Synthesized Warning Messages: Effects of an Alerting Cue in Single- and Multiple-Function Voice Synthesis Systems

Abstract

The present study examined the effectiveness of preceding synthesized voice warning messages with an alerting cue as a function of the amount of information presented by the voice synthesizer and the workload level in the primary task. Subjects performed a simplified air traffic control task in which they were required to monitor two visual displays and to enter commands via a standard keyboard. Emergency messages were always presented by phoneme-based synthesized speech. However, the presence of an alerting cue (light and tone) prior to emergency messages and the presentation mode of noncritical messages (visual or auditory) were varied experimentally. When synthesized speech was used only for emergency messages, the presence of an alerting cue lengthened the response time to the message. However, when computer-generated speech was used for multiple functions, more emergency messages were detected when an alerting cue was used.