Research into the effect of hearing loss (HL) on traffic safety and mobility is limited and the empirical findings are somewhat inconsistent. HL is one of the most frequent sensory deficits in humans, leading to loss of auditory information, which may affect behavior in traffic situations and might reduce traffic safety and mobility. The prevalence of age-related HL in Europe is roughly 30% for men and 20% for women at the age of 70 years, and 55% for men and 45% for women at the age of 80 years. The prevalence of age-related HL is increasing, and as a consequence the number of road users with HL will also increase. The aim of this PhD thesis was to investigate traffic safety and mobility for individuals with HL. Three studies were conducted: 1. a questionnaire survey aimed to evaluate differences in choice of transportation that might be related to HL, 2. a driving simulator study that looked into compensatory strategies and evaluated the efficiency of a tactile signal to alert the driver, and 3. a field study to evaluate these effects in real traffic and to evaluate a navigation system with a supportive tactile signal. The results of the three studies indicate that there are effects of HL on traffic safety and mobility. The effects are relatively small and often bound to driving complexity; but, systematic and consistent in replicated studies. Differences in transportation habits related to HL include less likelihood of having a driver’s license and a higher valuing of written information, with the latter possibly prioritized before time and safety issues. Moreover, respondents with more HL were less concerned about the effects of HL, which suggests that they might be using compensatory strategies. In the experimental studies, differences in driving behavior related to HL were bound to driving conditions and occurred when the complexity of the driving task increased. There was also an effect of HL on visual behavior, indicated in the simulator and confirmed in the field study, suggesting that drivers with HL have more active visual behaviors with more frequent glances in the rear-view mirror and a general scanning of the environment before looking away from the road. A tactile signal in the driver seat was found useful in both experimental studies, both for calling for the driver’s attention and facilitating navigation using a GPS navigation device. It was concluded that there are effects of HL on both traffic safety and mobility, consistently pointing toward a generally more cautious driving behavior with the use of both compensatory and coping strategies, which suggests a difference in experienced safety. Compensatory strategies associated with HL include driving at lower speeds and using a more comprehensive visual search behavior. Coping strategies associated with HL include engaging less in distracting activities. Evaluation of the tactile signal suggests that it may make driver assistance systems more accessible, not only to drivers with HL, but to all drivers. At the same time, the systems might become more effective for all users, since visual resources can be more focused on the road, which could increase both traffic safety and mobility in general. (Author/publisher)
Abstract