Evaluating the effects of amplitude envelope manipulation on reducing auditory alarm annoyance

Abstract

Auditory alarm annoyance plagues clinicians, which results in alarms desensitization and ultimately affects patient care. Contributing to this problem are the International Electrotechnical Commission (IEC) 60601-1-8 alarms, a standardized set of melodic alarms used to convey information to clinicians in intensive care units. By design, IEC alarms employ flat amplitude (i.e., amplitude invariant) envelopes and are not reflective of naturally occurring sounds with percussive amplitude (i.e., decaying) envelopes. We present a series of three experiments evaluating the effect of amplitude envelope manipulation (i.e., incorporating percussive envelope) on memory and annoyance in IEC alarms synthesized using pure tones (experiment 1), complex tones (experiment 2) and assessing annoyance pre and post memory assessment (experiment 3). For the memory assessment, participants were assigned to learn either the flat alarms or percussive alarms. During the memory assessment, participants were informed of the alarm–referent pairings (study phase), practised identifying alarms (training phase), had a short break, and tested on their ability to identify alarms (evaluation phase). The annoyance assessment was a two alternative forced choice task where participants identified which alarm they perceived to be more annoying from a pair of alarms differing in either envelope-type or alarm-type. Across all experiments there was no difference in alarm learnability between those learning either flat or percussive alarms during the memory assessment. Annoyance assessments revealed that all participants chose the flat alarms to be more annoying than the percussive alarms, independent of the memory assessment condition. These results showcase the potential of using percussive alarms to reduce alarm annoyance without harming learnability, a cost-efficient manipulation.