Effects of Auditory Stimuli and Verbal Communications on Drivers' Situation Awareness in Partially Automated Driving

In driving automation systems with Level 2 Driving Automation, as defined by the Society of Automotive Engineers (SAE), it is necessary for the driver to monitor the system and surrounding conditions for a long time, even in a monotonous driving scene. Such a driving scene may increase the driver's drowsiness. Moreover, the driver may perform actions that are not related to driving due to driver boredom. Therefore, it is important to identify ways to improve drivers' situation awareness. In this study, we conducted a driving simulator experiment focusing on the auditory stimuli and verbal communications as methods to gain situation awareness during partially automated driving. The effects of two conditions, namely, listening to music and talking with a passenger, were evaluated quantitatively. The results showed that talking with a passenger was effective in reducing driver fatigue from driving for a long time as compared with the effect of driving when listening to music, and without auditory stimulus. However, the distinct effectiveness of auditory stimuli was merely observed by analyses of driving performance. In other words, these findings indicate that auditory stimuli are insufficient to improve driver situation awareness during automated driving.