Brown Noise for Babies

What Researchers Measured From Infant Sleep Machines

In 2014, a team in the ear, nose and throat (head and neck surgery) department at the University of Toronto tested fourteen infant sleep machines. They set each one to full volume and measured how loud it was. The paper is Hugh, Wolter, Propst, Gordon, Cushing and Papsin, Infant Sleep Machines and Hazardous Sound Pressure Levels (Pediatrics, 2014;133(4):677–681). It is short and specific. If you read one thing before you put a sound machine in a nursery, read this.

They measured at three distances: 30, 100 and 200 cm. They also adjusted the results for the ear canal of a six-month-old baby, which is not the same as an adult's.

Every one of the fourteen machines was louder than 50 decibels at 30 cm. All of them. That limit is not random. 50 decibels, about as loud as a quiet office, is the recommended noise limit for babies in hospital nurseries. So every machine, at full volume and at cot-side distance, was louder than the level thought acceptable for a baby in a hospital.

Three of the machines were louder than 85 decibels, about as loud as heavy traffic. At that level, played for more than eight hours, the total noise goes over the limits set for adults at work. Those limits were written for adult ears over a working day, not for a baby's still-developing hearing overnight.

The authors' conclusion is careful and worth reading as written: these machines can produce sound levels that may damage a baby's hearing and hearing development. The paper then sets out advice for safer use. Note what the concern is. It is not whether the sound is white, brown or pink. The concern is volume, distance and time: the three things the study looked at, and the three things you control.

The Three Controls That Matter, in Order

1. Distance does more than the volume button. Sound gets quieter as you move away from it, and in the open it drops fast: about 6 decibels each time you double the distance. A small room bounces sound back, so the drop is smaller there. In practice, moving a device from the cot rail to the other side of the room is the biggest cut you can make. It needs no guesswork about levels, and a knock to the volume button cannot undo it. Put the sound source as far from the cot as the room allows, pointing at the door or a wall, not at the baby.

2. Volume: set well below full, and checked at the cot. The measurements above were at full volume, which no one should use. Whatever level you choose, judge it standing where the baby's head will be, not from the doorway. A rough rule many clinicians share: the sound should be quieter than a normal speaking voice. If you have to raise your voice to be heard over it at the cot, it is too loud. Free phone sound-meter apps are not exact, but they can reliably tell roughly 50 decibels from roughly 80 decibels. That is the difference that matters here.

3. Time, because total exposure is volume multiplied by time. The 85-decibel finding above used an eight-hour limit for a reason: the same volume adds up to more over a longer time. A device that runs from bedtime to morning gives many times the exposure of one that fades out after the baby is asleep. Here a timer is not a nice extra. It is the third control.

None of these three is special to brown noise. They apply to any sound machine, any app, any phone and any colour of noise.

Nothing Goes In or On the Cot

There is a second kind of safety here that has nothing to do with hearing, and it comes before everything else on this page.

The American Academy of Pediatrics' 2022 recommendations for reducing sleep-related infant deaths (Moon, Carlin and Hand, Pediatrics 2022;150(1):e2022057990) describe a safe sleep setup. It includes putting the baby to sleep on their back, a firm and flat (not tilted) sleep surface, sharing a room but not a bed, and no soft bedding or overheating.

A phone, a cable, a soft toy sound machine, a speaker or a monitor clipped to the rail does not belong in that picture. Whatever you use to make sound, put it on a surface away from the cot. Keep any cable where the baby cannot reach it. That is the same place the hearing evidence points to. The two safety rules agree, which makes it simple: the sound source goes across the room, and the cot holds the baby and nothing else.

If you use a phone, put it face down on a shelf on the far side of the room, well out of reach of the cot. Remember that a phone also makes notification sounds and light unless you turn both off.

There Is No Evidence Brown Noise Is Better for Infants

This site makes brown noise, and it would be easy to tell you it is the gentler, safer, more womb-like choice for a baby. Nothing published supports that, so this page will not say it.

What we can say is what is physically true. Most of brown noise is deep sound, and it gets steadily quieter as the pitch goes up. So at the same overall volume it has much less high, hissy sound than white noise. Nobody has studied whether that difference matters for a baby's hearing at the modest volumes this page suggests. The 2014 study found problems with volume and distance across a whole group of machines, whatever sound they made. That is a strong hint about where the real risk is.

There is also a practical point that works the other way. Small speakers and phone speakers cannot play deep sounds well, so brown noise through them sounds thin and quiet. The natural fix is to turn the volume up, which makes everything the speaker can play louder. That is how a nursery gets louder by accident. If a small speaker is what you have, a colour with more middle-range sound will give you the same feel at a lower setting.

Popular claims that one colour sounds like the womb, or that a certain pitch naturally soothes newborns, are not supported by anything this page can cite. Treat them as marketing.

Does It Help Babies Sleep? The Evidence Is Weaker Than You Would Expect

Sound machines are now in so many nurseries that the state of the evidence is truly surprising.

The key review is Riedy, Smith, Rocha and Basner, Noise as a sleep aid: A systematic review (Sleep Medicine Reviews, 2021). It looked at 38 articles on steady noise as a sleep aid. Its conclusion goes against what most people believe. The quality of the evidence that steady noise improves sleep was judged very low, and the authors note that this does not match how widely it is used. They also raise the possibility that steady noise may harm sleep and hearing.

That review was not only about babies, and it did not look at brown noise on its own. But it is the best summary available on the basic question, and it does not support the claim that a sound machine will improve a baby's sleep. Anyone who says this is proven has not read it.

What is not in doubt is how covering sound works. This is called sound masking: covering one sound with a steadier one, so the brain stops noticing it. A steady sound makes a door closing, a car outside or a sibling on the stairs less likely to stand out. If your problem is that your baby wakes when the house makes a noise, masking is a real effect, and brown noise suits the deep, rumbling end of it. That is a much narrower claim than "helps babies sleep", and it is the only one this page makes.

Whether to use sound at all, and how, is a fair thing to raise at a routine appointment. This matters most for a newborn, a premature baby, or a baby with any hearing concern or who has not yet passed a hearing screen.

Reasons to Stop and Ask a Paediatrician

Stop using the sound and get advice if your baby has any fluid coming from the ear, seems to have ear pain, or seems to react less to sounds or voices than before. Do the same if a hearing screen was missed, failed or is still to be done.

Do not use sound to settle a baby who seems unwell, who is crying in a way that is unusual for them, or whose distress is getting worse instead of easing. Masking sound covers noise; it does not fix a cause. A baby who cannot be comforted is a reason to speak to a clinician, not to reach for the volume.

Be careful about turning it up. If the level that used to settle your baby no longer works, the answer is not a higher setting, because the safety findings above are all about volume. That is the point to change something else, or to ask for help.

For a premature or low-birthweight baby, or any baby under specialist care, ask before you start, not after. Nursery noise limits exist because a baby's still-developing hearing is exactly what those limits were written to protect.

What a Timer and a Fixed Volume Are Actually For

The player at the top of this page makes brown noise live in your browser, not from a recording. So there is no loop point, and nothing clicks or restarts. Free web sessions run for 30 minutes.

For a nursery, the useful features are the boring ones, and they match the three controls above. A sleep timer limits the time, which is the control most people ignore. Offline playback means no ads, no notifications and no internet problems to interrupt at two in the morning. Background playback means the sound does not stop when the screen locks. The free app does all three and removes the session limit.

Two things it does not do, on purpose: claim to improve baby sleep, or recommend a volume for you. It is a sound player with a timer. Placing it across the room, setting the volume at the cot, and deciding whether to use it at all are your choices. They are worth discussing with your child's doctor.

Medical Disclaimer

The information on this website is provided for general educational purposes only and is not medical advice. Brown noise and other sound therapies are not a diagnosis, treatment, or cure for any medical condition, including insomnia, tinnitus, ADHD, or any hearing or sleep disorder.

Always consult a qualified healthcare professional — such as your doctor, an audiologist, or your child's pediatrician — before relying on sound therapy for a health concern, and especially before using it with infants or anyone with existing hearing sensitivity. Never disregard or delay professional medical advice because of something you have read here.

Individual results vary. Any research referenced on this page describes general findings and does not guarantee a particular outcome for you. If you experience discomfort, ear pain, worsening symptoms, or persistent sleep problems, stop use and seek medical guidance.

Frequently Asked Questions

Related pages

• Brown Noise for Sleep — The free web player, plus the full guide to brown noise for sleep, focus, and tinnitus.
• OK-to-Wake Clock — A moon for stay in bed, a sun for time to get up. For toddlers.
• Baby Sleep Calculator — A bedtime for your baby or toddler, from the CDC sleep hours by age.
• Baby Sound Machine — White noise, shush, heartbeat and more, with a timer and night light, used the safe way.
• Decibel Meter — Check how loud your room is, and which noise colour covers it best.
• Brown Noise — The deepest colour: a steady rumble that is best for traffic noise and long nights.
• Brown Noise Generator — A real brown noise generator in your browser: made live as you listen, with no file and no loop.
• White Noise — The flat, bright colour, and the best of the five at making speech impossible to follow.
• Green Noise — The middle colour: pink noise with the middle sounds made stronger, and the only one of the five with no standard definition.
• Brown Noise for Tinnitus — Masking versus getting used to tinnitus, why the pitch of your tinnitus decides the colour, and where sound therapy really sits in the 2014 medical guideline.
• Brown Noise App — Which brown noise app to install, whether it is really free, and what an app can do that a browser tab cannot.
• Brown Noise Machine — Two very different products are sold as a brown noise machine, and one of them cannot make brown noise. What to check before buying.
• Sound Masking — Masking does not block sound. It raises the background so the noise stops standing out, and the colour has to match the noise.