The conservation of hearing in industry
The research investigated the efficiency with which industrial monitoring audiometry can increase hearing protector usage in noisy industries, and alter attitudes held by employees towards the conservation of hearing. A controlled study was conducted which embraced approximately 2000 employees from 20 plants on a single site. Use was made of specially developed attitude questionnaires to measure attitude changes caused by the experimental treatments. Hearing protector usage was also monitored. The results showed strongly that industrial audiometry is a powerful method by which attitudes towards hearing conservation can be changed, and the usage of hearing protection increased. It is recommended that monitoring audiometry should be awarded a stronger role in a hearing conservation programme than is presently intended under the proposals for United Kingdom legislation on industrial noise. The results of the research work are also used to specify the optimum balance between the relative strengths of the components of audiometry and education in a programme of hearing conservation. A database of 954 audiograms obtained during the study was used to form conclusions on the manner in which industrial monitoring audiometry should be conducted. This database was also used to demonstrate the relationship between poor hearing thresholds and auditory problems experienced when using hearing protection in noise. Additionally it was shown that the link suggested in the literature to exist between eye colour and susceptibility to noise induced hearing loss had no basis in fact. Finally, the discomfort of earmuffs was shown to be a strong counterforce mitigating against any increase in hearing protector usage, and a specification for a comfortable earmuff was therefore developed.