Searching for Meaning in Sound: Learning and Interpreting Alarm Signals in Visual Environments

Given the ease with which the diverse array of environmental sounds can be understood, the difficulties encountered in using auditory alarm signals on medical devices are surprising. In two experiments, with nonclinical participants, alarm sets which relied on similarities to environmental sounds (concrete alarms, such as a heartbeat sound to indicate "check cardiovascular function") were compared to alarms using abstract tones to represent functions on medical devices. The extent to which alarms were acoustically diverse was also examined: alarm sets were either acoustically different or acoustically similar within each set. In Experiment 1, concrete alarm sets, which were also acoustically different, were learned more quickly than abstract alarms which were acoustically similar. Importantly, the abstract similar alarms were devised using guidelines from the current global medical device standard (International Electrotechnical Commission 60601-1-8, 2012). Experiment 2 replicated these findings. In addition, eye tracking data showed that participants were most likely to fixate first on the correct medical devices in an operating theater scene when presented with concrete acoustically different alarms using real world sounds. A new set of alarms which are related to environmental sounds and differ acoustically have therefore been proposed as a replacement for the current medical device standard. Public Significance Statement Current guidance given in international standards suggests using "families" of related tones to represent functions on medical devices. However, the tones are hard to distinguish from one another and their meanings are unclear. This research showed that alarm signals which were related to the real world (e.g., a heartbeat sound to indicate "check cardiovascular function") rather than tones were much more easily learned especially when they could be easily discriminated from one another acoustically. Alarm signals like these direct attention more effectively to appropriate medical equipment and are set to replace the current international standard alarms in late 2019 or early 2020.