How Far Should a Sound Machine Be From the Crib?
You'll see '7 feet' everywhere. Here's what was actually tested, and why the honest answer is slightly less precise than that.
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.
What was actually tested
The 2014 Pediatrics study on infant sleep machines measured sound output at three distances: 30 cm, 100 cm, and 200 cm (about 12 in, 3.3 ft, and 6.6 ft). Even at the farthest distance tested — 200 cm — some machines still measured above the 50 dBA nursery-noise limit. The study didn't test beyond 200 cm, so it doesn't tell us exactly how far away is definitely safe for every machine at every volume.
Where "7 feet" comes from
Many parenting and pediatric sites round the study's farthest tested distance (200 cm ≈ 6.6 ft) up to "at least 7 feet" as a simple rule of thumb. That's a reasonable, conservative rounding of the real data — but it's a popularization, not a verbatim recommendation from the study itself or a specific AAP policy number. We're flagging that distinction because a lot of sites present it as a direct quote when it isn't one.
Practical takeaway
- Place the machine at least 2 meters (about 7 feet) from the crib as a starting point, not on the crib rail or inside it.
- Distance and volume trade off against each other — if you can't get that far away, turn the volume down and check the actual sound level near your baby's ear instead.
- See how loud is safe for how to check.