We know that city centre roads are busy, noisy places. But behind tightly rolled up car windows, noise levels may be barely audible, even more so when masked by air rushing past when speeding along urban main routes and motorways.

However, this is definitely not the case when sat behind the steering wheel of a monster HGV, as a new study of 500 truck drivers, recently released, highlights the very real risk of noise induced hearing loss that drivers face, daily.

A key factor determining temporary hearing loss leading to more permanent hearing damage points to truck driver’s working experience. New research carried out at Tehran University of Medical Sciences 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 hearing threshold levels of the 500 truck drivers participating in the tests were measured in frequencies of 500Hz-8000Hz.

The study showed that the truck drivers suffered from 9 per cent impaired hearing on the left side and 12.6per cent on the right side – at a hearing threshold level greater than the 25dB considered the boundary of normal hearing – in the mid frequencies (500, 1000, 2000 Hz) and 45 per cent in high frequencies of both ears (4000 and 8000 Hz).

From this, the study found that hearing damage incurred by professional drivers was expected to occur sooner at 4000 and 8000 Hz than at lower frequencies. It was concluded that the occupational conditions of truck drivers, akin to those causing industrial deafness, may have bilateral, symmetrical harmful effect on hearing threshold sense in all frequencies, but mainly at a frequency of 4000 Hz.

The study suggests that truck driver’s working conditions can be improved by implementing health screening, education and seeking hearing loss advice. Other areas of concern focus on road maintenance and reduction of both vehicle noise emissions levels and the number of working hours per day.