The Nightstand · runs in your browser

White Noise for Babies

White, pink and brown noise generated right here in your browser, with a volume you can actually keep low and a timer that fades out rather than stopping dead. It comes with the volume and distance guidance attached, because the only measurement anybody has published on these machines is not reassuring.

No account, no email, and nothing you type is sent anywhere.

30:00
Ready. It will not make a sound until you press play — nothing on this page starts on its own.
Which noise White noise carries the same energy at every frequency, so the high end dominates and it sounds like static. Nobody has measured which of the three settles a baby best, so the honest way to choose is to play each one quietly and see.
Timer On by default, and it fades out over the last half-minute rather than stopping dead. The concern in the published measurements is accumulated exposure across a whole night, not a loud moment — a timer that covers the settling sidesteps the question entirely.
The one measurement anybody has published

Fourteen sleep machines, measured at three distances.

Researchers played 14 infant sleep machines at maximum volume and measured them at 30, 100 and 200 centimetres, correcting for a six-month-old’s ear canal. It is the only study of its kind, it was published in a paediatric journal, and this is what it found.

At 30 cm, every one
above 50 dBA

All fourteen exceeded 50 A-weighted decibels at thirty centimetres — the recommended noise limit for infants in hospital nurseries. Thirty centimetres is roughly a machine sitting on the cot rail.

Three of the fourteen
above 85 dBA

At that level, sustained for more than eight hours, the exposure exceeds the accumulated-noise limits set for adults at work and carries a risk of noise-induced hearing loss.

What the authors concluded
Distance and duration

The paper concludes these machines can produce levels that may be damaging to infant hearing and auditory development, and sets out recommendations for safer operation. Nobody can tell you it is harmless at any setting.

Read plainly, the levers you have are the three the study varied: how loud, how far away, and how long. Never on or in the cot, never at maximum, across the room rather than beside her, and for the settling rather than the whole night. The NHS’s own phrasing for what may help a crying baby is gentle noise in the background, alongside holding her close, moving gently and a warm bath — and gentle is doing real work in that sentence.

What this is, and what it is not. A noise generator, running on your own device, with the guidance attached rather than buried. It estimates nothing about your baby and it cannot hear your room: the volume control is a proportion of whatever your device is already set to, so the same position on that slider is a different sound in every house. That is why the range is labelled in words and why no decibel figure appears anywhere on this page — printing one would be inventing it.

What the evidence does and does not say. The NHS lists gentle background noise among the things that may help distract a crying baby, which is a far more modest claim than this category makes for itself, and crying tends to peak around two weeks and settle by about three months on its own — so anything introduced at six weeks will look more effective than it was. On the other side, the single published measurement of these machines is a caution rather than a clearance. Nobody has shown a level that is definitely safe for a whole night, and this page will not pretend otherwise.

Safe sleep decides where the sound goes. A speaker, a phone or a machine never goes in the cot, on the cot rail or under the mattress. Babies sleep on their back, on a firm flat surface, in a cot clear of blankets, pillows, bumpers, soft toys and cables, in your room for at least the first six months, with nothing weighted on or over them. If your baby is inconsolable, hard to rouse, feeding poorly, or her cry does not sound like her usual one, that is a call to your pediatrician or health visitor rather than a settling problem — and none of this is medical advice.

How this is worked out

  1. The sound is generated rather than played. Your browser fills a few seconds of audio buffer with random numbers and loops it, so there is no file to download, nothing is streamed while it runs, and no recording anybody owns is involved. It works with the network off.
  2. White noise is the raw random signal, with equal energy at every frequency, which is why it sounds bright and hissy. Pink noise is the same signal with the high frequencies rolled off so that energy falls as the frequency rises — it is the deeper, rainfall-like one. Brown noise rolls them off harder still and sounds like a distant engine. Which one settles a particular baby is not something anybody has measured; try them.
  3. Nothing starts on its own. The audio engine is only created when you press play, because a page that begins making noise by itself is a page that wakes the baby you just put down — and because browsers block it anyway.
  4. The volume slider is labelled in words rather than decibels, deliberately. This page has no idea how loud your room actually is: your device volume, your speaker, the distance to the cot and the walls all sit between this slider and your baby's ear, and none of them is visible to a web page. Anybody printing a decibel number here would be inventing it.
  5. The timer counts down on the ring and fades the sound out over the last thirty seconds instead of cutting it, which is both gentler and the pattern that lets the room go quiet for the rest of the night. It is set on by default, because the published measurement is about accumulated exposure over hours rather than about a moment.
Questions

The short answers

The honest answer is that it depends entirely on how loud and how close, and that the one study anybody has published is a caution rather than a clearance. Researchers measured 14 infant sleep machines at maximum volume and found every one of them above 50 A-weighted decibels at 30 centimetres, which is the recommended noise limit for infants in hospital nurseries, and three above 85 A-weighted decibels — a level that, sustained for more than eight hours, exceeds the accumulated-noise limits set for adults at work and carries a risk to hearing. The paper concludes that these machines can produce levels that may be damaging to infant hearing and auditory development, and sets out recommendations for safer operation. Nobody can tell you it is harmless at any setting.
As quiet as does the job, and as far away as the room allows. The measurements in that study were taken at 30, 100 and 200 centimetres precisely because distance is the lever you have: the same machine is a very different exposure across the room from what it is on the cot rail. In practice that means never on or in the cot, never at maximum, on for the settling rather than for the whole night, and a level you can comfortably talk over from where you are standing. The NHS's own phrasing for what helps a crying baby is gentle noise in the background, and gentle is doing real work in that sentence.
For some babies, apparently, and the evidence is thinner than the marketing. The NHS lists having some gentle noise in the background among the things that may help distract a crying baby, alongside holding them close, moving gently and a warm bath — which is a considerably more modest claim than the category makes for itself. It is also worth knowing that crying tends to rise to a peak around two weeks and settle down again by about three months on its own, so a machine introduced at six weeks will often look far more effective than it was.
How the energy is spread across the frequencies. White noise has the same energy everywhere, so the high frequencies dominate what you hear and it sounds like static or a television between channels. Pink noise drops the energy off as frequency rises, which sounds like steady rain or a river. Brown noise drops off twice as fast again and sounds like a distant engine or surf a long way away. There is no published finding that any of the three works better for a baby than the others, so the sensible way to choose is to play each one quietly and see which one your household can stand.
This page defaults to a timer rather than to all night, and the reason is exposure. The concern in the published measurements is not a loud moment, it is a level sustained for hours — the 85-decibel figure only becomes an occupational problem when it runs past eight hours. A timer that covers the settling and then fades out sidesteps that question entirely, and it avoids the separate practical problem of a baby who has learned she cannot fall back to sleep without it. If you do want it running longer, the answer is to move the machine further away and turn it down, in that order.
Your chosen sound, volume and timer are saved in this browser under one key, so the player opens the way you left it. There is no account, no server involved and no request carries anything anywhere — the noise itself is made on your own device. The Clear button under the player forgets all of it.

Where this comes from

  1. Pediatrics (PubMed) (2014). Infant sleep machines and hazardous sound pressure levels. https://pubmed.ncbi.nlm.nih.gov/24590753/
  2. NHS (2026). Soothing a crying baby. https://www.nhs.uk/baby/caring-for-a-newborn/soothing-a-crying-baby/
  3. American Academy of Pediatrics (HealthyChildren.org) (2024). Getting Your Baby to Sleep. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/getting-your-baby-to-sleep.aspx
  4. American Academy of Pediatrics (HealthyChildren.org) (2022). How to Keep Your Sleeping Baby Safe: AAP Policy Explained. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/A-Parents-Guide-to-Safe-Sleep.aspx
  5. NHS (2025). Reduce the risk of sudden infant death syndrome (SIDS). https://www.nhs.uk/baby/caring-for-a-newborn/reduce-the-risk-of-sudden-infant-death-syndrome/

Every link above was opened and read when this page was last updated. Snuggle is not affiliated with any of these organisations and none of them has reviewed this page. Nothing here is medical advice.

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The app this site is for

Snuggle does this with your baby’s own pattern.

This page works from an age band, because an age band is all a web page knows about you. Snuggle starts from the same bands and then blends them with what your baby actually did today — how long she lasted, when she went down, how the last nap ran — and shows on the face of the ring how sure it is. Early estimates say they are early.

It logs sleep, feeds, nappies and growth in one tap on a dim red screen, and every caregiver in the household is on the same timeline in their own account. The arithmetic runs on the phone, on your baby’s own history. There are no AI features in it.

In development for iPhone and Android. Not released yet — when it is, it will be on this site.

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