Publication

Purpose To compare the effect of cognitive workload in individuals with and without hearing loss, respectively, in driving situations with varying degree of complexity. Methods 24 participants with moderate hearing loss (HL) and 24 with normal hearing (NH) experienced three different driving conditions: Baseline driving; Critical events with a need to act fast; and a Parked car event with the possibility to adapt the workload to the situation. Additionally, a Secondary task (observation and recalling of 4 visually displayed letters) was present during the drive, with two levels of difficulty in terms of load on the phonological loop. A tactile signal, presented by means of a vibration in the seat, was used to announce the Secondary task and thereby simultaneously evaluated in terms of effectiveness when calling for driver attention. Objective driver behavior measures (M and SD of driving speed, M and SD of lateral position, time to line crossing) were accompanied by subjective ratings during and after the test drive. Results HL had no effect on driving behavior at Baseline driving, where no events occurred. Both during Secondary task and at the Parked car event HL was associated with decreased mean driving speed compared to baseline driving. The effect of HL on the Secondary task performance, both at Baseline driving and at the lower Difficulty Level at Critical events, was more skipped letters and fewer correctly recalled letters. At Critical events, task difficulty affected participants with HL more. Participants were generally positive to use vibrations in the seat as a means for announcing the Secondary task. Conclusions Differences in terms of driving behavior and task performance related to HL appear when the driving complexity exceeds Baseline driving either in the driving task, Secondary task or a combination of both. This leads to a more cautious driving behavior with a decreased mean driving speed and less focus on the Secondary task, which could be a way of compensating for the increasing driving complexity. Seat vibration was found to be a feasible way to alert drivers with or without HL.