Abstract
Voice agent systems are deployed widely in various devices such as mobile phones, smart speakers, televisions, and refrigerators. Although the market for voice agent systems has expanded significantly and the systems themselves are becoming intelligent, their usability remains limited. This study provides general and practical guidelines for voice interaction to help VUI (Voice User Interface) designers and developers in the process of designing voice agent systems. The current guidelines only offer generic information for VUI designers, as they only provide the static aspect of voice interaction rather than consider the entire conversation flow. Studies on designing voice interaction systems have shown that VUI designers and developers need more guidance. The new interaction guidelines were developed based on users' cognitive strategy in the course of using voice agent systems. We proposed and evaluated 12 practical voice interaction design guidelines for conversational voice agent systems. To evaluate the guidelines, we recruited 60 experts with different levels of voice interaction. Participants evaluated the usefulness of the guidelines and provided insightful opinions on them.