Judy Edworthy

Improving Auditory Warning Design: Relationship between Warning Sound Parameters and Perceived Urgency

This paper presents an experimental study of the effects of individual sound parameters on perceived (psychoacoustic) urgency. Experimental Series 1 showed that fundamental frequency, harmonic series, amplitude envelope shape, and delayed harmonics all have clear and consistent effects on perceived urgency. Experimental Series 2 showed that temporal and melodic parameters such as speed, rhythm, pitch range, and melodic structure also have clear and consistent effects on perceived urgency. The final experiment tested a set of 13 auditory warnings generated by an application of the earlier experimental findings. The urgency rank ordering of this warning set was predicted, and the correlation between the predicted and the obtained order was highly significant. The results of these experiments have a widespread application in the improvement of existing auditory warning systems and the design of new systems, where the psychoacoustic and psychological appropriateness of warnings could be enhanced.

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.

The effects of music tempo and loudness level on treadmill exercise.

This study examined the effects of loudness and tempo of background music on exercise performance. A total of 30 volunteers performed five 10-min exercise sessions on a treadmill. The music listened to whilst exercising was either fast/loud, fast/quiet, slow/loud, slow/quiet or absent. Measures of running speed, heart rate, perceived exertion and affect were taken. Significant effects and interactions were found for running speed and heart rate across the different music tempo and loudness levels. More positive affect was observed during the music condition in comparison to the ‘no music’ condition. No significant differences for perceived exertion were found across conditions. These results confirm that fast, loud music might be played to enhance optimal exercising, and show how loudness and tempo interact.

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.

Interval and Contour in Melody Processing

Musician subjects were required to detect interval and contour changes in transposed versions of standard melodies of 3, 5, 7, 9,11,13, and 15 notes. Subjects were significantly better at detecting contour alterations for melodies of up to 11 notes but significantly better at detecting interval alterations in the 15-note melodies. Serial position effects for 5-, 7-, and 9-note melodies showed contour to be immediately precise after transposition, whereas the ability to detect interval alterations improved as the melodies progressed. These results suggest that, on transposition, contour information is immediately precise but is lost as melody length increases. Interval information is initially less precise but is more resistant to forgetting in longer melodies. The implication of this is that contour can be encoded independently of tonal context, whereas interval information becomes more precise as a tonal framework is established. Some musical implications of the finding are discussed.

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.

Quantifying and predicting the effects of basic text display variables on the perceived urgency of warning labels: tradeoffs involving font size, border weight and colour

Design variables surrounding the presentation of signal words in warnings have been previously shown to affect performance, or variables likely to be related to performance. The present study emphasized the signal word WARNING by presenting it in red, surrounded by a red border. It was at the head of an otherwise black pesticide label that used 8-point type. A study using 24 undergraduates investigated the effect of signal-word font size (8 to 32 points), white space around the signal word (2 to 32 points), and border width (1 to 8 points) on the rated urgency of the label. A measure of the aesthetic merit of each label was also obtained from nine design students and professionals. Seven levels of each variable were used, covering the practically-useful range of each variable in the circumstances. Results showed a linear relationship between each variable and perceived urgency, with text size having the greatest effect, followed by border width. It was shown that, within the variable ranges used, the perc...

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.