Heartbeat and Womb Sounds for Infants: What Studies Show
These two sounds have more specific research behind them than most of the other options on this site — mostly from NICU care.
This is general information for a parenting/consumer audience, not medical advice. It doesn't replace guidance from your pediatrician, and every baby is different.
Heartbeat sound
Studies combining a mother's heartbeat sound with white noise, largely conducted in neonatal intensive care settings, have reported improved cardiorespiratory stability and feeding outcomes in premature infants. Heartbeat sound has also been shown to reinforce learned responses in newborns in earlier research. This is a genuinely specific evidence base — not just "soothing sounds in general" but heartbeat sound studied on its own.
Womb / intrauterine sound
Real intrauterine recordings are surprisingly loud — a 2018 study externally recording womb sounds during pregnancy found levels of roughly 70–90 dB, exceeding current NICU sound recommendations by 10 to 30 dB. That's louder and more variable than most people picture "the womb" sounding. The same research found womb-like sound may help with cardiorespiratory stability, pain mitigation, and sleep promotion in infants, and other studies using simulated intrauterine sound have found it can reduce infants' pain response during medical procedures. That evidence is strongest for preterm infants in clinical contexts, not necessarily for healthy full-term babies at home — but it's a real, specific research thread.
An honesty note about our "Womb" sound
hushnap's Womb tile is synthesized in the browser — filtered noise shaped to be inspired by what research on intrauterine sound describes, not a recording of an actual womb. That distinction matters: the same 2018 study found that commercially available "womb sound" products generally differ significantly from real recorded womb sounds, tending to be dominated by generic broadband noise and missing the bowel sounds that characterize real intrauterine acoustics. We'd rather say that plainly than imply our synthesized tile carries the same authenticity as an actual recording.
Practical takeaway
Of all the sounds on this site, heartbeat and womb sound have some of the most direct research support — worth trying first if you want an evidence-informed starting point, though as with everything here, which sound actually settles your baby comes down to individual preference.
- Parga JJ, Daland R, Kesavan K, Macey PM, Zeltzer L, Harper RM. "A description of externally recorded womb sounds in human subjects during gestation." PLoS One, 2018.
- Studies of maternal heartbeat sound combined with white noise on cardiorespiratory and feeding outcomes in preterm infants (NICU settings).