Noise and hearing loss in reindeer herders.

Air conduction hearing thresholds were examined in 512 reindeer herders (aged 18-65 years, clinically normal ears) to evaluate the prevalence of noise-induced hearing loss. The hearing thresholds at 6 kHz showed significant noise-type impairment of hearing compared with those in the ISO 7029 standard or a Finnish reference population. The subjects were exposed to noise mainly in the use of snowmobiles and chain saws: daily noise exposure ranged from 93 to 104 dB(A). The age adjusted hearing thresholds deteriorated with the total noise exposure time, especially at 3 and 4 kHz. The prevalence of significant (class IV) hearing loss was 15% and impairment of hearing was frequently found even in the younger age groups. Although the use of ear protectors seems to be increased among reindeer herders, it still appears to be insufficient, and efforts to promote their use are needed.