Safety and Usability of Speech Interfaces for In-Vehicle Tasks while Driving: A Brief Literature Review

Abstract

The report summarizes the human factors literature on the use of speech interfaces for tasks such as music selection, email processing, dialing, and destination entry while driving. A total of 15 papers were reviewed covering 15 experiments, with subject samples ranging from 4 to 48 (mode of 24). Studies were conducted using moderate fidelity simulators (4), on the road (5), using low fidelity simulations (5), and on a test track (2). The speech interfaces were true speech recognition systems (6), Wizard-of-Oz simulations (5), or unspecified (4). People generally drove at least as well, if not better (less lane variation, speed was steadier), when using speech interfaces than manual interfaces, but using a speech interface was often worse than just driving. Speech interfaces led to less workload than manual interfaces and reduced eyes-off-the-road times, all pro-safety findings. Task completion time was less with speech interfaces, but not always (as in the case of manual phone dialing). Missing from the literature were firm conclusions about how the speech/manual recommendation varies with driving workload, recognizer accuracy, and driver age.