Elizabeth Hellier

Improving Auditory Warning Design: Quantifying and Predicting the Effects of Different Warning Parameters on Perceived Urgency

The effects of four parameters (speed, fundamental frequency, repetition units, and inharmonicity) on perceived urgency were scaled using an application of Stevenss power law. From the exponents obtained, equal units of urgency change were calculated for three parameters. The units were combined in a set of stimuli, and the order of urgency was predicted. The obtained and predicted orders of urgency were highly correlated. The results also showed that even when equalized by psychophysical techniques, some parameters contribute more to perceived urgency than do others. This may be attributable to the different types of parameters scaled or the proportion of the usable range of each parameter that represents a unit change in urgency. The implication of the work for the design and improvement of auditory warnings is discussed.

A review of human factors principles for the design and implementation of medication safety alerts in clinical information systems

The objective of this review is to describe the implementation of human factors principles for the design of alerts in clinical information systems. First, we conduct a review of alarm systems to identify human factors principles that are employed in the design and implementation of alerts. Second, we review the medical informatics literature to provide examples of the implementation of human factors principles in current clinical information systems using alerts to provide medication decision support. Last, we suggest actionable recommendations for delivering effective clinical decision support using alerts. A review of studies from the medical informatics literature suggests that many basic human factors principles are not followed, possibly contributing to the lack of acceptance of alerts in clinical information systems. We evaluate the limitations of current alerting philosophies and provide recommendations for improving acceptance of alerts by incorporating human factors principles in their design.

Fewer but better auditory alarms will improve patient safety

Auditory warnings and alarms are used throughout the medical environment but often fall short of ideal. In some instances they can be a hindrance rather than a help to medical practice. The main reasons why alarms are less than ideal are: (1) they are used too often and people’s hearing as the primary warning sense is overused; (2) false alarm rates are often exceedingly high because trigger points are inappropriately set; and (3) their design is often poor. However, enough is now known about auditory warning design and implementation to overcome many of the traditional problems associated with them. A new draft international standard incorporates many of these measures, and increasing pressure from safety organisations such as the Joint Commission on the Accreditation of Healthcare Organisations in the USA and the National Patient Safety in the UK can help to improve the way that auditory warnings are used in medical care by implementing what is known from research into practice.

The perceived urgency of speech warnings: Semantics versus acoustics

The relationship between the semantics of words and the acoustics of the way they are spoken is explored. Actors spoke warning signal words in urgent, nonurgent and monotone style, and participants rated the urgency of the words. Results showed effects for signal word and style of presentation. Acoustic analysis showed that the urgent words were spoken at higher frequency with a broader pitch range and were louder than the nonurgent or monotone words. These acoustic differences were used to synthesize artificial versions of signal words in urgent and nonurgent formats. The urgent words were rated as more urgent than the nonurgent words, a finding attributable to their differing acoustics. Within each speaking style the words were acoustically the same, yet effects for signal word were found, suggesting that semantics is also important in urgency perception. This research has implications for the design and implementation of speech warning systems, particularly those in which urgency mapping is required.

On using psychophysical techniques to achieve urgency mapping in auditory warnings

It is well established that warning implementation should aim to achieve urgency mapping between the perceived urgency of the warning itself and the situational urgency of the condition that it indicates. This paper describes how Stevens Power Law [Psychological Review, 64, 153 181, 1957], which quantifies the relationship between objective parameters (such as the pitch of a warning) and subjective parameters (such as perceived urgency), can be applied to the design of auditory warnings to facilitate such urgency mapping. Studies that have quantified and predicted the effects of different warning parameters on perceived urgency using an application of Stevens Power Law are reported.

Considering the impact of medicine label design characteristics on patient safety.

Medication errors involving patients receiving the wrong medicines, the wrong dosages or failure to take medicines according to the prescribed schedule are a substantial threat to patient safety. In the medical domain, research evidence on the benefits of improved labelling are piecemeal and often single-product or single-manufacturer driven and often do not inform the more general process of label design. Government and other guidelines on this topic are often low level and non-specific, often failing to give evidence-based guidance. However, there is a wealth of evidence-based research findings in related areas such as food labelling, chemical labelling and more general warnings research, which can provide systematic evidence on the effects of design characteristics such as font size, colour, signal words and linguistic usage on crucial performance variables such as compliance, understandability and discriminability. This research is reviewed and its relevance to medicine labelling is presented.

On the stability of the arousal strength of warning signal words

SUMMARY Studies are reported that demonstrate the stability of scales of the arousal strength of warning signal words[ We demonstrate that these scales are not an artefact of the measurement technique employed\ nor are they in~uenced by the e}ects of experimental context[ In addition\ we generalize previous _ndings on the arousal strength of signal words to the UK population[ Separate studies revealed a high level of agreement in signal word arousal strengths derived from magnitude estimation\ category estimation\ and cross!modality matching[ In addition\ the relative arousal strengths of signal words were shown to be independent of the composition of the warning stimulus set[ These _ndings suggest that arousal strength scales of signal words are robust and that signal words can be used with con_dence to achieve hazard matching between the hazard inherent in a product:situation and the hazard implied by the associated warning[ Copyright 1999 John Wiley + Sons\ Ltd[

Speech warnings : a review

This article reviews the use and design of speech warnings in terms of ergonomic considerations. Firstly, it considers the benefits of using the auditory channel and technological approaches to producing artificial speech, Secondly, the characteristics of human and machine-generated speech are reviewed: the latter focusing on naturalness, intelligibility, rate of presentation, emotional content and quality. Thirdly, non-speech and speech warnings, and their potential uses are considered and the design of speech for warning applications. Given technological developments, greater use of the auditory channel for warnings is likely: taking into account human factors considerations should lead to better designed warnings.

What determines auditory similarity? The effect of stimulus group and methodology

Two experiments on the internal representation of auditory stimuli compared the pairwise and grouping methodologies as means of deriving similarity judgements. A total of 45 undergraduate students participated in each experiment, judging the similarity of short auditory stimuli, using one of the methodologies. The experiments support and extend Bonebrights (1996) findings, using a further 60 stimuli. Results from both methodologies highlight the importance of category information and acoustic features, such as root mean square (RMS) power and pitch, in similarity judgements. Results showed that the grouping task is a viable alternative to the pairwise task with N > 20 sounds whilst highlighting subtle differences, such as cluster tightness, between the different task results. The grouping task is more likely to yield category information as underlying similarity judgements.

Risk of Fatal Injury in Older Adult Drivers, Passengers, and Pedestrians

To compare risk of fatal injury in elderly road users (drivers, passengers, pedestrians) with that of younger age groups and to assess the contribution of elderly road users to the number of reported fatalities in the population.