The theory makes sense: Workers with hearing loss are at greater risk of occupational injury because they are less likely to be able to hear sounds that would indicate a hazard or warning signals. But is this actually true?
Researchers at Yale studied 8,818 production and maintenance workers at an aluminum manufacturing plant over the course of six years.
Acute injury risk increased 25% among workers with a history of tinnitus combined with high-frequency hearing loss. Low-frequency hearing loss may be associated with a minor increase in risk for less serious injuries. There was no link found between asymmetrical hearing (more hearing loss on one side than the other) and increased injury risk. However, the smaller number of employees with asymmetrical hearing may have created insufficient data to determine a link.
The researchers conclude:
“These results provide evidence that tinnitus, combined with high-frequency hearing loss, may pose an important safety threat to workers, especially those who work in high-noise exposed environments. These at risk workers may require careful examination of their communication and hearing protection needs.”
How big in the impact? Tinnitus affects an estimated 12-15% of the general population in the U.S. Likelihood to experience tinnitus increases with age: More than a third of the population over 65 has it.
In this study:
- 16% had a history of tinnitus
- 12% had a history of tinnitus combined with other hearing loss, and
- 5% had asymmetrical hearing.
And here’s a complicating factor: Anecdotal reports from tinnitus sufferers indicate using hearing protection may increase the magnitude of tinnitus.
While that wasn’t proven in the study, it’s one more potential reason for another conclusion the study reached: Reducing noise exposure should be attempted first through engineering controls. (And of course the usual hierarchy for reducing hazards would make administrative controls the second preferred method, followed last by using hearing protection.)
The study (Does tinnitus, hearing asymmetry, or hearing loss predispose to occupational injury risk?) was published in the International Journal of Audiology.