“Beep Beep”- Can someone turn that off?

Image of alarm silence and pause buttons on an ICU monitor Philips Healthcare

Working as a Patient Care Technician in the Intensive Care Unit of a hospital, I hear medical alarms and monitoring systems making a variety of different beeping sounds all day. Sometimes I come home from a shift and still hear the noises when I’m trying to sleep. This experience is felt by many healthcare workers. Medical alarms are vital to healthcare by alerting providers to critical information while maintaining privacy for patients. However, often the sounds can become very piercing over time and can lead to providers experiencing alarm annoyance where they turn off or silence alarms. This can cause them to miss important information and lead to adverse outcomes for patients. Some alarms are redundant, such as beeping every single time a patient takes a breath, or not context dependent, such as alerting that a patient isn’t breathing when a provider is placing a breathing tube for that very reason. These alarms can also lead to alarm fatigue for healthcare workers, which is a sensory overload due to all of the noise.

If the current state of medical alarms can be so dangerous to both healthcare workers and patients, is anyone working to create change? Dr. Michael Schutz and colleagues at McMaster University are studying the amplitude envelope, a lesser known property of sound, that could potentially help improve the acoustics of medical alarms.

The amplitude envelope is defined as the changes in a sound’s energy over time. Schutz’s team talks about two different kinds of tones: percussive and flat. Percussive tones start abruptly and then begin to exponentially decrease. They occur in everyday life when two objects bang into each other. Flat tones, like alarms, start and stop abruptly and can only be created by synthesis. Their abrupt stop makes it harder for our perceptual systems to gather information about their offset and in turn makes it harder for us to make judgements based on the sound and learn sound-object associations. Humans and animals make percussive tones and they are also used in many different musical instruments. In contrast, flat tones do not occur naturally, which contributes to their negative effects in medical alarms. Schutz believes that incorporating percussive tones in medical alarms could be a potential improvement.

In their 2021 article, “Decaying amplitude envelopes reduce alarm annoyance: Exploring new approaches to improving auditory interfaces,” Sreetharan et al. performed three experiments to look at the effect of these percussive tones on alarms. In their first experiment, they created both percussive and flat alarms for oxygenation, ventilation, cardiovascular functioning, temperature, perfusion, infusion, and general equipment problems. 40 participants were randomly assigned to one of the groups and the researchers measured their memory for associations of the alarm and annoyance ratings. In experiment two, they repeated the experiment with more complex tones. In the last experiment, they looked more at alarm annoyance. This time they recruited 72 participants who were split up into the percussive or flat alarm groups. They used the same complex tones from experiment two and had participants rate their annoyance before and after hearing the tone, instead of just after the tone. All participants also had equal exposure to the tone instead of based on how quickly they learned which medical issue it was associated with.

The researchers found no significant difference between the percussive and flat alarm groups in how long it took them to identify and associate the alarm correctly for experiments one and two. This gives evidence that percussive alarms could be just as, if not more, effective than flat alarms in a real life medical setting. They also found that in both experiments one and two, participants rated percussive alarms as less annoying than flat alarms. In experiment three, they again found that there was no difference in participants’ abilities to learn and identify the alarms. They also found that for annoyance ratings measured before and after hearing the tone, participants again found percussive alarms less annoying than flat alarms.

Overall, the researchers found that percussive alarms had significantly lower annoyance ratings than flat alarms while taking the same time to learn or identify. These results show that implementing percussive alarms in healthcare settings could be a helpful alternative in combating issues healthcare workers face and improving patient outcomes. More research is required to figure out exactly why percussive tones are perceived as less annoying, but the researchers hypothesized that a large reason is due to their presence in the natural environment, which has allowed humans to become comfortable with them. Even though sometimes an annoying alarm can be useful to alert in a critical situation, alarms that are just there to monitor nonemergent vitals or communicate information could benefit from percussive sounds. Percussive alarms and focusing on the amplitude envelope are a great start to creating safer healthcare environments.

Reference: Sreetharan, S., Schlesinger, J. J., & Schutz, M. (2021). Decaying amplitude envelopes reduce alarm annoyance: Exploring new approaches to improving auditory interfaces. Applied Ergonomics, 96, 103432. https://doi.org/10.1016/j.apergo.2021.103432