Noise-induced hearing loss in ambulance drivers

Abstract

Noise-induced hearing loss (NIHL) is a permanent impairment of the sense of hearing caused by exposure to loud sound. Several occupations involve loud noise exposure, making occupational NIHL one of the commonest occupational illnesses worldwide. Ambulance drivers are exposed to loud noise on the job, but there is no published evidence to determine whether this might be adversely affecting their hearing. The aim of this study was to measure the hearing thresholds of local state hospital ambulance drivers to determine: (1) the prevalence of significant hearing impairment and audiometric noise induced changes, and (2) correlations between audiometric thresholds and other variables (age, duration of employment, subjective symptoms and other sources of noise exposure). It was designed as a quantitative, crosssectional, non-experimental study. All full-time ambulance drivers (n=80) were given the option to voluntarily participate. This involved data collection through a brief questionnaire followed by formal hearing assessment using pure-tone audiometry. The final cohort consisted of 38 ambulance drivers, in which the prevalence of significant hearing impairment was 2.6%. In contrast, auditory symptoms (36.8%) and notched audiograms (60.5%) were much more common. The presence of audiometric notching was found to be significantly more common in drivers who admitted to being (or having been) regularly exposed to loud noise through other recreational or occupational activities (p<0.05), but had no statistically significant correlation to age (p=0.37) or duration of employment as ambulance drivers (p=0.34).