Auditory Alarms Research Articles

Musical timbre with varied amplitude envelope improves efficacy in auditory alarms

Current alarm standards used in safety critical environments (e.g., medical alarms used in hospitals) suffer from a myriad of complications with detectability, annoyance, and alarm fatigue affecting the wellbeing of patients and staff. To a large extent, these are based on the same simplistic, temporally invariant tones. Here we explore how insights from the acoustic properties of the musical triangle can aid in detection, reducing overall levels hence reducing annoyance ratings. Two tones are used, (1) a standard tone similar to those used in current medical devices, and (2) a tone synthesized based on the spectral-temporal structure of a concert triangle. We conducted a detection experiment where participants indicated if the auditory stimulus is heard when presented a range of signal-to-noise (SNR) ratios and a two-alternative force choice task to measure annoyance ratings. Although reductions in SNRs reduced detectability for the standard tone, similar deductions had no meaningful effect on detectability of tones modeled off the musical triangle. Crucially, we identified a number of triangle inspired tones which are both less annoying and more detectable than standard tones. This suggests that these more complex sounds can reduce annoyance without harming detection, offering useful insight to medical device sound design.

Evaluation of a headphones-fitted EEG system for the recording of auditory evoked potentials and mental workload assessment

Advancements in portable neuroimaging technologies open up new opportunities to gain insight into the neural dynamics and cognitive processes underlying day-to-day behaviors. In this study, we evaluated the relevance of a headphone- mounted electroencephalogram (EEG) system for monitoring mental workload. The participants (N = 12) were instructed to pay attention to auditory alarms presented sporadically while performing the Multi-Attribute Task Battery (MATB) whose difficulty was staged across three conditions to manipulate mental workload. The P300 Event-Related Potentials (ERP) elicited by the presentation of auditory alarms were used as probes of attentional resources available. The amplitude and latency of P300 ERPs were compared across experimental conditions. Our findings indicate that the P300 ERP component can be captured using a headphone-mounted EEG system. Moreover, neural responses to alarm could be used to classify mental workload with high accuracy (over 80%) at a single-trial level. Our analyses indicated that the signal-to-noise ratio acquired by the sponge-based sensors remained stable throughout the recordings. These results highlight the potential of portable neuroimaging technology for the development of neuroassistive applications while underscoring the current limitations and challenges associated with the integration of EEG sensors in everyday-life wearable technologies. Overall, our study contributes to the growing body of research exploring the feasibility and validity of wearable neuroimaging technologies for the study of human cognition and behavior in real-world settings.

Correction: Capturing the attentional response to clinical auditory alarms: An ERP study on priority pulses

Correction: Capturing the attentional response to clinical auditory alarms: An ERP study on priority pulses

A Spatiotemporal and Multisensory Approach to Designing Wearable Clinical ICU Alarms.

In health care, auditory alarms are an important aspect of an informatics system that monitors patients and alerts clinicians attending to multiple concurrent tasks. However, the volume, design, and pervasiveness of existing Intensive Care Unit (ICU) alarms can make it difficult to quickly distinguish their meaning and importance. In this study, we evaluated the effectiveness of two design approaches not yet explored in a smartwatch-based alarm system designed for ICU use: (1) using audiovisual spatial colocalization and (2) adding haptic (i.e., touch) information. We compared the performance of 30 study participants using ICU smartwatch alarms containing auditory icons in two implementations of the audio modality: colocalized with the visual cue on the smartwatch's low-quality speaker versus delivered from a higher quality speaker located two feet away from participants (like a stationary alarm bay situated near patients in the ICU). Additionally, we compared participant performance using alarms with two sensory modalities (visual and audio) against alarms with three sensory modalities (adding haptic cues). Participants were 10.1% (0.24s) faster at responding to alarms when auditory information was delivered from the smartwatch instead of the higher quality external speaker. Meanwhile, adding haptic information to alarms improved response times to alarms by 12.2% (0.23s) and response times on their primary task by 10.3% (0.08s). Participants rated learnability and ease of use higher for alarms with haptic information. These small but statistically significant improvements demonstrate that audiovisual colocalization and multisensory alarm design can improve user response times.

Designing, evaluating, and benchmarking auditory alarms for the chemical and oil processing industry

The auditory alarms used in oil and chemical processing control rooms are often based on practices and knowledge which is twenty to thirty years out of date, and therefore do not embody the significant progress that has been more recently made in this area. Best practice available from other areas (aviation, transport, and healthcare) can be brought to bear in improving and updating control room alarms as they share similar problems with alarms in those domains. This paper describes the processes of designing, benchmarking, and testing a series of sets of auditory alarms intended for use in control rooms by the oil and chemical processing industry. In particular, the work shows how important the localizability of alarms can be in practice, and how improved localizability can be designed into auditory alarms.

The effect of working memory load on inattentional deafness during aeronautical decision-making

Operating an aircraft requires pilots to handle a significant amount of multi-modal information, which creates a high working memory load. Detecting auditory alarms in this high-load scenario is crucial for aviation safety. According to cognitive control load theory, an increase in working memory load may enhance distractor interference, resulting in improved detection sensitivity for task-irrelevant stimuli. Therefore, understanding the effect of working memory load on auditory alarm detection is of particular interest in aviation safety research. The studies were designed to investigate the effect of storage load and executive function load of working memory on auditory alarm detection during aeronautical decision-making through three experiments. In Experiment 1 and 2, participants performed an aeronautical decision-making task while also detecting an auditory alarm during the retention interval of a working memory task (visual-spatial, visual-verbal and auditory-verbal). In Experiment 3, participants were required to detect an auditory alarm while performing the 2-back and 3-back aeronautical decision-making tasks. Experiment 1 found that the auditory alarm sensitivity was higher in conditions of low visual-spatial working memory storage load compare to high load conditions. Experiment 2 found that a high storage load of visual-verbal working memory reduced auditory alarm sensitivity but auditory-verbal working memory load did not. Experiment 3 found that, unlike storage load, auditory alarm sensitivity was stronger under high executive function load relative to low executive function load. These findings show that working memory storage load and executive function load have different effects on auditory alarm sensitivity. The relationship between executive function and auditory alarm sensitivity supports cognitive control load theory, while the impact of the storage function on auditory alarm sensitivity does not adhere to this theory.

Improving auditory alarms: Reducing perceived annoyance with musical timbre (a randomized trial)

BackgroundAuditory alarms in medical environments are widely criticized due to problematic design issues affecting learnability, recognition, and annoyance. To overcome these issues, new alarm sets vary properties like pitch, timing, and timbre—the “quality” of a sound. Past work identifies timbre as a promising candidate for improving alarm recognition, however most studies manipulate multiple acoustic parameters, obfuscating the independent effect of timbre on melodic perception. MethodsTo better understand timbre's potential for improving alarm recognizability and reducing annoyance, we recruited forty-four participants for a melody recognition experiment. In a learning phase, participants learned short alarm melodies performed with either a complex musical timbre based on a xylophone or one following the specifications of a universal alarm standard. During a recall phase, participants heard the melodies again presented in either the xylophone or standard timbre and attempted to identify the corresponding label for each alarm. Afterward, participants heard alarm pairs presented in both timbres and chose which one they perceived to be more annoying. ResultsParticipants recalled xylophone alarm melodies with comparable accuracy to the standard timbre, however they found the musical timbre substantially less annoying. Regardless of the timbre at exposure, recognition of familiar melodies decreased if the timbre changed between learning and recall. ConclusionsWe compared the recognizability and annoyance of alarm melodies presented in either a standard alarm timbre or a synthesized xylophone timbre. Our findings reveal musical sounding alarms are comparably recognizable, yet significantly less annoying than alarm signals common in medical environments. These outcomes provide a promising first step to improving patient care through musically informed alarm design.

Effects of multitasking on interpreting a spearcon sequence display for monitoring multiple patients

Spearcons are time-compressed speech phrases. When arranged in a sequence representing vital signs of multiple patients, spearcons may be more informative than conventional auditory alarms. However, multiple resource theory suggests that certain timeshared tasks might interfere with listeners’ ability to understand spearcons. We tested the relative interference with spearcon identification from the following ongoing tasks: (1) manual tracking, (2) linguistic detection of spoken target words, (3) arithmetic true-false judgments, or (4) an ignored background speech control. Participants were 80 non-clinicians. The linguistic task worsened spearcon identification more than the tracking task, p < .001, and more than ignored background speech, p = .012. The arithmetic task worsened spearcon identification more than the tracking task, p < .001. The linguistic task and arithmetic task both worsened performance, p = .674. However, no ongoing task affected participants’ ability to detect which patient(s) in a sequence had abnormal vital signs. Future research could investigate whether timeshared tasks affect non-speech auditory alerts.

Repeatable effects of synchronizing perceptual tasks with heartbeat on perception-driven situation awareness

The paper presents repeatable effects of synchronizing visual and auditory alarms with heartbeats on the availability of cognitive resources. A perception-driven situation awareness model is proposed and studied by implementing two distinct experimental protocols with different groups of participants. Results of a first study with a single-screen configuration are repeated by those of a second one on a multiple-screen context. Both experimental protocols rely on manipulating a between-subjects factor to compare two conditions - one with alarms activated synchronously with heart rate and one with alarms non-synchronized with heart rate - and a within-subjects factor to compare the impact of workload by increasing the level of task difficulty. Results about mono-screen and multi-screen configurations are homogenous. The synchronous condition makes people produce significantly more errors and fewer visual scans of the alarm display area. This degradation of perceptual abilities is non-conscious and is correlated with workload. Main people are not aware about their actual performance and this is confirmed by the evolution of subjective performance and frustration regarding task difficulty, display configuration and alarm activation condition. Such discrepancies between what it is looked at with what it is actually perceived and between actual and perceived indicators like performance are perceptual dissonances that are relevant for perception-driven situation awareness. The application of synchronizing dynamic events with heartbeats will be studied for different individual and collective work contexts in order to extend the proposed perception-driven situation awareness model based on perceptual dissonance management and on human capability parameters.

Creating safe environments: optimal acoustic alarming of laypeople in fire prevention

Hazards like fires occur regularly and can cost people’s lives. Optimal auditory alarm signals enable laypeople to recognise dangers and to protect themselves. Existing fire alarm sound research focuses on alarm sounds and voice alerts presented singularly. We explored a combination of both and aimed to identify alarm signals that work optimally in everyday life. Thus, we conducted two online experiments: In Study 1 (N = 379), we tested eight alarm sounds regarding their typicality, their familiarity, their arousal, their valence, and their dominance. Siren-like alarm sounds were the most effective. In Study 2 (N = 206), we combined the four most effective alarm sounds with a voice alert. The voice alert reinforced ambiguity reduction, action motivation, and action intention. Hence, we suggest using alarm sounds with siren-like patterns. They should be combined with a voice alert to foster a quick and specific (target task-oriented) reaction. Practitioner summary: Warning laypeople is of great importance in time-critical hazards. In two remote testing studies (N Total = 585), auditory alarm sounds with siren-like patterns resulted in the most distinct and emotional perception. Combining the alarm sound with a voice alert adds meaning to the alarm and fosters action intention. Abbreviations: DIN: Deutsches Institut für Normung [German Institute for Standardization]; ISO: International Organization for Standardization; Mixed MANOVA: mixed measures multivariate analysis of variance; rmMANOVA: repeated measures multivariate analysis of variance.

Capturing the attentional response to clinical auditory alarms: An ERP study on priority pulses.

Clinical auditory alarms are often found in hospital wards and operating rooms. In these environments, regular daily tasks can result in having a multitude of concurrent sounds (from staff and patients, building systems, carts, cleaning devices, and importantly, patient monitoring devices) which easily amount to a prevalent cacophony. The negative impact of this soundscape on staff and patients' health and well-being, as well as in their performance, demand for accordingly designed sound alarms. The recently updated IEC60601-1-8 standard, in guidance for medical equipment auditory alarms, proposed a set of pointers to distinctly convey medium or high levels of priority (urgency). However, conveying priority without compromising other features, such as ease of learnability and detectability, is an ongoing challenge. Electroencephalography, a non-invasive technique for measuring the brain response to a given stimulus, suggests that certain Event-Related Potentials (ERPs) components such as the Mismatch Negativity (MMN) and P3a may be the key to uncovering how sounds are processed at the pre-attentional level and how they may capture our attention. In this study, the brain dynamics in response to the priority pulses of the updated IEC60601-1-8 standard was studied via ERPs (MMN and P3a), for a soundscape characterised by the repetition of a sound (generic SpO2 "beep"), usually present in operating and recovery rooms. Additional behavioural experiments assessed the behavioural response to these priority pulses. Results showed that the Medium Priority pulse elicits a larger MMN and P3a peak amplitude when compared to the High Priority pulse. This suggests that, at least for the applied soundscape, the Medium Priority pulse is more easily detected and attended at the neural level. Behavioural data supports this indication, showing significantly shorter reaction times for the Medium Priority pulse. The results pose the possibility that priority pointers of the updated IEC60601-1-8 standard may not be successfully conveying their intended priority levels, which may not only be due to design properties but also to the soundscape in which these clinical alarms are deployed. This study highlights the need for intervention in both hospital soundscapes and auditory alarm design settings.

Auditory Sequences Presented With Spearcons Support Better Multiple Patient Monitoring Than Single-Patient Alarms: A Preclinical Simulation.

A study of auditory displays for simulated patient monitoring compared the effectiveness of two sound categories (alarm sounds indicating general risk categories from international alarm standard IEC 60601-1-8 versus event-specific sounds according to the type of nursing unit) and two configurations (single-patient alarms versus multi-patient sequences). Fieldwork in speciality-focused high dependency units (HDU) indicated that auditory alarms are ambiguous and do not identify which patient has a problem. We tested whether participants perform better using auditory displays that identify the relevant patient and problem. During simulated patient monitoring of four patients in a respiratory HDU, 60 non-clinicians heard either (a) IEC risk categories as single-patient alarm sounds, (b) event-specific categories as single-patient alarm sounds, (c) IEC risk categories in multi-patient sequences or (d) event-specific categories in multi-patient sequences. Participants performed a perceptual-motor task while monitoring patients; after detecting abnormal events, they identified the patient and the event. Participants hearing multi-patient sequences made fewer wrong patient identifications than participants hearing single-patient alarms. Advantages of event-specific categories emerged when IEC risk category sounds indicated more than one potential event. Even when IEC and event-specific sounds indicated the same unique event, spearcons supported better event identification than did auditory icon sounds. Auditory displays that unambiguously convey which patient is having what problem dramatically improve monitoring performance in a preclinical HDU simulation. Time-compressed speech assists development of detailed risk categories needed in specific HDU contexts, and multi-patient sound sequences allow multiple patient wellbeing to be monitored.

More detectable, less annoying: Temporal variation in amplitude envelope and spectral content improves auditory interface efficacy

Auditory interfaces, such as auditory alarms, are useful tools for human computer interaction. Unfortunately, poor detectability and annoyance inhibit the efficacy of many interface sounds. Here, it is shown in two ways how moving beyond the traditional simplistic temporal structures of normative interface sounds can significantly improve auditory interface efficacy. First, participants rated tones with percussive amplitude envelopes as significantly less annoying than tones with flat amplitude envelopes. Crucially, this annoyance reduction did not come with a detection cost as percussive tones were detected more often than flat tones-particularly, at relatively low listening levels. Second, it was found that reductions in the duration of a tone's harmonics significantly lowered its annoyance without a commensurate reduction in detection. Together, these findings help inform our theoretical understanding of detection and annoyance of sound. In addition, they offer promising original design considerations for auditory interfaces.

The Duration of an Auditory Icon Can Affect How the Listener Interprets Its Meaning

Initially introduced in the field of informatics, an auditory icon consists of a short sound that is present in everyday life, used to represent a specific event, object, function, or action. Auditory icons have been studied in various fields, and overall, compared to other types of auditory alarms, they can be very efficient in informing the listener about a situation or event. So far, auditory icons have been used with a wide range of durations, ranging from a few hundreds of milliseconds up to several seconds. Still little is known, however, about whether and how icon duration influences its interpretation. In the present study, we therefore asked listeners to rate 12 auditory icons, divided into four different sound categories (nonverbal human sounds, machine sounds, human activities, and animal vocalizations), in five different durations (200, 400, 800, 1,600, and 3,200 ms). They rated (1) how appropriately the icon sound itself represented the icon's referent and (2) how appropriately each duration of the icon sound represented the icon's referent. Overall, results demonstrate that the duration of the auditory icons in this stimulus set can directly affect how the icon represents the referent. Auditory icons in the test set characterized by human activities represented their referent most appropriately in a relatively shorter duration (400 or 800 ms). The majority of the auditory icons in the set consisting of machine sounds, nonverbal human sounds , and animal vocalizations , however, were considered as more appropriately representing their referent in longer durations (800 ms and 1,600 ms). Further systematic research is necessary to determine whether the duration effects shown here may generalize to other stimulus sets.

Signaling Patient Oxygen Desaturation with Enhanced Pulse Oximetry Tones

Manufacturers could improve the pulse tones emitted by pulse oximeters to support more accurate identification of a patient's peripheral oxygen saturation (SpO2) range. In this article, we outline the strengths and limitations of the variable-pitch tone that represents SpO2 of each detected pulse, and we argue that enhancements to the tone to demarcate clinically relevant ranges are feasible and desirable. The variable-pitch tone is an appreciated and trusted feature of the pulse oximeter's user interface. However, studies show that it supports relative judgments of SpO2 trends over time and is less effective at supporting absolute judgments about the SpO2 number or conveying when SpO2 moves into clinically important ranges. We outline recent studies that tested whether acoustic enhancements to the current tone could convey clinically important ranges more directly, without necessarily using auditory alarms. The studies cover the use of enhanced variable-pitch pulse oximeter tones for neonatal and adult use. Compared with current tones, the characteristics of the enhanced tones represent improvements that are both clinically relevant and statistically significant. We outline the benefits of enhanced tones, as well as discuss constraints of which developers of enhanced tones should be aware if enhancements are to be successful.

Attention Limitations in the Detection and Identification of Alarms in Close Temporal Proximity.

The aim of this study was to establish the effects of simultaneous and asynchronous masking on the detection and identification of visual and auditory alarms in close temporal proximity. In complex and highly coupled systems, malfunctions can trigger numerous alarms within a short period of time. During such alarm floods, operators may fail to detect and identify alarms due to asynchronous and simultaneous masking. To date, the effects of masking on detection and identification have been studied almost exclusively for two alarms during single-task performance. This research examines 1) how masking affects alarm detection and identification in multitask environments and 2) whether those effects increase as a function of the number of alarms. Two experiments were conducted using a simulation of a drone-based package delivery service. Participants were required to ensure package delivery and respond to visual and auditory alarms associated with eight drones. The alarms were presented at various stimulus onset asynchronies (SOAs). The dependent measures included alarm detection rate, identification accuracy, and response time. Masking was observed intramodally and cross-modally for visual and auditory alarms. The SOAs at which asynchronous masking occurred were longer than reported in basic research on masking. The effects of asynchronous and, even more so, simultaneous masking became stronger as the number of alarms increased. Masking can lead to breakdowns in the detection and identification of alarms in close temporal proximity in complex data-rich domains. The findings from this research provide guidance for the design of alarm systems.

Benchmarking cEEGrid and Solid Gel-Based Electrodes to Classify Inattentional Deafness in a Flight Simulator.

Transfer from experiments in the laboratory to real-life tasks is challenging due notably to the inability to reproduce the complexity of multitasking dynamic everyday life situations in a standardized lab condition and to the bulkiness and invasiveness of recording systems preventing participants from moving freely and disturbing the environment. In this study, we used a motion flight simulator to induce inattentional deafness to auditory alarms, a cognitive difficulty arising in complex environments. In addition, we assessed the possibility of two low-density EEG systems a solid gel-based electrode Enobio (Neuroelectrics, Barcelona, Spain) and a gel-based cEEGrid (TMSi, Oldenzaal, Netherlands) to record and classify brain activity associated with inattentional deafness (misses vs. hits to odd sounds) with a small pool of expert participants. In addition to inducing inattentional deafness (missing auditory alarms) at much higher rates than with usual lab tasks (34.7% compared to the usual 5%), we observed typical inattentional deafness-related activity in the time domain but also in the frequency and time-frequency domains with both systems. Finally, a classifier based on Riemannian Geometry principles allowed us to obtain more than 70% of single-trial classification accuracy for both mobile EEG, and up to 71.5% for the cEEGrid (TMSi, Oldenzaal, Netherlands). These results open promising avenues toward detecting cognitive failures in real-life situations, such as real flight.

Signaling Patient Oxygen Desaturation with Enhanced Pulse Oximetry Tones.

Manufacturers could improve the pulse tones emitted by pulse oximeters to support more accurate identification of a patient's peripheral oxygen saturation (SpO2) range. In this article, we outline the strengths and limitations of the variable-pitch tone that represents SpO2 of each detected pulse, and we argue that enhancements to the tone to demarcate clinically relevant ranges are feasible and desirable. The variable-pitch tone is an appreciated and trusted feature of the pulse oximeter's user interface. However, studies show that it supports relative judgments of SpO2 trends over time and is less effective at supporting absolute judgments about the SpO2 number or conveying when SpO2 moves into clinically important ranges. We outline recent studies that tested whether acoustic enhancements to the current tone could convey clinically important ranges more directly, without necessarily using auditory alarms. The studies cover the use of enhanced variable-pitch pulse oximeter tones for neonatal and adult use. Compared with current tones, the characteristics of the enhanced tones represent improvements that are both clinically relevant and statistically significant. We outline the benefits of enhanced tones, as well as discuss constraints of which developers of enhanced tones should be aware if enhancements are to be successful.

The Influence of Audible Alarm Loudness and Type on Clinical Multitasking.

In high-consequence industries such as health care, auditory alarms are an important aspect of an informatics system that monitors patients and alerts providers attending to multiple concurrent tasks. Alarms levels are unnecessarily high and alarm signals are uninformative. In a laboratory-based task setting, we studied 25 anesthesiology residents' responses to auditory alarms in a multitasking paradigm comprised of three tasks: patient monitoring, speech perception/intelligibility, and visual vigilance. These tasks were in the presence of background noise plus/minus music, which served as an attention-diverting stimulus. Alarms signified clinical decompensation and were either conventional alarms or a novel informative auditory icon alarm. Both alarms were presented at four different levels. Task performance (accuracy and response times) were analyzed using logistic and linear mixed-effects regression. Salient findings were 1), the icon alarm had similar performance to the conventional alarm at a +2dB signal-to-noise-ratio (SNR) (accuracy: OR 1.21 (95% CI 0.88, 1.67), response time: 0.04s at 2dB (95% CI: -0.16, 0.24), which is a much lower level than current clinical environments; 2) the icon alarm was associated with 27% greater odds (95% CI: 18%, 37%) of correctly addressing the vigilance task, regardless of alarm SNR, suggesting crossmodal/multisensory multitasking benefits; and 3) compared to the conventional alarm, the icon alarm was associated with an absolute improvement in speech perception of 4% in the presence of an attention-diverting auditory stimulus (p = 0.031). These findings suggest that auditory icons can provide multitasking benefits in cognitively demanding clinical environments.

Advanced Alarm Method Based on Driver’s State in Autonomous Vehicles

In autonomous driving vehicles, the driver can engage in non-driving-related tasks and does not have to pay attention to the driving conditions or engage in manual driving. If an unexpected situation arises that the autonomous vehicle cannot manage, then the vehicle should notify and help the driver to prepare themselves for retaking manual control of the vehicle. Several effective notification methods based on multimodal warning systems have been reported. In this paper, we propose an advanced method that employs alarms for specific conditions by analyzing the differences in the driver’s responses, based on their specific situation, to trigger visual and auditory alarms in autonomous vehicles. Using a driving simulation, we carried out human-in-the-loop experiments that included a total of 38 drivers and 2 scenarios (namely drowsiness and distraction scenarios), each of which included a control-switching stage for implementing an alarm during autonomous driving. Reaction time, gaze indicator, and questionnaire data were collected, and electroencephalography measurements were performed to verify the drowsiness. Based on the experimental results, the drivers exhibited a high alertness to the auditory alarms in both the drowsy and distracted conditions, and the change in the gaze indicator was higher in the distraction condition. The results of this study show that there was a distinct difference between the driver’s response to the alarms signaled in the drowsy and distracted conditions. Accordingly, we propose an advanced notification method and future goals for further investigation on vehicle alarms.