A Formal Analysis of Masking Between Reserved Alarm Sounds of the IEC 60601-1-8 International Medical Alarm Standard

Abstract

The IEC 60601-1-8 international medical alarm standard was created to give engineers guidance for designing alarms that are easily perceivable by humans. Included within this are a number of reserved alarm sounds that use tonal melodies to represent common types of alarms. Despite the standard, practitioners can still fail to hear and respond to alarms. This can have a profound negative impact on patient life and health. One of the factors that contributes to this problem is simultaneous masking: a condition where one or more alarms can be rendered imperceptible in the presence of other alarms due to limitations of the human perception system. Unfortunately, the tonal nature of the IEC 60601-1-8 reserved sounds makes them particularly susceptible to masking. It can be difficult to determine how masking can manifest in a collection of alarms that can sound concurrently given the inherent complexity of the statespace. In this work, we employ a computational method that employs mathematical proof techniques to determine if masking is possible in a model of a configuration of medical alarms. We use this to analyze the low and medium priority reserved alarm sounds of the IEC 60601-1-8 standard. We describe our method, present the results of our analyses, discuss these results, and explore future research directions.