A key factor in terms of the hearing thresholds of truck drivers is working experience. New research from Tehran University of Medical Sciences in Iran has shown working experience to have a significant contributing effect on the hearing thresholds of truck drivers in frequencies of 500, 1000, 2000 and 4000Hz.
The study examined the hearing of 500 truck drivers in one of the cities in Iran's Fars province. The hearing threshold levels of the subjects were measured in frequencies of 500Hz-8000Hz. The study showed that currently nine and 12,6% of truck drivers suffered from impaired hearing on the left and right sides respectively (with a hearing threshold level greater than 25dB, deemed the boundary of normal hearing) in the mid frequencies (500, 1000, 2000 Hz) and 45% in high frequencies of both ears (4000 and 8000 Hz). From this, the study concluded that hearing damage in professional drivers was expected to occur sooner at 4000 and 8000 Hz than at lower frequencies. Finally, it was deduced that the occupational conditions of truck drivers may have bilateral, symmetrical harmful effect on hearing threshold sense in all frequencies, but mainly at a frequency of 4000 Hz.
Education and examinations
The study concluded that the harmful conditions drivers work under need to improve. Health surveillance programs such as education and periodic medical examinations are vital for pre-diagnosing and prevention of any possible impairment. Another conclusion was the need for initiatives such as better maintenance of roads; automobile industry efforts to reduce the noise level emission of vehicles, and a reduction of the number of hours per day the drivers work.