Improving auditory alarms: Reducing perceived annoyance with musical timbre (a randomized trial)

Background Auditory alarms in medical environments are widely criticized due to problematic design issues affecting learnability, recognition, and annoyance. To overcome these issues, new alarm sets vary properties like pitch, timing, and timbre—the “quality” of a sound. Past work identifies timbre as a promising candidate for improving alarm recognition, however most studies manipulate multiple acoustic parameters, obfuscating the independent effect of timbre on melodic perception. Methods To better understand timbre's potential for improving alarm recognizability and reducing annoyance, we recruited forty-four participants for a melody recognition experiment. In a learning phase, participants learned short alarm melodies performed with either a complex musical timbre based on a xylophone or one following the specifications of a universal alarm standard. During a recall phase, participants heard the melodies again presented in either the xylophone or standard timbre and attempted to identify the corresponding label for each alarm. Afterward, participants heard alarm pairs presented in both timbres and chose which one they perceived to be more annoying. Results Participants recalled xylophone alarm melodies with comparable accuracy to the standard timbre, however they found the musical timbre substantially less annoying. Regardless of the timbre at exposure, recognition of familiar melodies decreased if the timbre changed between learning and recall. Conclusions We compared the recognizability and annoyance of alarm melodies presented in either a standard alarm timbre or a synthesized xylophone timbre. Our findings reveal musical sounding alarms are comparably recognizable, yet significantly less annoying than alarm signals common in medical environments. These outcomes provide a promising first step to improving patient care through musically informed alarm design.