Investigating the effect of auditory takeover request signals frequency on drivers from an acute stress perspective

Abstract

This study examines the effect of auditory displays, which are typically used as takeover signals in highly automated driving, on drivers during emergencies. Acute stress was assessed by analyzing physiological features within 10 s post-stimulation, in particular the root mean square of successive differences, raw-skin conductance, and low-frequency/high-frequency ratio. Sixteen participants were recruited to perform autopilot tasks in a simulated cockpit. Acute stress was induced using three sets of beeps with inter-pulse intervals of 0.2, 0.5, and 1 s, which serve as the auditory takeover request (TOR). The participants were required to immediately initiate vehicle takeovers and perform lane-changing maneuvers following each TOR, and their physiological, psychological, and behavioral data were acquired for analysis. The results show that the relationship between acute stress and signal frequency conforms to Stevens’ power law, thus highlighting the significance of the signal frequency with respect to acute stress. Although correlations are observed between perceived urgency and acute stress, the acute stress does not correlate significantly with the takeover parameters, such as the takeover time, information-processing time, and steering wheel speed. This study provides valuable insights into the effects of TORs on drivers in terms of acute stress, thus contributing to enhanced driving safety and guiding the design of auditory TORs.