Hearing Loss and Driving: Does Auditory Distraction Have a Disproportionate Effect on the Hearing Impaired?

Research showing differences between the driving outcomes of hearing impaired and normally hearing individuals (such as raised road traffic accidents), proposes this has occurred due to two main reasons: (1) that sound present in the driving environment is inaudible for hearing impaired drivers, and (2) that audible sound is disproportionately distracting for the hearing impaired driver. This thesis reports on a series of experiments which investigated the latter of these proposals. A questionnaire study was used to explore driving patterns and experiences of hearing impaired individuals. Empirical studies were also conducted to investigate the effect of hearing loss on driving performance and visual attention, under auditory task conditions. Questionnaire responses suggested that hearing impaired individuals did not perceive hearing loss as problematic for driving performance. However, the self-reported hearing of respondents predicted reports of driving difficulty better than any other independent variable. A laboratory-based study hinted that extra visual task performance decrements as a result of auditory engagement occurred in hearing impaired individuals. Since these findings were in older adults, the influence of factors co-existing with hearing loss (such as cognitive decline) were questioned. These confounds were removed by presenting an auditory task subject to simulated hearing loss in a dual-task driving simulator experiment; allowing for a young, normally hearing sample, and within-subjects design. The resulting data showed no disproportionate effect of hearing loss on driving performance during the concurrent auditory task. Accordingly, distortion to sound arising from hearing loss may not be entirely responsible for the disproportionate effects of auditory distraction in hearing impaired drivers. Other factors, co-existing with hearing loss, appear to act synergistically to cause problems. Future work should investigate further the aspects of hearing loss (and co-existing factors) responsible for changes in driving outcomes, by, for instance, using a group of young hearing impaired participants.