Brown Noise for Babies
This page leads with the safety research rather than the sleep advice, because the published measurements on infant sound machines are unambiguous and most articles on this subject do not mention them at all.
What Researchers Measured Coming Out of Infant Sleep Machines
In 2014, a team in the otolaryngology — head and neck surgery department at the University of Toronto took fourteen infant sleep machines, set each one to maximum volume, and measured the sound pressure level coming out of them. 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, it is specific, and if you read one thing before putting a sound machine in a nursery it should be this.
They measured at three distances — 30, 100 and 200 cm — and applied correction factors to account for the acoustics of a six-month-old's ear canal, which is not the same as an adult's.
Every one of the fourteen machines exceeded 50 A-weighted decibels at 30 cm. All of them. That threshold is not arbitrary: 50 dBA is the recommended noise limit for infants in hospital nurseries, so the entire sample, at maximum volume and at cot-side distance, was above the level considered acceptable for an infant in a clinical setting.
Three of the machines produced more than 85 dBA. At that level, played for more than eight hours, the exposure exceeds the accumulated-noise limits set for adults in occupational settings — limits written for adult ears doing a day's work, not for an infant's developing auditory system overnight.
The authors' conclusion is measured and worth reading as written: these machines are capable of producing output sound pressure levels that may be damaging to infant hearing and auditory development, and the paper goes on to set out recommendations for safer operation. Note the framing carefully. The concern is not that the sound is white, brown or pink. The concern is level, distance and duration — the three things the study varied, and the three things you control.
The Three Dials That Matter, In Order
1. Distance does more work than the volume control. Sound level falls off with distance from the source, and in the open that fall is steep — roughly 6 dB for each doubling of distance, though a small enclosed room reflects sound and softens the reduction. Practically: moving a device from the cot rail to across the room is the single largest reduction available to you, it requires no judgement about levels, and it cannot be accidentally undone by a knock of the volume dial. Put the sound source as far from the cot as the room allows and still points towards the door or a wall rather than at the baby.
2. Level, set well below maximum and checked at the cot. The measurements above were taken at maximum volume, which is a setting no one should be using. Whatever level you choose, judge it standing where the baby's head will be, not from the doorway. A rough guide many clinicians use in conversation: the sound should be quieter than a normal speaking voice — if you have to raise yours to be heard over it at the cot, it is too loud. Free phone sound-level meter apps are not calibrated instruments, but they will reliably tell you the difference between roughly 50 dB and roughly 80 dB, and that is the distinction that actually matters here.
3. Duration, because exposure is level multiplied by time. The 85 dBA finding above was expressed as a limit over eight hours for a reason: the same level does more over a longer period. A device that runs from bedtime to morning delivers many times the exposure of one that fades out after the baby is asleep. A timer is not a convenience feature in this context; it is the third dial.
None of those three is specific 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 safety domain here that has nothing to do with hearing, and it takes precedence over 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 environment as including supine positioning, a firm and non-inclined sleep surface, room sharing without bed sharing, and the avoidance of soft bedding and overheating.
A phone, a cable, a plush sound machine, a speaker or a monitor clipped to the rail is not part of that picture. Whatever you use to make sound, it belongs on a surface away from the cot, with any cable routed where it cannot be reached — which happens to be the same placement the hearing evidence points to. The two safety considerations agree, which makes the rule easy: the sound source is across the room, and the cot contains the baby and nothing else.
If you are using a phone for this, put it face-down on a shelf on the far side of the room rather than anywhere within reach of the cot, and be aware that a phone is also a source of notification sounds and light unless you have deliberately silenced both.
There Is No Evidence Brown Noise Is Better for Infants
This site generates brown noise, and it would be straightforward to tell you it is the gentler, safer, more womb-like choice for a baby. There is no published basis for that, so this page will not say it.
What can be said is what is physically true. Brown noise puts most of its energy low in the spectrum, falling at close to 6 dB per octave, which means at a given overall level it carries much less high-frequency energy than white noise does. Whether that difference has any bearing on infant hearing or auditory development at the modest levels this page recommends has not been studied. The 2014 measurements found problems with level and distance across a whole sample of machines regardless of what sound they produced, which is a strong hint about where the risk actually sits.
There is also a practical argument that runs the other way, and it is worth knowing. Small speakers and phone speakers cannot reproduce low frequencies well, so brown noise played through them arrives thin and quiet — and the instinctive fix is to turn the volume up, which raises the level of everything the speaker can produce. That is a route to a louder nursery arrived at by accident. If a small speaker is what you have, a colour with more mid-frequency content will give you the same subjective effect at a lower setting.
Popular claims that a particular colour resembles the sound environment of the womb, or that a specific frequency is naturally soothing to newborns, are not supported by anything this page can cite. Treat them as marketing.
Does It Help Infants Sleep? The Evidence Is Weaker Than You Would Expect
Given how universal sound machines have become in nurseries, the state of the evidence is genuinely surprising.
The relevant systematic review is Riedy, Smith, Rocha and Basner, Noise as a sleep aid: A systematic review (Sleep Medicine Reviews, 2021), covering 38 articles on continuous noise as a sleep aid. Its conclusion runs against the popular understanding: the quality of the evidence that continuous noise improves sleep was judged very low, which the authors note contradicts its widespread use, and they raise the possibility that continuous noise may negatively affect sleep and hearing.
That review was not specifically about infants, and it did not isolate brown noise. But it is the best synthesis available on the underlying question, and it does not support the claim that a sound machine will improve a baby's sleep. Anyone who tells you it is proven to has not read it.
What is not in dispute is the acoustics. A steady broadband sound raises the threshold at which other sounds become detectable, so a door closing, a car outside or a sibling on the stairs is less likely to be perceived as a distinct event. If your specific problem is that your baby wakes when the house makes a noise, masking is a mechanism that plainly exists and brown noise is well suited to the low-frequency end of it. That is a much narrower claim than "helps babies sleep", and it is the only one this page will make.
Whether to use sound at all, and how, is a reasonable thing to raise at a routine appointment — particularly for a newborn, a premature baby, or an infant 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 seek advice if your baby has any ear discharge, appears to be in ear pain, or seems less responsive to sounds or voices than before. Do the same if a hearing screen was missed, failed or is outstanding.
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 escalating rather than easing. Masking sound covers noise; it does not address a cause, and a baby who cannot be comforted is a reason to speak to a clinician rather than to reach for a volume slider.
Be cautious about scaling up. If the level that used to settle your baby no longer does, the answer is not a higher setting — the safety findings above are all about level. That is the point to change something else, or to ask for help.
For a premature or low-birthweight infant, or any baby under specialist follow-up, ask before starting rather than after. Nursery noise limits exist because developing auditory systems are the specific case the limits were written for.
What a Timer and a Fixed Level Are Actually For
The player at the top of this page generates brown noise in the browser, continuously rather than from a recording, so there is no loop point and nothing that clicks or restarts. Free web sessions run for 30 minutes.
For a nursery, the features worth having are the boring ones, and they map directly onto the three dials above. A sleep timer caps duration, which is the dial most people ignore. Offline playback means no ads, no notifications and no dependence on the network to interrupt at two in the morning. Background playback means the sound does not stop because the screen locked. The free Android app does all three and removes the session limit.
Two things it deliberately does not do: claim to improve infant sleep, or recommend a level for you. It is a sound generator with a timer. The placement across the room, the level set at the cot and the decision to use it at all are yours, and 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
How loud is too loud for a sound machine in a baby's room?
The reference point from the research is 50 A-weighted decibels, the recommended noise limit for infants in hospital nurseries. In the 2014 Pediatrics study, all fourteen infant sleep machines tested exceeded that at 30 cm when set to maximum volume, and three exceeded 85 dBA — a level that over more than eight hours would exceed adult occupational exposure limits. So maximum volume is out, and the level should be judged at the cot rather than from the door. A practical check: if the sound is louder than a normal speaking voice at the baby's head, turn it down.
How far from the cot should the sound machine be?
As far as the room allows, and never on or attached to the cot itself. Distance is the most effective and most reliable control you have — level falls off steeply as you move away from a source, roughly 6 dB per doubling of distance in the open, less in a small reflective room but still substantially. The 2014 study measured at 30, 100 and 200 cm precisely because placement is a variable parents can change. Keeping the device off the sleep surface also lines up with the American Academy of Pediatrics' safe-sleep guidance, which describes a firm, non-inclined surface free of soft objects and loose bedding.
Can brown noise play all night for a baby?
It can, and there is a good argument for not letting it. Exposure is the product of level and time, so a device running from bedtime until morning delivers many times the dose of one that stops once the baby is asleep — and the eight-hour framing in the occupational limits referenced by the 2014 study exists for exactly that reason. A sleep timer is the straightforward answer: enough to get through settling and the first sleep cycle, then silence. If you do choose to run it overnight, that is a stronger reason to keep the level low and the distance large, and a reasonable thing to mention at your next appointment.
Is brown noise safer or gentler for a newborn than white noise?
There is no evidence for that, and this page will not imply it. No study has compared noise colours for infant hearing, infant sleep or auditory development. What is true is that brown noise carries less high-frequency energy at a given overall level, and what is also true is that it reproduces poorly on small speakers, which tempts people into turning the volume up — a real risk that works in the opposite direction. The 2014 measurements found level and placement problems across an entire sample of machines irrespective of the sound they made. Set-up is the safety variable; colour is not.
Will my baby become dependent on noise to fall asleep?
The honest answer is that we do not know — there is no good evidence either way, and anyone giving you a confident answer is not drawing it from research. It is a common enough parental worry that it is worth raising with your health visitor or paediatrician, who can speak to your child specifically. What can be said is that a timer means the sound is not present for most of the night, which sidesteps the question for a large part of it, and that infant sleep advice generally is a domain where a clinician who knows your family is worth more than a website.
Is it safe to use a phone next to the cot as a sound machine?
A phone is fine as a sound source and a poor choice as a cot-side object. Put it on a surface across the room, face down, with notifications silenced and the screen dark, and route any charging cable well away from the cot. A phone in or clipped to the cot introduces a loose object, a cable and a light source into the sleep space, which runs against safe-sleep guidance on keeping the sleep surface clear. Distance also gets you the level reduction you want for free, so the correct placement for hearing and the correct placement for safe sleep are the same placement.
Does a sound machine actually help babies sleep better?
Less clearly than its popularity suggests. The 2021 systematic review in Sleep Medicine Reviews covering continuous noise as a sleep aid rated the quality of the evidence that it improves sleep as very low, noted that this contradicts how widely it is used, and raised the possibility of negative effects on sleep and hearing. The narrower and better-supported claim is acoustic: steady broadband sound makes other sounds — a door, a car, a sibling — harder to detect as distinct events, which is a real mechanism if household noise is what wakes your baby. That is different from a general sleep benefit, and nobody has demonstrated the latter.