Use of auditory icons as emergency warnings: evaluation within a vehicle collision avoidance application

In the context of emergency warnings, auditory icons, which convey information about system events by analogy with everyday events, have the potential to be understood more quickly and easily than abstract sounds. To test this proposal, an experiment was carried out to evaluate the use of auditory icons for an invehicle collision avoidance application. Two icons, the sounds of a car horn and of skidding tyres, were compared with two conventional warnings, a simple tone and a voice saying ‘ahead’. Participants sat in an experimental vehicle with a road scene projected ahead, and they were required to brake in response to on-screen collision situations and their accompanying warning sounds. The auditory icons produced significantly faster reaction times than the conventional warnings, but suffered from more inappropriate responses, where drivers reacted with a brake press to a non-collision situation. The findings are explained relative to the perceived urgency and inherent meaning of each sound. It is argued that optimal warnings could be achieved by adjusting certain sound attributes of auditory icons, as part of a structured, user-centred design and evaluation procedure.     

Use of auditory icons as emergency warnings: evaluation within a vehicle collision avoidance application.

In the context of emergency warnings, auditory icons, which convey information about system events by analogy with everyday events, have the potential to be understood more quickly and easily than abstract sounds. To test this proposal, an experiment was carried out to evaluate the use of auditory icons for an in-vehicle collision avoidance application. Two icons, the sounds of a car horn and of skidding tyres, were compared with two conventional warnings, a simple tone and a voice saying 'ahead'. Participants sat in an experimental vehicle with a road scene projected ahead, and they were required to brake in response to on-screen collision situations and their accompanying warning sounds. The auditory icons produced significantly faster reaction times than the conventional warnings, but suffered from more inappropriate responses, where drivers reacted with a brake press to a non-collision situation. The findings are explained relative to the perceived urgency and inherent meaning of each sound. It is argued that optimal warnings could be achieved by adjusting certain sound attributes of auditory icons, as part of a structured, user-centred design and evaluation procedure.     

The design and implementation of non-verbal auditory warnings

There are many common problems in the use of non-verbal auditory warnings in the working environment. They are often too loud, too numerous, and they are frequently confusing. These problems have a range of consequences, many of them serious. However, there now exist a number of guidelines and sets of experimental data that address these problems and provide fairly comprehensive solutions. In this article the underlying problems are highlighted, and the guidelines and research that have addressed the central issues of correct loudness levels and psychological appropriateness, particularly warning confusion and 'urgency mapping', are reviewed and evaluated. It is argued that a proper ergonomics approach to auditory warning design and implementation is not a luxury, but a necessity. A number of projects in which advanced, ergonomic auditory warning systems have been developed are described in detail, and some new research questions are proposed.     

A new class of auditory warning signals for complex systems: auditory icons

This simulator-based study examined conventional auditory warnings (tonal, nonverbal sounds) and auditory icons (representational, nonverbal sounds), alone and in combination with a dash-mounted visual display, to present information about impending collision situations to commercial motor vehicle operators. Brake response times were measured for impending front-to-rear collision scenarios under 6 display configurations, 2 vehicle speeds, and 2 levels of headway. Accident occurrence was measured for impending side collision scenarios under 2 vehicle speeds, 2 levels of visual workload, 2 auditory displays, absence/presence of mirrors, and absence/presence of a dash-mounted iconic visual display. For both front-to-rear and side collision scenarios, auditory icons elicited significantly improved driver performance over conventional auditory warnings. Driver performance improved when collision warning information was presented through multiple modalities. Brake response times were significantly faster for impending front-to-rear collision scenarios using the longer headway condition. The presence of mirrors significantly reduced the number of accidents for impending side collision scenarios. Subjective preference data indicated that participants preferred multimodal displays over single-modality displays. Actual or potential applications for this research include auditory displays and warnings, information presentation, and the development of alternative user interfaces.     

Cough once for danger: icons versus abstract warnings as informative alerts in civil aviation

OBJECTIVE: An experiment investigated the efficacy of auditory icons as warning signals in an aviation context. BACKGROUND: Iconic signals, such as a cough to signal dangerous levels of carbon monoxide, convey information about the nature of an incident and alert the operator that there is a problem, whereas signals that are arbitrarily associated with a critical incident provide relatively less information. Warning recognition speed and accuracy are likely to be influenced by modality of presentation (visual, auditory, auditory + visual) and task demand (low, high). METHODS: The 172 participants completed a computer-based training session and test task that involved responding to abstract or iconic auditory (1 s), visual, or auditory + visual warnings associated with seven critical incidents while performing low- and high-demand concurrent tasks. RESULTS: Significantly fewer training trials were required to learn iconic warnings than abstract warnings. An advantage for iconic warnings persisted into the test phase, evident most consistently as greater warning recognition accuracy. The effect was observed in both high- and low-demand conditions. Auditory abstract warnings, in particular, elicited slow reaction times and poor accuracy. CONCLUSION: Associations between a small number of meaningful environmental sounds and critical incidents can be learned with ease relative to more abstract associations, although training is required and response times are relatively slow. APPLICATION: Sets of distinctive auditory iconic warnings can be designed to alert and inform pilots about non-time-pressured events. Potential applications of language-neutral icons as informative warnings include civil, commercial, and defense aircraft.     

Perception-action icons: an interface design strategy for intermediate domains

OBJECTIVE: A prototype interface was developed to support decision making during tactical operations; a laboratory experiment was conducted to evaluate the capability of this interface to support a critical activity (i.e., obtaining the status of friendly combat resources). BACKGROUND: Effective interface design strategies have been developed for domains that have primarily law-driven (e.g., process control) or intent-driven (e.g., information retrieval) constraints. However, design strategies for intermediate domains in which both types of constraints are equally critical, such as military command and control, have not been explored as extensively. The principles of direct perception, direct manipulation, and perception-action loops were used to develop a hybrid interface design strategy ("perception-action icons") that was incorporated into the prototype interface. METHODS: A qualitative tactical simulation and an alternative interface (an experimental version of an existing U.S. Army interface) were developed. Participants used both interfaces to provide estimates of friendly combat resources for three different categories of information at three different echelon levels. RESULTS: The results were unequivocal, indicating that the interface with perception-action icons produced significantly better performance. CONCLUSION: The perception-action icon design strategy was very effective in this experimental context. The potential for this design strategy to be useful for other intermediate domains is explored. APPLICATION: Actual or potential applications of this research include both specific interface design strategies for military command and control and general interface design principles for intermediate work domains.     

Learning auditory warnings: The effects of sound type, verbal labelling and imagery on the identification of alarm sounds

This study looks at the effect of sound type, training cue and cue source on people's ability to learn and retain a set of twelve warning-type sounds. Each participant was required to learn and retain each of the twelve sounds using one of four learning methods. One group was required to learn the sounds according to verbal labels given to them by the experimenter; a second group generated their own verbal labels; a third group was required to learn the sounds using graphic images (the waveform of the sound) given to them by the experimenter; and the fourth group was allowed to generate their own graphic images. Three classes of sound were tested: real, environmental sounds, semi-abstract monitoring-type sounds, and abstract sounds already used as hospital warnings. The results show that the verbal labels worked better than graphic images, but only when these were given by the experimenter. When participants generated their own cues, performance was equally good in both graphic and verbal conditions. Across the sounds, it was found that real sounds were easier to learn than the other two groups, although this effect again disappeared when participants were allowed to generate their own cues. The implications for auditory warning design and training are discussed within a broader theoretical and practical context.

Relevance to industry

This paper shows that the difficulty with which alarm-type sounds can be learned depends not only on the type of sounds to be learned, but the way in which they are learnt. Apparent advantages to using environmental sounds and verbal labels disappears as soon as participants are allowed to generate their own learning aids.     

Iterative process of design and evaluation of icons for interactive TV menu

This paper shows an iterative process of design and evaluation of icons for future interactive TV services. In doing the RNRT (French National Network of Research in Telecommunications) iTV project, we tried to generate icons easy to identify, associate and memorise for 32 categories and services of our iTV system.

Through an iterative process, the Multiple Index Approach was applied until an acceptable icon set was achieved. In addition to existing evaluation criteria such as the intuitiveness, associativeness, preference and suitability with subjective certainty of users, we emphasised the importance of the learnability measured by recall tests.

As a conclusion, we propose a methodology of icon design and evaluation for information appliances that integrate unfamiliar features with common users.     

Impact of speech presentation level on cognitive task performance: implications for auditory display design

Speech displays and verbal response technologies are increasingly being used in complex, high workload environments that require the simultaneous performance of visual and manual tasks. Examples of such environments include the flight decks of modern aircraft, advanced transport telematics systems providing invehicle route guidance and navigational information and mobile communication equipment in emergency and public safety vehicles. Previous research has established an optimum range for speech intelligibility. However, the potential for variations in presentation levels within this range to affect attentional resources and cognitive processing of speech material has not been examined previously. Results of the current experimental investigation demonstrate that as presentation level increases within this 'optimum' range, participants in high workload situations make fewer sentence-processing errors and generally respond faster. Processing errors were more sensitive to changes in presentation level than were measures of reaction time. Implications of these findings are discussed in terms of their application for the design of speech communications displays in complex multi-task environments.     

Impact of speech presentation level on cognitive task performance: implications for auditory display design

Speech displays and verbal response technologies are increasingly being used in complex, high workload environments that require the simultaneous performance of visual and manual tasks. Examples of such environments include the flight decks of modern aircraft, advanced transport telematics systems providing in-vehicle route guidance and navigational information and mobile communication equipment in emergency and public safety vehicles. Previous research has established an optimum range for speech intelligibility. However, the potential for variations in presentation levels within this range to affect attentional resources and cognitive processing of speech material has not been examined previously. Results of the current experimental investigation demonstrate that as presentation level increases within this ‘optimum’ range, participants in high workload situations make fewer sentence-processing errors and generally respond faster. Processing errors were more sensitive to changes in presentation level than were measures of reaction time. Implications of these findings are discussed in terms of their application for the design of speech communications displays in complex multi-task environments.     

Iterative process of design and evaluation of icons for interactive TV menu

This paper shows an iterative process of design and evaluation of icons for future interactive TV services. In doing the RNRT (French National Network of Research in Telecommunications) iTV project, we tried to generate icons easy to identify, associate and memorise for 32 categories and services of our iTV system.

Through an iterative process, the Multiple Index Approach was applied until an acceptable icon set was achieved. In addition to existing evaluation criteria such as the intuitiveness, associativeness, preference and suitability with subjective certainty of users, we emphasised the importance of the learnability measured by recall tests.

As a conclusion, we propose a methodology of icon design and evaluation for information appliances that integrate unfamiliar features with common users.     

Spatial S–R compatibility of visual and auditory signals: implications for human–machine interface design

This study investigated spatial stimulus–response (S–R) compatibility for visual and auditory signals presented on longitudinally and transversely oriented axes. The objective was to establish data in order to make ergonomics recommendations for multi-sensory interface design in control consoles. The results showed strong stimulus–response compatibility effects. Relatively faster reaction times (RTs) and lower error percentages (EPs) were found for the compatible S–R conditions than for the incompatible conditions. Other than the main S–R compatibility effect, a stimulus–hand (S–H) compatibility effect was also found when there was no clear stimulus–response compatibility. Responses made to visual signals were faster than those to auditory signal, suggesting that the processing of visual signals dominated processing of auditory ones. Response speed increased and accuracy decreased with the adoption of crossed hand posture. Response speed decreased with the length of the warning time interval. The findings in this experiment were translated into practical ergonomics recommendations for signal–response layout, stimulus–hand layout, hand condition, warning time interval, and methods of presenting visual and auditory signals. These recommendations were made with a view to improving control console design in order to enhance operator and overall system performance.     

The semantic associations of acoustic parameters commonly used in the design of auditory information and warning signals

Two experiments are described in which the effects of acoustic parameters, and changes in those acoustic parameters, on the salience of 42 pre-selected adjectives are explored. In experiment 1 four sets of seven stimuli each varying only along one of the four acoustic parameters pitch, speed, inharmonicity and rhythm were scaled along the 42 adjectives. Parameter-adjective associations showing significant effects both in terms of consistency (Kendall's W') and in linear mapping (regression) numbered 7 for pitch, 3 for speed, 2 for inharmonicity and 1 for rhythm. Three of the four parameters produced significant levels of both consistency and linear mapping for the adjective ‘urgent’. In the second experiment, the overall meaning of complete within-parameter stimulus sets were explored and many differences both within and between parameters and adjectives were found. The results were used to design five trend monitoring sounds for helicopter flight, three of which are described in detail in this paper.     

Using technology to facilitate the design and delivery of warnings

This paper describes several ways in which new technologies can assist in the design and delivery of warnings. There are four discussion points: (1) current product information can be delivered via the Internet; (2) computer software and hardware are available to assist in the design, construction, and production of visual and auditory warnings; (3) various detection devices can be used to recognize instances in which warnings might be delivered; and (4) a warning presentation can be modified to fit conditions and persons. Implications, example applications and future prospects of these points are described.     

Integrating multiple information sources: using redundancy in the design of warnings

The ability to present high priority warning information in both the auditory and visual modalities simultaneously has required consideration to be given to their integration. This paper describes an experiment that examined whether performance gains could be achieved by the presentation of up to four sources of concurrent, congruent information, within the applied setting of aircraft Missile Approach Warnings (MAW). It was found that four sources of information produced significantly faster responses than three sources (p<0-01). Three sources of information produced significantly faster responses than two sources (p<001) of information. Two sources of information, in turn, produced significantly faster responses ( p <001) than single sources. The implications of these results for the design of time-critical warning systems are discussed.     

Interacting with VDL-based structured icons on crisis map for emergency coordination: Interactive design and experimental demonstration

Accurate and timely information sharing among multiple participants is one of the crucial factors for collaboration in crisis management. The icon-based map was frequently applied as an effective means for crisis interaction and collaboration. However, former studies only regarded the icons as supplementary visualization components during the whole crisis collaboration process. In this paper, the concept of a structured-icon-relied interactive method was proposed to directly integrate all kinds of crisis and coordination information through icons on the crisis map. Moreover, structured icons are supposed to explicitly show the correlation among crisis information and to improve the interactive experience of information search. The effectiveness of this interactive method was verified by a controlled experiment with three sub-tasks for simulated crisis rescue. The results of the experiment showed that the design of the crisis map based on structured icons had a positive impact on collaborative decision-making and crisis interaction. The dynamic characteristics of the structured icon could represent the temporal and spatial attributes of crisis information and enhance users’ crisis coordination ability. The study aims to enrich the theory of crisis information visualization and interaction based on structured iconic representation. In practice, this research could optimize the design of a crisis collaboration system based on the icon as well as the interaction between people, crisis information, and collaborative system, which in turn provides accurate and timely rescue decisions.     

Study on semantic-entity relevance of industrial icons and generation of metaphor design

The intelligent transformation of the manufacturing industry is accompanied by the visualization of industrial information, and the semantic expression of industrial icons plays a crucial role in improving operators' cognitive performance. Taking the production process of a battery production line as the research object, we studied the semantics-entity relevance of industrial icons based on the concepts of “signifier” and “signified” in metaphorical cognition as well as “topic” and “vehicle.” On this basis, we designed the icons of eight process stations (precleaning, diffusion, coating, screen printing, power testing, etc.) of the battery production line using the metaphor design method. The experimental results show that the icons complying with the law of semantic cognition have high search efficiency. It is concluded that the industrial icons should be designed according to the relevance between functional semantics and entity specific to each production process and that applying such carefully designed industrial icons to industrial information visualization will effectively improve the cognitive performance of operators.     

Effects of the aesthetic design of icons on app downloads: evidence from an android market

With the rapid development of the mobile app market, understanding the determinants of mobile app success has become vital to researchers and mobile app developers. Extant research on mobile applications primarily focused on the numerical and textual attributes of apps. Minimal attention has been provided to how the visual attributes of apps affect the download behavior of users. Among the features of app “appearance”, this study focuses on the effects of app icon on demand. With aesthetic product and interface design theories, we analyze icons from three aspects, namely, color, complexity, and symmetry, through image processing. Using a dataset collected from one of the largest Chinese Android websites, we find that icon appearance influences the download behavior of users. Particularly, apps with icons featuring higher colorfulness, proper complexity, and slight asymmetry lead to more downloads. These findings can help developers design their apps.     

The use of icons and labels in an end user application program: An empirical study of learning and retention

This research compared the learning of an application program whose interface was implemented using buttons with text labels, icons, or a fully redundant combination of icons and text labels. The objective was to: 1) evaluate the success of novice computer users in initially learning to use the application and in later use in a delayed session and 2) measure users' attitudes toward the application. Each session was divided into four blocks, and performance in the blocks was measured in terms of correctness of the tasks performed, time to perform tasks, and number of times the help facility was accessed. In addition, at the end of each session the participants' perceptions of the ease of use and usefulness of the software were measured. The results showed that in the first session performance was best on the label-only and icon-label interfaces. Performance on the icon-only interface was much poorer in session 1, particularly in terms of time and help references, but improved in session 2 to the point where it approached the performance on the other interfaces. Retention of skill between the initial and the delayed session was worse for the icon-only interface, but the effect was short-lived. Perceptions of ease of use were consistently better for the icon-label interface than for the other two interfaces. Perceptions of usefulness were higher for the icon-only and icon-label interfaces than for the label-only interface in the first session. Perceptions of usefulness became more positive for the icon-only group in the delayed session, but did not change for the other groups.