Noise quantification in the intensive care unit of a tertiary care hospital

Figure 1 Maximum sound level scatter plot over 4 months (5443 time windows). WHO: World Health Organization; Lmax: The highest sound level recorded during the measurement period (30 minutes); Dec: December; Jan: January; Feb: February; Mar: March.

Figure 2 Diurnal variation in L10, L50, L90 (representing sound levels exceeding 10%, 50%, and 90% of the time, respectively), equivalent continuous noise level, maximum sound level and sound exposure level (Baseline values were defined as the overall mean during stable periods; percentage change reflects deviation relative to baseline). A: L10 - noise levels exceeded for 10% of the time; B: L50 - noise levels exceeded for 50% of the time; C: L90 - noise levels exceeded for 90% of the time; D: Equivalent continuous noise level. The average sound energy over a given time period; E: The highest sound level recorded during the measurement period; F: Sound exposure level is the total energy of a sound event, normalized to 1 second. L10, L50, L90: Representing sound levels exceeding 10%, 50%, and 90% of the time, respectively; LEQ: Equivalent continuous noise level; Lmax: Maximum sound level; SEL: Sound exposure level.

Figure 3 Heat maps illustrating the 24-hour acoustic cycle of different noise parameters measured in half-hour intervals over the study period. The color intensity indicates the relative magnitude of the acoustic parameter during the respective time intervals. Scale bar: 30 minutes. A: L10 - noise levels exceeded for 10% of the time; B: L50 - noise levels exceeded for 50% of the time; C: L90 - noise levels exceeded for 90% of the time; D: Equivalent continuous sound level. The average sound energy over a given time period; E: The highest sound level recorded during the measurement period; F: Sound exposure level is the total energy of a sound event, normalized to 1 second. L10, L50, L90: Representing sound levels exceeding 10%, 50%, and 90% of the time, respectively; LEQ: Equivalent continuous noise level; Lmax: Maximum sound level; SEL: Sound exposure level.

Figure 4 The 24-hour average of equivalent continuous noise level, L90, L10 and maximum sound level. L10 - noise levels exceeded for 10% of the time; L90 - noise levels exceeded for 90% of the time. L90 is often considered background noise. L10, L90: Representing sound levels exceeding 10% and 90% of the time, respectively; LEQ: Equivalent continuous noise level; Lmax: Maximum sound level; WHO: World Health Organization; ICU: Intensive care unit.