Driving with voices: how virtual agent affects driver stress and performance

Auditory features like voice pitch and speech style significantly influence human-computer interaction, especially in driving where voice assistants provide real-time guidance. This study examined how two voice pitches (Alto and Bass) and two speech styles (Casual and Frozen) affected drivers' cognitive and emotional responses. Eighty-four participants in a driving simulator received voice reminders from an assistant with varied auditory features while stress, heart rate variability, emotions, and task performance were recorded. Cognitive load was assessed using the NASA-TLX questionnaire. Results showed that the Frozen speech style combined with Alto pitch triggered higher stress and cognitive load, while speech style had a stronger effect than pitch on emotions. These insights aid in designing user-friendly voice assistants that reduce driver stress and improve safety. Future studies should investigate long-term effects and individual auditory differences.