Effects of Intuitive Voice Interfaces on Driving and In-vehicle Task Performance

This paper reported results of an on-road evaluation study of three types of voice interfaces, the traditional voice system, and two intuitive voice systems with text prompts on a central display and on a cluster display respectively. The effects of voice interfaces were evaluated based on primary driving and secondary in-vehicle task performance. The in-vehicle performance was characterized by the mean task duration and mean error rates in performing in-vehicle operations. It was found that the mean task duration was the shortest in using the intuitive voice system with cluster display and drivers made more errors when using the traditional voice system relative to intuitive voice systems. The error rates were the lowest when using intuitive voice system with cluster display. The visual distraction effects were examined in terms of glance percentage to the windscreen (road ahead) and number of glances towards the central display and the cluster display. Reductions in glance percentage to the windscreen were observed when using intuitive voice interfaces, accompanied by increases in glance percentage to the prompt display. The primary driving performance in using the three voice-activation interfaces was not significantly affected compared with baseline car following only situation. It is concluded that intuitive voice interfaces are a viable enhancement to traditional voice interface whilst intuitive voice interface with cluster display has relative advantages of good task performance and minor visual distraction.