title: Octave waveband analysis to determine sound frequencies and intensities produced by nebulizers and humidifiers used with hoods.
abstract: BACKGROUND
  health-care practitioners should be aware of how their equipment and practices can increase the patient's risk for noise-induced hearing loss.
  
  
  OBJECTIVE
  We conducted this study to determine the type of noise produced by humidifiers and nebulizers used with hoods in the neonatal intensive care unit (NICU). We performed octave waveband analysis to determine sound intensities and frequencies because degree of hearing loss from noise exposure is related to the intensity of sound, frequency of sound and duration of exposure.
  
  
  METHODS
  We studies 4 simple humidifiers, 3 heated humidifiers, and 4 nebulizers. Sound levels were measured at various frequencies, flows, and water levels using Peace and Shiley oxygen hoods.
  
  
  RESULTS
  The findings show that sound levels were significantly louder (p.0.001) for nebulizers compared to humidifiers. Aquapak nebulizers pose the greatest risk for hearing loss because they produce sound at the highest frequencies and volumes. The peak sound levels of humidifiers not only were significantly lower but also occurred at the lowest sound frequencies, which are the least damaging to hearing. Sound levels were generally higher across sound frequencies at higher flows and with the Peace Hood.
  
  
  CONCLUSIONS
  We conclude that heated humidifiers produce lowest sound intensities at the lowest sound frequencies and, consequently, are most appropriate for use in the NICU.
authors.affiliation: Department of Respiratory Therapy, Medical College of Georgia, Augusta 30912, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Mishoe
authors.forename: C W
authors.initials: CW
authors.lastname: Brooks
authors.forename: F H
authors.initials: FH
authors.lastname: Dennison
authors.forename: K V
authors.initials: KV
authors.lastname: Hill
authors.forename: T
authors.initials: T
authors.lastname: Frye
mesh_terms: D004781:Environmental Exposure; D005845:Georgia; D006272:Health Facility Environment; D006317:Hearing Loss, Noise-Induced / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000209:etiology; D007186:Incubators, Infant / Q000009:adverse effects; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D009330:Nebulizers and Vaporizers / Q000592:standards*; D009623:Noise, Occupational / Q000009:adverse effects*; D012307:Risk Factors; D012892:Sleep Deprivation; D014481:United States; D012122:Ventilators, Mechanical / Q000009:adverse effects*