Bennett, C., McNeer, R., & Leider, C. (2011). Urgency Analysis of Audible Alarms in The Operating Room. In International Society for Music Information Retrieval Conference (pp. 771-776).

The objective of this study was to observe the acoustic features of audible alarms used in intraoperative environments. IEC-recommended alarms were used. The following table ilustrates these alarms, differentiated by various short melodies.

 

 

The first goal was to observe the primary salient auditory features of the IEC alarm set and to compare it to those of the experimental set. The second goal was to investigate the acoustical correlates of urgency perception.

Besides IEC sounds used as control stimuli, a new experimental set was developed by applying various audio effects to a pure-tone carrier; Since IEC alarms only manipulate melodic and temporal features, the experimental set manipulated: amplitude modulation, waveshaping, frequency modulation, phase randomization, and other basic sound synthesis and processing techniques.

Participants were presented 8 IEC alarms and 7 experimental alarms via two loudspeakers. Their task was to perceptually rate the stimuli on a 9-point Likert scale according to their perceived sense of urgency, anxiety, attention, and severity.

Results

The results showed that urgency was collinear (R2 = 0.95) with all of the other descriptors. As a result, the other descriptions (anxiety, attention, and severity) were removed from further analysis.

IEC alarms exhibited one auditory feature correlated with urgency, and the experimental alarms exhibited five.

Combined analyses of both data sets indicate that changes in an alarm’s spectral features over time are the largest contributor to perceived urgency.