Effects of Auditory Display Types and Acoustic Variables on Subjective Driver Assessment in a Rail Crossing Context

Highway-rail grade crossings (HRGCs) present multiple collision risks for motorists, suggesting the need for additional countermeasures to increase driver compliance. The use of in-vehicle auditory alerts (IVAAs) at HRGCs has been increasing, but there are limited standards or guidelines on how such alerts should be implemented. In the current study, we sought to investigate the effect of different auditory display variables, such as display type and acoustics, on subjective user assessments. We recruited 24 participants and asked them to rate 36 different IVAAs belonging to one of three display types (earcons—short synthetic tones, speech alerts, and hybrid alerts consisting of an earcon and speech) along 11 subjective ratings. Results showed that a hybrid alert led to better overall ratings for acceptance, safety, and semantic understanding when compared with earcon or speech alerts. Additional analyses revealed that semantic variables, such as speech order and gender, should be accounted for when designing IVAAs in an HRGC context. Hybrid IVAAs with spatial audio showed lower Urgency and Hazard level ratings. Findings of the current study can help inform the design of IVAAs for HRGCs.

Auditory Alerts and Safety with Simulated Bicycles and Motor Vehicles

Bicycling has become an increasingly popular and environmentally friendly active transportation modality for many commuters across the nation. Consequently, as ridership increases so does the rate of bicycle–motor vehicle crashes, many of which are caused by reduced bicycle visibility and driver inattention. Therefore, one effective solution to improve bicyclist safety may be through the use of an audible bicycle alarm system to alert both the driver and the rider. A study was conducted to determine whether a unique auditory alert would be effective at reducing crash rates and whether a localized alert (i.e., an alert presented from the driver’s perspective) would improve the driver’s responsiveness in avoiding a potential collision. A driving simulator study tested car horn sounds, an experimental bike alert, and no auditory alert in different potential collision scenarios to measure collision rates and other collision avoidance metrics. Findings indicated that the experimental bike alert contributed to fewer relative crashes than the horn sound and no sound on bicycles, motor vehicles were struck more frequently than bicycles, collisions were more likely to occur from the front than the sides, and collisions were more likely for drivers going straight than when making turns. Taken together, the findings suggest that an alarm designed to be specifically compatible with bicycles is more effective than auditory alerts from other sources.

The Effect of Cognitive Load on Auditory Susceptibility During Automated Driving

Objective We experimentally test the effect of cognitive load on auditory susceptibility during automated driving. Background In automated vehicles, auditory alerts are frequently used to request human intervention. To ensure safe operation, human drivers need to be susceptible to auditory information. Previous work found reduced susceptibility during manual driving and in a lesser amount during automated driving. However, in practice, drivers also perform nondriving tasks during automated driving, of which the associated cognitive load may further reduce susceptibility to auditory information. We therefore study the effect of cognitive load during automated driving on auditory susceptibility. Method Twenty-four participants were driven in a simulated automated car. Concurrently, they performed a task with two levels of cognitive load: repeat a noun or generate a verb that expresses the use of this noun. Every noun was followed by a probe stimulus to elicit a neurophysiological response: the frontal P3 (fP3), which is a known indicator for the level of auditory susceptibility. Results The fP3 was significantly lower during automated driving with cognitive load compared with without. The difficulty level of the cognitive task (repeat or generate) showed no effect. Conclusion Engaging in other tasks during automated driving decreases auditory susceptibility as indicated by a reduced fP3. Application Nondriving task can create additional cognitive load. Our study shows that performing such tasks during automated driving reduces the susceptibility for auditory alerts. This can inform designers of semi-automated vehicles (SAE levels 3 and 4), where human intervention might be needed.

Cueing Attention to a Matrix of Values on a Head-Worn Display: Four Studies with a Multiple Patient Monitoring Task

Head-worn displays (HWDs) can help clinicians monitor multiple patients by displaying multiple patients’ vital signs. We conducted four experiments exploring design features that affect how a HWD can quickly and reliably cue attention to patient deterioration. In a series of lab-based experiments, we found that a HWD could quickly and reliably cue participants’ attention with high-contrast visual highlights with two distinct levels, or with a short white flash. However, visual alerts on a HWD did not cue attention as quickly as similar alerts on a conventional screen or auditory alerts. We conclude that HWDs can quickly notify clinicians of patient deterioration when paired with a strong visual cue, but there are perceptual challenges unique to HWDs.

Adaptive Auditory Alerts for Smart In-Vehicle Interfaces

Missing a message from an in-vehicle device can range in severity from annoying at best to dangerous at worst. The in-cab auditory environment can vary spontaneously, making some volume levels too loud while rendering others too quiet. It is in the best interest of system designers, both from a safety and user experience perspective, to ensure that users are able to adequately hear alerts, and that drivers do not have to alter their gaze or attention during a visually and attentionally demanding task such as driving. To this end, we propose a system for dynamically tracking the background noise intensity level immediately prior to alert presentation in order to present an alert at an appropriate loudness. Furthermore, we evaluated the proposed system across both behavioral (accuracy and reaction time) and subjective (questionnaire results) measures. Behavioral results showed that while the proposed system increased recognition in one noise condition (background music), it also led to slower responses in two other noise conditions (windows-down and windows-up noise).

Effect of Visual and Auditory Alerts on Older Drivers’ Glances toward Latent Hazards while Turning Left at Intersections

Older drivers are known to make significantly fewer glances toward hazards that are hidden from view (latent hazards) than middle-aged drivers. This is especially true when the driver is making a left turn at an intersection at that critical point in the turn immediately after the driver enters the intersection. This has led to the development of training programs that can increase the frequency of these glances toward latent hazards at intersections. However, training programs can require time and money that many older adults may not have. Advances in machine vision and vehicle-to-vehicle communications technologies make possible the use of alerts that warn older drivers of the location of latent hazards at intersections. This driving simulator study investigates the effect of auditory and visual warning alerts on older drivers’ primary (before entering the intersection) and secondary (just after entering the intersection) glance behavior when making a left turn at an intersection. In a between-subjects design, forty older drivers navigated eight unique scenarios containing latent hazards either in the presence or in the absence of combined auditory and visual hazard warning alerts. The results showed that older drivers anticipated a significantly greater proportion of latent hazards in the presence of warning alerts both before they enter the intersection and after they enter the intersection. The results of this study suggest that a combination of auditory and visual alerts may be effective at improving older drivers’ glance behavior while making left turns at intersections.

Examining Speech-Based Auditory Alerts for Intersection Collision Warning Systems using a Driving Simulator

Collision warning systems alert drivers of potential safety hazards. Forward collision warning (FCW) systems have been widely implemented and studied. However, intersection collision warning systems (ICWS), such as intersection movement assist (IMA), are more complex. Additional studies are needed to identify the best alert for directing the driver toward the hazard. A driving simulator study with 48 participants was conducted to examine three speech-based auditory alerts (general, directional, and command) in a simulated red light running (RLR) collision scenario. The command alert that informed the drivers to brake was the most effective in reducing the number of collisions. The post-drive questionnaire showed that drivers also rated the brake alert to be best in terms of interpretation (based on the Kruskal Wallis test). This study provides insight into the performance of different types of speech-based alerts for an intersection collision warning system and can provide guidance for future studies.

Context-Sensitive Ecological Momentary Assessment: Application of User-Centered Design for Improving User Satisfaction and Engagement During Self-Report (Preprint)

BACKGROUND Ecological momentary assessment (EMA) can be a useful tool for collecting real-time behavioral data in studies of health and health behavior. However, EMA administered through mobile technology can be burdensome, and it tends to suffer from suboptimal user engagement, particularly in low health-literacy populations. OBJECTIVE This study aimed to report a case study involving the design and evaluation of a mobile EMA tool that supports context-sensitive EMA-reporting of location and social situations accompanying eating and sedentary behavior. METHODS An iterative, user-centered design process with obese, middle-aged women seeking care in a safety-net health system was used to identify the preferred format of self-report measures and the look, feel, and interaction of the mobile EMA tool. A single-arm feasibility field trial with 21 participants receiving 12 prompts each day for momentary self-reports over a 4-week period (336 total prompts per participant) was used to determine user satisfaction with interface quality and user engagement, operationalized as response rate. A second trial among 38 different participants randomized to receive or not to receive a feature designed to improve engagement was conducted. RESULTS The feasibility trial results showed high interface satisfaction and engagement, with an average response rate of 50% over 4 weeks. Qualitative feedback pointed to the need for auditory alerts. We settled on 3 alerts at 10-min intervals to accompany each EMA-reporting prompt. The second trial testing this feature showed a statistically significant increase in the response rate between participants randomized to receive repeat auditory alerts versus those who were not (60% vs 40%). CONCLUSIONS This paper reviews the design research and a set of design constraints that may be considered in the creation of mobile EMA interfaces personalized to users’ preferences. Novel aspects of the study include the involvement of low health-literacy adults in design research, the capture of data on time, place, and social context of eating and sedentary behavior, and reporting prompts tailored to an individual’s location and schedule. CLINICALTRIAL ClinicalTrials.gov NCT03083964; https://clinicaltrials.gov/ct2/show/NCT03083964