Noise-induced Hearing Loss

Department of Occupational and Environmental Health

Noise Induced Hearing Loss in the Shipbuilding Industry


Noise is a major occupational health problem worldwide. However, there are still unresolved debates on the issue of noise-induced hearing loss.

This study has looked at the effects of long term noise exposure on everyday life amongst workers in a shipbuilding factory. Exposure was determined by environmental noise level measurements, using established formulae to calculate cumulative lifetime exposure.

Outcome measures of noise induced hearing loss was measured by the use of pure tone audiometry. A significant percentage of the workers revealed noise induced hearing loss.
The most sensitive indicator of hearing loss was 4000 Hz, which showed a positive relationship to symptomatology. However, no significant relationship was found between lifetime exposure to noise and hearing loss, nor lifetime exposure and symptoms. Our study raised some important methodological issues in noise exposure.

In conclusion, we recommend that in compensating workers consideration should be given to using the higher frequencies in hearing impairment calculations. The level of 85 dB should not be treated as a health based exposure limit, and strict hearing conservation programmes are necessary even at this noise exposure.

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