What’s that noise—tackling sound pollution in the NICU: a systematic review

Background: Preterm infants are highly susceptible to environmental influences due to the immaturity of their sensory and neurological systems. In neonatal intensive care units (NICUs), ambient noise frequently exceeds recommended thresholds and may interfere with auditory and neurodevelopmental maturation. During a critical period of sensory refinement, infants are exposed to unpredictable, high-intensity soundscapes generated by alarms, respiratory devices, and staff activity, contrasting sharply with the regulated acoustic environment of the womb. Aim: This systematic review aimed to identify, describe, and categorize noise sources in the NICU and to examine their potential impact on preterm infants. Method: A systematic search across six major databases [MEDLINE, Embase, APA Psychinfo, CINHAL, Scopus, Web of Science (WOS); 2000-2026] identified studies reporting 24-h noise levels, day-night variation, and differences between incubator-internal and external sound. Eligible studies were synthesized and visualized using forest, strip, and dot plots, interpreted relative to American Academy of Pediatrics (AAP) recommendations. Result: From 113 included studies, most reported sound levels substantially above recommended limits. Alarms, staff conversations, and incubator-associated equipment were consistently identified as major contributors. Respiratory support devices produced the highest internal noise levels, at times exceeding overall NICU ambient noise. Interventions such as staff training, behavioral adjustments, and environmental modifications yielded short-term improvements but rarely produced sustained reductions. Conclusion: NICU noise is a modifiable risk factor with significant developmental implications. Future strategies should integrate environmental design, technological innovation, and infant-focused interventions at the incubator-device interface to create safer, developmentally supportive acoustic conditions. Evidence also suggests that excessive shielding may reduce meaningful auditory input, raising concerns about potential auditory deprivation.