Nature and Time of Onset of Auditory Deviations as a Result of Exposure to Occupational Noise

Abstract

Professional bus drivers, particularly those operating front-engine vehicles, are frequently exposed to high levels of occupational noise, which increases their risk of noise-induced auditory damage. Extended exposure can damage the cochlear hair cells or bring in subclinical changes in the form of cochlear synaptopathy. Cochlear synaptopathy is disruption of synapses between inner hair cells and afferent auditory nerve fibres. These alterations can impact auditory functions at both peripheral and central levels. Although past research has documented the adverse effects of noise on hearing thresholds, speech identification, temporal processing, and auditory functions like otoacoustic emissions (OAEs) and auditory brainstem responses (ABRs), the findings have been inconsistent. Importantly, the timeline of the onset of auditory deviations remains poorly understood. This study investigated the effects of occupational noise exposure on behavioral and physiological measures of auditory function in bus drivers, and examined the relationship between duration of noise exposure and onset of auditory deviations.