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

Abstract

Background: Noise in intensive care units (ICUs) frequently exceeds recommended levels [the World Health Organization (WHO) recommends equivalent continuous noise level (Leq) < 35 dB], arising from alarms, equipment, and staff activity. Elevated sound can disrupt patients' sleep, increase stress, and impair recovery.

Aim: To identify the extent of noise exposure in the ICU.

Methods: This observational study was conducted in the adult ICU of a tertiary care hospital. Noise was measured using the SERRAX SLM1090 sound level meter, which was placed in the center of the 10-bed ICU at a height of 6 feet above ground level. A 30-minute time window was set to obtain half-hourly Leq, L10, L50, L90 (representing sound levels exceeding 10%, 50%, and 90% of the time, respectively), and maximum sound level (Lmax).

Results: Data were collected over 4 months (December 2024 to March 2025), yielding 5443 half-hourly recordings. The average Leq, Lmax, L10, L50, L90 and sound exposure level were 64.8 ± 2.8 dB, 82.5 ± 4.4 dB, 67.5 ± 2.9 dB, 61.4 ± 3.2 dB, 56.4 ± 2.8 dB and 97.7 ± 2.8 dB, respectively. Nurses' handover, visitation and twilight hours were the noisiest. Nighttime (1:00 hours to 3:00 hours) was the quietest in the ICU. Lmax in the ICU exceeded the WHO cut-offs for industrial sounds and public addresses of 75 dB and 85 dB in 96.7% and 25.5% of readings, respectively. Twenty-four-hour cumulative sound exposure to the patient for night and evening-night penalties were 68 dB and 70 dB, respectively.

Conclusion: The noise exposure in the ICU persistently exceeded WHO-recommended thresholds. Maximum noise occurred during handovers, visitation and twilight activities, indicating that these times would be the most effective for intervention.