Keep a baby’s white noise machine at or below about 50 dBA, measured where the baby’s head is. That’s the noise limit for hospital nurseries used as the benchmark in the main study of infant sleep machines. In practice that means the lowest volume that does the job, with the machine across the room from the crib rather than on the rail or in the bassinet.
It matters because many machines are far louder than parents realize. In that study, every machine tested exceeded 50 dBA at close range, and some could exceed 85 dBA at full volume.
What did the infant sleep machine study find? #
In 2014, researchers at the Hospital for Sick Children in Toronto published a study in Pediatrics (Hugh et al., “Infant sleep machines and hazardous sound pressure levels”). They tested 14 infant sleep machines at maximum volume, measuring at 30 cm, 100 cm and 200 cm from each device, the kind of distances you get with a machine on the crib rail, near the crib, or across the room.
What they found:
- All 14 machines exceeded 50 dBA at 30 cm. 50 dBA is the recommended noise limit for infants in hospital nurseries, the benchmark the researchers used.
- Three machines exceeded 85 dBA at maximum volume. 85 dBA is the level at which NIOSH’s workplace limit allows adults 8 hours a day.
- The authors concluded that these devices can produce sound levels that may be damaging to infant hearing and auditory development, and they recommended ways to operate them more safely.
Most parents don’t run a machine at maximum, and a baby isn’t exposed like a factory worker. But babies may hear the machine for 10 or more hours a day, their ears and auditory systems are still developing, and they can’t move away or complain. Erring on the quiet side makes sense.
How loud should a white noise machine be for a baby? #
Aim for these practical targets:
| Setting | Target |
|---|---|
| Level measured at the baby’s head | 50 dBA or lower |
| Machine distance from the crib | As far as practical; across the room, not on the rail |
| Volume | The lowest setting that masks the noise you’re trying to cover |
| Timer | Consider switching it off or down once the baby is deeply asleep |
A rough ear check: if you have to raise your voice to talk over the machine while standing next to the crib, it’s too loud. At 50 dBA, a normal conversation (60 to 70 dBA) is clearly louder than the machine.
How does distance change the level? #
Distance is your best tool. In open space, sound drops about 6 dB each time you double the distance from the source:
| Machine distance from baby | Approximate change vs 30 cm |
|---|---|
| 30 cm (on the crib rail) | reference |
| 60 cm | about 6 dB quieter |
| 1.2 m | about 12 dB quieter |
| 2.4 m (across a small room) | about 18 dB quieter |
A machine that reads 68 dB at 30 cm could be near 50 dB at 2.4 m. In a real bedroom, reflections off walls mean you won’t get the full drop, so measure rather than assume. More in sound level vs distance.
How do you measure a white noise machine’s volume at home? #
A phone sound meter does this well enough. You’re checking whether you’re near 50 or near 70, not certifying to the decibel.
- Turn on the machine at the volume you normally use.
- Place your phone where the baby’s head lies, microphone uncovered, facing up.
- Set the meter to A-weighting (dBA), and step away so you’re not blocking or adding sound.
- Measure for 30 seconds and read the average (Leq).
- Adjust the volume or the machine’s position, then measure again.
Sound Meter dB makes this a one-minute check. Tap Start, set the phone at the crib, and read the Leq on the stats row. The dial shows the zone at a glance: 45 to 60 dB is “Moderate,” and anything in the orange 70s is clearly too loud for a nursery. If you want a record, sessions of 10 seconds or more are saved on the phone. The app analyzes sound on the device and doesn’t record or upload audio, which matters to many parents in a nursery.
Phone microphones aren’t calibrated instruments, so treat a reading of 49 versus 52 as “about 50.” See how accurate phone sound meters are.
Is white noise good for babies at all? #
Many parents find steady sound helps babies settle and covers household noise such as siblings, traffic or a TV. There’s nothing wrong with using it at a sensible level. The research concern is about loud machines placed close to the baby for long periods, not about white noise itself.
A few extra points:
- Check the maximum volume. If the machine goes very loud, a child or visitor can turn it up by accident. Some parents tape over the volume control once they’ve set it.
- Sound machines built into toys or crib mobiles sit right next to the baby’s head. Measure those especially.
- Apps on a phone or smart speaker can be as loud as a dedicated machine. The same distance and volume rules apply.
- Rest time matters. Quiet periods during the day are good for anyone’s ears.
For broader guidance on children and noise, see how loud is too loud for kids, and for adult bedrooms, safe noise level for sleeping.
What are the signs a baby’s hearing needs checking? #
Most babies in the U.S. and many other countries get a newborn hearing screening. After that, talk to your pediatrician if your baby doesn’t startle at loud sounds, doesn’t turn toward voices as they grow, or isn’t babbling or responding to their name at the usual ages. Only a professional can assess a baby’s hearing, and early checks make a real difference.
Frequently asked questions #
How many decibels should a white noise machine be for a baby? #
About 50 dBA or less at the baby’s head, based on the hospital nursery limit used in infant sleep machine research. Place the machine across the room and use the lowest volume that works.
Is it safe to leave a white noise machine on all night for a baby? #
Many parents do, and at a low level placed away from the crib it’s generally considered reasonable. The concern is loud machines close to the baby for many hours. If you’re unsure, use a timer or lower the volume after the baby falls asleep, and ask your pediatrician.
Can white noise damage a baby’s hearing? #
At high volume and close range, it could. The 2014 Pediatrics study found some machines could exceed 85 dBA at full volume. At a modest level measured around 50 dBA at the crib, the risk is low. Distance and volume are what matter.
Is a fan safer than a white noise machine? #
Not automatically. A fan is another steady noise source, and some are quite loud up close. Measure at the crib either way, and keep any fan out of the baby’s reach.