupation and hearing decline. It also gives an overview of the present situation in Norway.

The results show a larger long-time hearing decline among building frame workers and craft and related trades workers, compared to clerks (reference group).

However, Molaug states, the overall differences in hearing decline between occupations is modest. This may indicate that the preventive measures implemented in Norway over the last few decades have been successful.

Measures should be continued

In general, hearing has improved in the Norwegian population, which is partially due to less occupational noise exposure.

– We believe that the findings in our study could be due to effective preventive measures to reduce noise in Norwegian workplaces, and such measures should therefore be continued, Molaug states.

She adds that updated knowledge on the association between occupation and hearing decline may help workers, employers, occupational health services and policy makers understand which workers have an increased risk.

– Such understandings enable the design of more targeted efforts to prevent hearing decline in the future, she says.

Findings on long-term exposure to noise

In another, recently published study, Molaug and colleagues studied the relationship between occupational noise exposure and hearing decline over 20 years.

Here, the researchers assessed noise exposure based on both self-reported data and a Job Exposure Matrix (JEM), which is a tool for characterizing exposure to potential health hazards in various occupations.

– In this study we found an association between JEM-based noise exposure and increased 20-year hearing decline among men. Contrary to expectations, the associations were weaker among younger workers. This might indicate that there is a latency period before we can measure the effects of noise exposure, Molaug explains.

About the studies

In both these studies, the researchers have used data from the The Trøndelag Health Study (HUNT) and Statistics Norway.

The Trøndelag Health Study is a population-based health study performed in the Norwegian county of Nord-Trøndelag. HUNT is considered one of the most extensive cohort studies ever and has been conducted four times (HUNT1-4) since 1984. HUNT2 Hearing (1996–1998) and HUNT4 Hearing (2017–2019) were part of HUNT2 and HUNT4, respectively.