The study covered a group of 128 private farmers aged 28-65 (mean age 47.2) who had a period of occupational activity of 11-40 years (23.9 years average). The evaluation of hearing capability was based on 2 calculated values: PTA (mean from frequency: 0.5; 1; 2 and 3 kHz) and HFA (mean from 3; 4; and 6 kHz). Statistically significant differences in mean hearing loss were observed between the 2 groups in the study: farmers-control group (p < 0.001). The value of 20 dB was adopted as a criterion of the deterioration of hearing. This criterion was exceeded in 78% of farmers examined--within the range of high frequencies (HFA), and in 45 % of farmers within the range of medium frequencies (PTA). In the control group, abnormal hearing loss was noted in 17% of people only for mean HFA value. In the group of farmers a significant correlation was noted between hearing loss (PTA and HFA) and age, as well as period of occupational activity. It was statistically confirmed that the most significant decrease in hearing occurred during the age interval up to the age of 50 and during the period of occupational activity of up to 30 years. The results of the study confirmed that noise present in the agricultural environment is the primary cause of the decrease in hearing among private farmers.
PMID 12498583 - click here to show this article in PubMed