Scalable Auditory Alarms

Abstract

In information dense, visually complex environments (e.g., automobiles, airplanes, and operating rooms) auditory alarms can direct attention to critical events. Effective alarms are designed to convey a hazard level appropriate for the situation they represent. Acoustic intensity plays an essential role in perceived urgency, with louder sounds generally being perceived as representing something more urgent. However, intensity may be dictated by factors outside the alarm designer’s control (e.g., background noise, manufacturer’s sound system specifications). Therefore it is essential to examine other acoustic parameters that can be used to convey scalable levels of perceived urgency. Previous work suggests that looming sounds, or sounds perceived to be coming towards a listener, may result in faster response times than other types of sounds. Further, people may respond faster to looming sounds if the rate of change (ROC) in the increase in intensity is more rapid, potentially making them a strong candidate for scalability. Sounds increasing in intensity quickly may be perceived as more urgent than other sounds. However, it is critical that ROC is not confounded by overall intensity, since the intensity-urgency relationship is well documented. The present study measured perceived urgency ratings of auditory looming stimuli with different intensity ROCs that were equated for overall intensity. Results revealed no differences in urgency ratings across the three ROCs. Current results indicate that overall intensity is more critical than ROC to achieving scalability in auditory alarms.