Perceived Urgency in Speech Warnings

Abstract

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.

Acoustic, semantic and phonetic influences in spoken warning signal words

“…Thus speakers are able to imbue an appropriate emotion into their utterance, and listeners are able to interpret this expression accurately. Similar results are shown elsewhere (Hellier et al, 2002;Barzegar & Wogalter, 1998a, Hollander & Wogalter, 2000Weedon et al, 2000;Edworthy et al, 2000) for a single measurement of perceived urgency or arousal strength. The study reported here also shows that the related dimensions of appropriateness and believability show more or less the same effects.…”

“…Some words are perceived as being more urgent, believable and appropriate than are others. In general the effects for signal word on perceived urgency are similar to those found else where for text and spoken presentation (Barzegar & Wogalter, 1998aHollander & Wogalter, 2000;Weedon et al, 2000) and similar to those found when natural speech was used in Experiment 1. Where there are differences between natural and synthetic speech in the rank order of the words, they appear to be a result of the softness of the articulation, which is only given appropriate emphasis in natural speech.…”

“…A number of studies have shown that speakers can speak signal words in proscribed ways and that these differences in intonation are picked up by listeners. However, these studies have taken single measures of signal words, either a measure of 'arousal strength' (Barzegar & Wogalter, 1998aHollander & Wogalter, 2000;Weedon et al, 2000) or 'perceived urgency' (Edworthy et al, 1998;Hellier et al, 2002). It has been argued elsewhere (Edworthy, 1997) that these are effectively the same global measure of the seriousness with which the observer or listener takes the word when presented with it.…”

Addressing the Safety of Transportation Cyber-Physical Systems: Development and Validation of a Verbal Warning Utility Scale for Intelligent Transportation Systems

“…Since many warning characteristics may combine to creating a subjective warning utility, we reviewed warning characteristics that may influence the effectiveness of warnings. To our best knowledge, we find that the following warning characteristics could influence the warning effectiveness: Category one is regarding warning effectiveness in representing the hazard/task: Representation of Event Urgency [30][31][32], the degree to which the event urgency is represented by a warning; Time to Display [33], the degree to which a warning occurs at a favourable time; Number of Replications [34]; Distinctive Features [35], the degree to which a warning can be differentiated from other warnings in the system. Category two is regarding features relevant to the warning itself: Modality [36], the way a warning is presented; Loudness [37], the attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud; Length of the Warning, the number of words in a warning; Voice Type, whether a warning is presented with a female or male voice [38]; Voice Quality [34], the degree to which a warning can be recognized; Rate of Speech, the number of words presented in terms of time.…”

The Sound Quality of Car Horns: Designing New Representative Sounds

“…Urgencyi si nt his case conceiveda sa na uditory attribute of the sound. Signals made of bursts of harmonic pulses (after [7])a nd speech signals [15,16] were studied. The results of such experiments are mathematical relationships between perceivedurgencyand acoustical properties (the more urgent signals are high in pitch, with short transients, partials with random frequencies, and an irregular rhythm).…”