How Loud Should a Baby Sound Machine Be?
The 50 dB rule, explained — and the one detail most sites (and most machines) get wrong.
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.
Where the 50 dB number comes from
In 2014, researchers tested 14 commercially available infant sleep machines and published the results in Pediatrics, the American Academy of Pediatrics' own journal. They measured each machine at three distances — 30 cm, 100 cm, and 200 cm — and compared the results against 50 dBA, the noise-level limit recommended for hospital nurseries. Every single machine they tested exceeded that limit at 30 cm, and 3 of the 14 exceeded 85 dBA — a level that, sustained over a full night, matches adult occupational noise-exposure limits (the kind used to set workplace hearing-protection rules).
The detail most guidance gets wrong
50 dB is a target for what reaches your baby's ear — not what the machine outputs at its speaker, and not what you hear standing across the room. Sound intensity drops off sharply with distance, so a machine that reads 50 dB on a phone app held next to it can be significantly louder right where your baby's head actually is if it's placed too close. That's the gap the 2014 study was specifically measuring.
How to actually check
- Use a free sound-meter app on your phone, held at the approximate position of your baby's ear in the crib — not at the machine itself.
- Aim for around 50 dB — roughly the loudness of a quiet conversation or a running refrigerator.
- If you can't easily measure it, err toward quieter and farther away rather than louder and closer — there's no evidence that louder produces better sleep.
For placement specifics, see how far the machine should be from the crib.
Why hushnap can't do this measurement for you
A volume slider in a web app controls the signal we generate — it has no way to know how loud your actual speaker plays that signal, or how far away your baby is. That's why our player shows a gentle reminder at high volume settings instead of a fake decibel readout: a number we can't actually verify would be more misleading than no number at all.