title: Questionable sound exposure outside of the womb: frequency analysis of environmental noise in the neonatal intensive care unit.
abstract: OBJECTIVE
  Recent research raises concerns about the adverse effects of noise exposure on the developing preterm infant. However, current guidelines for NICU noise remain focused on loudness levels, leaving the problem of exposure to potentially harmful sound frequencies largely overlooked. This study examined the frequency spectra present in a level-II NICU.
  
  
  METHODS
  Noise measurements were taken in two level-II open-bay nurseries. Measurements were taken over 5 days for a period of 24 h each. Spectral analysis was focused on comparing sound frequencies in the range of human speech during daytime (7 AM-7 PM) vs. night-time (7 PM-7 AM).
  
  
  RESULTS
  On average, daytime noise levels (Leq = 60.05 dBA) were higher than night-time (Leq = 58.67 dBA). Spectral analysis of frequency bands (>50 dB) revealed that infants were exposed to frequencies <500 Hz 100% of the time and to frequencies >500 Hz 57% of the time. During daytime, infants were exposed to nearly 20% more sounds within the speech frequency range compared with night-time (p = 0.018).
  
  
  CONCLUSIONS
  Measuring the frequency spectra of NICU sounds is necessary to attain a thorough understanding of both the noise levels and the type of sounds that preterm infants are exposed to throughout their hospital stay. The risk of high-frequency noise exposure in the preterm population is still unclear and warrants further investigation.
authors.affiliation: Department of Pediatrics and Newborn Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Pediatrics, MassGeneral Hospital for Children, Harvard Medical School, Boston, MA, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Lahav
mesh_terms: D000162:Acoustics; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data*; D009622:Noise
keywords: Environment; Frequency; NICU; Noise; Preterm infants