White noise is recognized as a calming and sleep-enhancing sensation. In the womb, babies are
exposed to multiple noises from maternal physiologic sounds, including the voice of the mother
and the constant, rhythmic murmur from blood flow through uterine, umbilical, and placental
vessels. Intrauterine sound levels have been measured at 72-95 dB.2,3
Infant care providers have long recognized the benefit of sound. They routinely shush loudly
(~95 dB) to calm fussing and shush softly (~70 dB) to lull babies into sleep. Studies of baseline
sound in NICUs have demonstrated average levels of 60-89 dB in the room and levels that were
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1 Centers for Disease Control & Prevention, (2003) “Guidelines for Environmental Infection Control in Health-Care
Facilities”, available at: https://www.cdc.gov/infectioncontrol/guidelines/environmental/background/laundry.html
2 Smith CV, Satt B, Phelan JP, et al. (1990) “Intrauterine sound levels: Intrapartum assessment with an intrauterine microphone.” Am
J of Perinat; 7: 312-315, doi: 10.1055/s-2007-999511.
3 Walker D., Grimwade J., & Wood C. (1971), “Intrauterine noise: A component of the fetal environment. Am J of Obgyn, 09(1):91-5.
doi: 10.1016/0002-9378(71)90840-4
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8 dB higher in the isolette.4 These sound levels were found to have no negative physiologic
responses in the infant experiencing intermittent acoustic events in the NICU.5 In fact, the
white noise used by SNOO has even been shown to reduce hypoxemic and bradycardic events
and stabilize breathing and cardiac control in preterm infants.
SNOO’s white noise is specifically engineered to soothe infants by mimicking in-utero sounds.
The sound on the blue baseline level is around 68dB measured at the baby’s ear and its highest
volume at the orange level is approximately 85 dB, which is significantly less intense than a
baby’s own cries.
Clinicians who prefer to reduce the noise can do so in the “Settings” tab of the SNOO app by
choosing the lowest sound intensity. The normal level can be reduced to around 55dB.