Objective: In this work, we systematically evaluated the reserved alarm sounds of the IEC 60601-1-8 international medical alarm standard to determine when and how they can be totally and partially masked.
Background: IEC 60601-1-8 gives engineers instruction for creating human-perceivable auditory medical alarms. This includes reserved alarm sounds: common types of alarms where each is a tonal melody. Even when this standard is honored, practitioners still fail to hear alarms, causing practitioner nonresponse and, thus, potential patient harm. Simultaneous masking, a condition where one or more alarms is imperceptible in the presence of other concurrently sounding alarms due to limitations of the human sensory system, is partially responsible for this.
Methods: In this research, we use automated proof techniques to determine if masking can occur in a modeled configuration of medical alarms. This allows us to determine when and how reserved alarm sound can mask other reserved alarms and to explore parameters to address discovered problems.
Results: We report the minimum number of other alarm sounds it takes to both totally and partially mask each of the high-, medium-, and low-priority alarm sounds from the standard.
Conclusions: Significant masking problems were found for both the total and partial masking of high-, medium-, and low-priority reserved alarm sounds.
Application: We show that discovered problems can be mitigated by setting alarm volumes to standard values based on priority level and by randomizing the timing of alarm tones.
Keywords: audition; computational modeling; medical devices and technologies; patient safety; psychophysical methods.