Effects of hearing loss shown in both driving simulator and real traffic

This paper describes two studies, one conducted in VTI driving simulator III and the other on roads in and around Linkoping city center. In both studies two groups were included, one with age related hearing loss and one control group with normal hearing. The purpose was to examine differences between the groups in driving behavior, visual behavior and also to evaluate the effectiveness and acceptance of a tactile driver assistance system The driving scenario in the simulator was a 35 km long rural road with a speed limit of 70 km/h. Twice per minute drivers were prompted by a vibration in the seat to perform a secondary task by first look at and then read back a complete sequence of four letters. On road, all participants undertook two drives of 14 km each while they performed two pre-programmed navigation tasks guiding them around two different routes. The same navigation system was used for both drives but during one drive the navigation system presented only the visual information and during the other drive there was an additional vibration in the seat to guide the driver in the right direction. Effects of Hearing Loss was seen on driving speed and on visual search behavior in both simulator and in real traffic. In the driving simulator, during secondary task and when passing a parked car, participants with HL drove 5-6 km/h slower. In real traffic, on road sections with a speed limit of 70 km/h, participants with HL drove 4 km/h slower. This more cautious driving behavior suggests that drivers with HL use compensatory strategies. The fact that corresponding results can be seen both in the simulator and on real road is interesting, on one hand for simulator validity in general but also for the opportunity to further study these issues in controlled simulator experiments.