Characterizing impulsiveness of hospital sound environments

Hospitals have highly impulsive sound environments and alarms are one of the dominant transient sound sources in Intensive Care Units (ICUs). The maximum (Lmax) and peak (Lpeak) sound pressure levels are two noise indices that have been commonly used to document the impulsiveness of hospital sound environments. Even though these traditional noise indices provide a good general overview of the hospital sound environments, they are limited in their usefulness. A recent study used a newer noise index called "occurrence rate" to further document the impulsiveness of critical care settings and suggested its effectiveness in capturing nurse perceptions. This paper further evaluates the effectiveness of this newer noise index by statistically relating occurrence rate to nurse perceptions in two ICUs at different times of the day and days of the week. Interestingly, differences between nurse annoyance and loudness perceptions in the two ICUs were statistically related with the differences between impulsive characteristics of two ICU sound environments captured by the occurrence rate index. Since alarms are one of the dominant impulsive ICU sounds, this study also assesses the impact of alarms by analyzing the differences between nurse perception of alarms versus overall noise levels caused by various non-alarm sources in the workplace. Surprisingly, nurses in both ICUs perceived alarms as nearly as disruptive as overall noise with regards to effects on work performance, health, anxiety, loudness and annoyance. In both units many of the nurses (56% total) indicated that they sometimes tune out alarms.