Hearing impairment of Indian agricultural tractor drivers

Noise is an occupational hazard affecting the health and safety of the tractor drivers. The hearing impairment of Indian tractor drivers has been assessed in the present study. Sixty healthy male subjects of similar age, height and weight were selected and divided into two groups of 30 subjects each, viz. tractor drivers with more than 10 years of driving experience and office workers as control. Audiometric testing of both the ears of the selected subjects was conducted at ten frequencies, i.e. 0.125, 0.25, 0.5, 1, 1.5, 2, 3, 4, 6 and 8 kHz. It was observed that the hearing threshold levels of office workers at measured test frequencies were less than 25 dB(A) and exceeded 25 dB(A) for tractor drivers to cause hearing handicap. Statistical analysis of the data indicated significant difference in the audiometric profile of tractor drivers compared to the office workers. The estimated average excess risk of hearing impairment of the subjects was calculated from audiometric data using five standard models; it was 0.2% and 7.1% for office workers and tractor drivers respectively. Thus it can be concluded that tractor driving significantly increased the hearing threshold levels of the drivers compared to office workers.