Asymmetric Hearing Loss in a Helicopter Maintainer
A 41-year-old helicopter maintenance supervisor has 12 years of rotary-wing noise exposure, often 105–110 dBA for 10-hour shifts. He reports constant tinnitus and difficulty hearing speech in the hangar, especially on his right. Audiometry shows a right 4-kHz threshold of 45 dB and left of 20 dB, with a notch at 3–6 kHz. He has not worn hearing protection consistently for six months because his helmet-mounted headset does not fit well. He is safety-critical: he marshals aircraft and listens for warning calls. He has no vertigo, no ear discharge, and no recent infection. The occupational health service must decide fitness for duty, whether this is work-related, and what program changes are needed.
1. Is he fit for his current safety-critical duties?
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Not immediately, until communication and hearing protection are assessed. The asymmetric 45-dB loss at 4 kHz, constant tinnitus, and reported difficulty hearing speech in noise create a credible safety risk for marshalling aircraft and detecting warning calls. Fitness is not determined by the audiogram alone; speech-in-noise testing, aided and unaided communication checks, and a helmet-headset fit test are needed. Temporarily restrict him from high-noise areas and from duties where hearing is the primary warning channel until those assessments are complete. He may be fit for administrative or non-noise duties. If communication can be restored with a compatible headset, custom earplugs, or a communication system, he may return with conditions and periodic review. The reasoning is that occupational hearing loss is often permanent, but the operational question is whether he can reliably receive safety-critical auditory information in the actual noise environment.
2. How should work-relatedness and causation be assessed?
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Assess exposure history, dosimetry, hearing-protection use, baseline audiograms, and the pattern of loss. The 3–6-kHz notch with asymmetric right-sided loss and 12 years of high-level rotary-wing noise is consistent with occupational noise-induced hearing loss, especially with documented poor protection for six months. However, the evaluation must exclude nonoccupational causes and confounding: recreational firearms, power tools, ototoxic medications, prior ear surgery, family history, and asymmetric causes such as acoustic neuroma or middle-ear disease. A sudden asymmetry, tinnitus, or speech difficulty warrants otolaryngology review and possibly imaging if clinically indicated. Work-relatedness should be documented with exposure records and a reasoned opinion, not simply assumed from job title. The occupational health service should also check whether the helmet-headset incompatibility is a system failure affecting other workers, because that changes the prevention strategy.
3. What corrective actions should the program implement?
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The program needs engineering and administrative controls before relying on personal protection alone. Perform noise dosimetry on the supervisor’s actual tasks, reduce idle time and unnecessary running near maintenance areas, and provide quieter equipment where feasible. Fix the helmet-headset interface, fit-test hearing protectors, and provide communication-enabled protection that allows warning calls to be heard. Rotate staff out of the highest-noise tasks, enforce hearing-protection zones, and retrain on correct insertion and helmet use. Establish baseline and annual audiometric surveillance with comparison to baseline, and track threshold shifts. Document the temporary restriction and return-to-work conditions. Refer to otolaryngology if the asymmetry is unexplained or progressive. The supervisor should be counselled about tinnitus and nonoccupational noise. Finally, audit whether other maintainers have the same headset incompatibility, because a single case often signals a broader program gap.