Perceived Urgency in Speech Warnings

<jats:p> Two experiments are reported that investigate the effects of acoustics and semantics in verbal warnings. In the first experiment subjects rated the urgency of warning signal words spoken in different presentation styles (URGENT, NON-URGENT, MONOTONE). Significant differences in urgency ratings were found between presentation styles. Acoustic analysis revealed how acoustic parameters differed within these different presentation styles. These acoustic measurements were used to construct synthesised speech warnings that differed in urgency. They were rated in experiment 2 and the predicted differences between the urgency of the words were found. These studies indicate that urgency in natural speech is produced by alterations in a few acoustic parameters and that these alterations can easily be incorporated into synthetic speech to reproduce variations in urgency. </jats:p>