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.     

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.     

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.     

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.     

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.     

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.     

Learning associations between natural groups of input and output with a neurofuzzy structure

A new modeling approach that finds the associations between natural groups of input and output is proposed. In the new method, input and output are clustered separately by means of Fuzzy C-Means (FCM) algorithm. Then, the learning algorithm identifies the fuzzy rules by relating the resulting fuzzy sets in input and output spaces by using a neurofuzzy architecture. A modified version of classical simulated annealing algorithm is used in order to identify the relative weights of system input variables. The proposed approach is applied to a highly nonlinear function and successful result is achieved.     

A comparison of tactile, visual, and auditory warnings for rear-end collision prevention in simulated driving

OBJECTIVE: This study examined the effectiveness of rear-end collision warnings presented in different sensory modalities as a function of warning timing in a driving simulator. BACKGROUND: The proliferation of in-vehicle information and entertainment systems threatens driver attention and may increase the risk of rear-end collisions. Collision warning systems have been shown to improve inattentive and/or distracted driver response time (RT) in rear-end collision situations. However, most previous rear-end collision warning research has not directly compared auditory, visual, and tactile warnings. METHOD: Sixteen participants in a fixed-base driving simulator experienced four warning conditions: no warning, visual, auditory, and tactile. The warnings activated when the time-to-collision (TTC) reached a critical threshold of 3.0 or 5.0 s. Driver RT was captured from a warning below critical threshold to brake initiation. RESULTS: Drivers with a tactile warning had the shortest mean RT. Drivers with a tactile warning had significantly shorter RT than drivers without a warning and had a significant advantage over drivers with visual warnings. CONCLUSION: Tactile warnings show promise as effective rear-end collision warnings. APPLICATION: The results of this study can be applied to the future design and evaluation of automotive warnings designed to reduce rear-end collisions.     

Temporal symmetry in primary auditory cortex: implications for cortical connectivity

Neurons in primary auditory cortex (AI) in the ferret (Mustela putorius) that are well described by their spectrotemporal response field (STRF) are found also to have a distinctive property that we call temporal symmetry. For temporally symmetric neurons, every temporal cross-section of the STRF (impulse response) is given by the same function of time, except for a scaling and a Hilbert rotation. This property held in 85% of neurons (123 out of 145) recorded from awake animals and in 96% of neurons (70 out of 73) recorded from anesthetized animals. This property of temporal symmetry is highly constraining for possible models of functional neural connectivity within and into AI. We find that the simplest models of functional thalamic input, from the ventral medial geniculate body (MGB), into the entry layers of AI are ruled out because they are incompatible with the constraints of the observed temporal symmetry. This is also the case for the simplest models of functional intracortical connectivity. Plausible models that do generate temporal symmetry, from both thalamic and intracortical inputs, are presented. In particular, we propose that two specific characteristics of the thalamocortical interface may be responsible. The first is a temporal mismatch between the fast dynamics of the thalamus and the slow responses of the cortex. The second is that all thalamic inputs into a cortical module (or a cluster of cells) must be restricted to one point of entry (or one cell in the cluster). This latter property implies a lack of correlated horizontal interactions across cortical modules during the STRF measurements. The implications of these insights in the auditory system, and comparisons with similar properties in the visual system, are explored.