Twelve lorry drivers participated in a field study, including in total 110 tests of a waking sound system. The system was based on a time and frequency varied sound, generated at intervals between 1 and 15 min for periods of 3-7 s. The waking effect of the sound was analysed through subjective ratings. Exposure to the sounds was correlated to improvements of the immediate as well as the long-term self-reported changes in wakefulness. The results of the study show consistently positive assessments concerning the applied waking system, both regarding the system as a measure for raised wakefulness, increased road safety and the interest in having the system installed in the vehicle. The waking sounds were in no case felt to be annoying. Analyses of the wakefulness and other factors and the interaction related to fatigue and driving are included in the investigation. (A)
Abstract