You've heard the numbers: keep it at 50 dB. No, 60. Actually, some experts say 70 is fine. Which one is right? If you've Googled this before, you've probably walked away more confused than when you started. Let's settle this properly: with the actual studies, not opinions. Also read our guides on whether white noise helps babies sleep and comparing noise colours.
In 2014, Hugh and colleagues published a study in Pediatrics, with Papsin as senior author. It was not an American Academy of Pediatrics (AAP) study, and the AAP did not run it. The researchers measured the maximum sound levels of 14 infant sleep machines at 30 cm, 100 cm and 200 cm. All 14 exceeded 50 dBA at 30 cm, and three exceeded 85 dBA at 30 cm. The 50 dBA figure they compared against is an average of 50 dBA over one hour, the recommended noise limit for infants in hospital nurseries, not an instant ceiling. The study did not set a 50 dBA home limit and did not set a 2 metre rule.
Dr. Harvey Karp (author of The Happiest Baby on the Block) recommends 55–70 dB, which is louder than the 50 dBA one-hour average used for hospital nurseries. His reasoning: the womb is roughly 75–90 dB loud, so babies are wired to calm at higher volumes. This is true: the womb IS loud. But the womb is also muffled by amniotic fluid and tissue, and exposure is 24/7 for 9 months, not 12 hours overnight for years. The 50 dBA one-hour average is based on hearing safety over time, which is the more relevant measure for nightly use.
Our recommendation: Aim for an average of 50 dBA over one hour at the cot, not Dr. Karp's 70 dB. The 50 dBA benchmark is based on audiology research and hearing damage risk. Louder white noise may work faster, but it's not worth the long-term risk to your baby's hearing.
Red Nose Australia sets no volume limit for white noise. Its safe sleep guidance includes principles that apply directly:
Red Nose's focus is on preventing SIDS and fatal sleep accidents, not hearing damage. That's why its guidance covers cords and the sleep environment rather than decibels. The 50 dBA one-hour average and the 2 metre placement are practical steps, not Red Nose rules, and they sit alongside the cord-safety advice.
Distance is the most useful practical lever, and the one most parents get wrong. Sound intensity drops by about 6 dB every time you double the distance. The table below is an illustrative model, not a set of measurements.
Assumptions: the model starts from 65, 75 and 85 dB at 30 cm for the 50%, 75% and 100% settings, then applies a 6 dB drop per doubling of distance. Real machines vary, and room surfaces change the result. Use it to see the pattern, then check your own setup with a meter.
| Illustrative setting | At 30 cm (next to cot) | At 1 metre | At 2 metres |
|---|---|---|---|
| Set to 50% | ~65 dB ⚠️ | ~53 dB ⚠️ | ~47 dB ✅ |
| Set to 75% | ~75 dB 🚫 | ~63 dB ⚠️ | ~57 dB ⚠️ |
| Set to 100% | ~85 dB 🚫 | ~73 dB 🚫 | ~67 dB 🚫 |
In this model, a machine at 50% volume 2 metres away lands near the 50 dBA one-hour average. That is the point: distance matters as much as the volume dial. A powerful machine at 100% can still be too loud at 2 metres.
You don't need special equipment. Download a free decibel meter app:
Then test like this:
Quick at-home test without an app: Stand next to the cot with the machine running. If you can hold a normal conversation without raising your voice, the volume is likely safe. If you have to speak up, turn it down. This isn't precise but it's better than guessing.
Yes, if played too loud or too close. Babies' ear canals are smaller and narrower than adults', which means they amplify sound more. A 2024 study published in ScienceDirect found that some white noise machines produce up to 91 dB at close range: equivalent to a motorcycle engine.
The damage is cumulative. A single night at 70 dB won't cause hearing loss. But 70 dB every night for 2 years adds up. Hearing damage from noise exposure is often gradual and permanent: by the time you notice a problem, the damage is done.
Babies' hearing sensitivity changes as they grow. The ranges below are practical targets, not measured age-specific limits.
| Age | Practical target | Distance | Notes |
|---|---|---|---|
| 0–3 months | 45–50 dB | 2 metres | Most sensitive period; keep it as low as practical |
| 3–12 months | 50 dB | 2 metres | Practical target |
| 12–24 months | 50 dB | 1.5–2 metres | Same practical target, slightly less strict on distance |
| 2+ years | 50–55 dB | 1.5 metres | Keep the same practical target where possible |
Bottom line: An average of 50 dBA over one hour at 2 metres is a practical target for all ages. If you remember one number, that's the one. Read our guide on weaning off white noise when you're ready to phase it out.
The recommended limit for infants in hospital nurseries is an average of 50 dBA over one hour, which is about the volume of a quiet conversation or gentle rainfall. It is an average, not an instant ceiling. Every machine in the 2014 Hugh et al. study exceeded 50 dBA at maximum volume at 30 cm, so never use full power. Start at the lowest volume that helps your baby settle, and place the machine 2 metres from the cot as a practical step.
An average of 50 dBA over one hour measured at the cot is the recommended limit for infants in hospital nurseries. Some hospital settings use lower benchmarks. The 55–70 dB range suggested by some sources is not supported by audiology research for continuous overnight exposure. When in doubt, quieter is safer.
Yes. Some machines can produce 91+ dB at close range. Sustained exposure above 70 dB can cause gradual, permanent hearing loss. Babies' smaller ear canals amplify sound, making them more vulnerable than adults. The damage accumulates over time: a few loud nights won't hurt, but months of loud white noise can.
Place the machine at least 2 metres from the cot as a practical step. Neither the 2014 study nor Red Nose Australia sets this distance. Distance matters because sound drops by about 6 dB every time you double it: a machine at 70 dB right next to the cot drops to about 50 dB at 2 metres.
See the white noise machines covered in our Australian comparison.
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