Abstract
BACKGROUND: Noise adversely affects preterm infants in the neonatal intensive care unit (NICU), but past studies focused exclusively on quantifying its acoustic characteristics. PURPOSE: This study aims to examine the relationships between objective noise measurements and nurses' subjective perceptions in the NICU and analyze how these measurements vary by location and time of day during quiet hours. METHODS: In this observational study, noise was measured in 12 bays of an open-bay NICU during set times in the morning, afternoon, and evening. Subjective ratings of perceived noise were solicited from 25 nurses during these periods, converted to numerical scores, and ranked to categorize the bays into 3 measurement areas: loud, intermediate, and quiet. Noise indices were tested for associations with noise score, measurement area, and time by correlation and variance analyses. RESULTS: The equivalent continuous sound level ( Leq ) ranged from 55 to 63 dB over 60-minute measurement periods. The L5 (level exceeded 5% of the 60-minute period) and the L50 (level exceeded 50% of the 60-minute period) were analyzed to capture short-duration high noise levels and typical ambient noise, respectively. Noise ratings showed weak correlations with Leq , L5 , L50 , and minimum sound levels (L min ). IMPLICATIONS FOR PRACTICE AND RESEARCH: Strategies that consider location and time of day, with measures against sudden noise, are needed for NICU care. Future research should address comprehensive assessments of noise sources and their impact evaluation on preterm infants.