Hearing Impairment Affects Older People's Ability to Drive in the Presence of Distracters

Louise Hickson, PhD; Joanne Wood, PhD; Alex Chaparro, PhD; Philippe Lacherez, PhD; Ralph Marszalek, BPsychSci(Hons)

Disclosures

J Am Geriatr Soc. 2010;58(6):1097–1103 

In This Article

Discussion

These findings indicate that moderate to severe hearing impairment in older drivers is associated with worse driving performance in the presence of distracters, during which the deleterious effect of distracters (auditory or visual) was greater in those with moderate to severe hearing impairment than for those with normal to mild hearing impairment. Distracters are an integral part of everyday driving; therefore these findings have important practical implications. These findings suggest that older people with hearing impairment should make every effort to reduce in-vehicle distractions such as listening to the radio, conversations with passengers, looking at navigation systems, and mobile phone use.

This is the first study of older drivers that has included objective measures of hearing and an on-road assessment of driving performance, and it is the first to identify an adverse affect of hearing impairment on aspects of driving performance. Previous studies have used self-reported hearing impairment and driving, and few associations have been found. Thus, advice about the influence of hearing on driving should be based on objective measures and, in particular, on pure-tone audiometry results in the better ear, because this was the best predictor of driving performance overall in this sample.

Participants' degree of hearing impairment had the greatest effect on the driving component skill of sign recognition when driving in the presence of distracters. Performance showed the same pattern as the overall driving score, with no effect of hearing when there were no distracters and then a decline in performance with distraction. It has previously been reported that, when people are driving in complex situations, drivers appear to prioritize vehicle control tasks such as staying in their lane[27,28] while shedding other tasks like reading and naming signs.[21] This finding is also consistent with reports that a person's peripheral useful field of view is less in the presence of distracters[29] and the fact that older people have more accidents at intersections,[1] where sign recognition is critical. There was also a trend for poorer sign recognition performance when the distracter was auditory, rather than visual, and this warrants further investigation. It may be that the combination of the auditory activity of listening and adding up numbers with reading and naming signs, both of which have phonological loads to some extent, was more effortful than the combination of a visual distracter and the sign recognition task.

Overall, these findings are consistent with those from other studies of older adults with hearing impairment in which the sensory–perceptual deficit of hearing impairment negatively influences performance on cognitive tasks.[10,30] Referred to as the effortfulness hypothesis,[31] the decrease in performance on a primary task is believed to occur because the extra effort associated with listening to and understanding a degraded auditory signal deprives resources from other cognitive processes. This study, as with any study of aging, did not have the power to detect all potential interactive effects of functional status that might affect driving. Although the aim of this study was to examine the effects of hearing alone in an otherwise representative sample of older adults (who will typically have a range of cognitive, motor, and perceptual function), it might also be informative in future studies to examine whether the effects described here also interact with other areas of function, in particular mental health and cognitive impairment, which also may impose constraints on cognitive processes.

In conclusion, this study found that moderate to severe hearing impairment in older people has a negative effect on driving performance in complex situations. These findings provide further evidence of how changes in low-level sensory acuity can influence cognitive processes that support complex behaviors such as driving. The results suggest that older drivers with moderate to severe hearing impairment are at greater risk of unsafe driving in the presence of distracters, and this needs to be taken into account when designing new technologies and when providing driving advice to these individuals regarding driving situations to avoid. Knowledge of the potential interactions are of importance in an increasingly complex driving environment in which older adults are driving well into old age and auditory displays and in-vehicle devices are becoming more prevalent in vehicles.

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