White Noise vs Pink Noise vs Brown Noise for Baby Sleep

Short answer: the color describes how bright or deep the sound is. White is hissy, pink is softer, and brown is a low rumble. Infant research mostly tested white noise, and there's no strong evidence that pink or brown works better for babies. Pick the one your baby settles to, and focus on volume and placement. Those matter far more for safety.

What the colors mean

Every steady noise is a mix of low, middle and high pitches. The color describes the balance.

Noise	How energy is spread	What it sounds like
White	Equal power at every frequency [1]	Bright and hissy, like TV static or a fan on high
Pink	Equal energy in every octave, so it falls about 3 dB per octave as pitch rises [1]	Softer and more balanced, like steady rain
Brown (also called Brownian or red)	Falls even faster with pitch: power follows 1/f² [1]	Deep and rumbly, like distant thunder or a strong waterfall

Why does white noise sound so hissy if every frequency gets equal power? Your ears hear pitch in octaves, and the higher octaves contain far more individual frequencies. So white noise packs most of its energy into the treble. Pink and brown shift that energy toward the bass.

What the research shows

White noise and newborns. In a small 1990 study, 40 newborns aged 2 to 7 days were split into two groups. In the white noise group, 16 of 20 (80%) fell asleep within five minutes, compared with 5 of 20 (25%) in the group without it. [2] It was a small, short study, but it's one of the most cited pieces of infant evidence.

Noise as a sleep aid overall. A 2021 systematic review of studies on continuous noise and sleep, mostly in adults, rated the evidence that continuous noise improves sleep as very low quality. The authors called for more research, noting noise may also negatively affect sleep and hearing. [3]

Pink noise headlines. You may have seen reports that pink noise boosts deep sleep and memory. In a 2017 Northwestern study of 13 adults aged 60 and older, a system delivered sounds timed precisely to each person's deep-sleep brain waves. Memory gains after those nights were about three times larger than after sham nights. [4] That's very different from a sound machine playing pink noise all night, and it wasn't studied in babies.

Brown noise. Brown noise is popular online, but we couldn't find published research on brown noise and infant sleep. Choose it because your baby likes it, not because of a claimed benefit.

What matters more than color

1. Volume at the crib. Keep it at about 50 dBA or lower where your baby's head rests. In a 2014 study, all 14 infant sleep machines tested at full volume exceeded that at about crib-rail distance. [5]
2. Distance. Place the machine across the room, never in or on the crib.
3. Steadiness. Constant sounds are easier to tune out than sounds that swell and fade, like waves, music or lullabies with silent gaps.
4. Duration. The 2014 researchers suggested shorter use and timers rather than all night. [5]

A note on measuring deep sounds

Sound meters usually report dBA, which weights sound the way human hearing does and counts deep bass less. [6] So a rumbly brown noise can read a lower dBA number than a bright white noise that seems equally loud. That's fine, since it reflects how loud it actually sounds. But don't push the bass up just because the number looks low. Keep it gentle.

How to choose

• Try each at a low volume across the room for a few nights.
• Notice what masks your home's noises. Deep brown noise covers rumbles like traffic or a dryer. Brighter white noise covers higher sounds like voices or clattering dishes.
• Keep what works, at the lowest effective level.

Frequently asked questions

Is pink noise better than white noise for babies? There isn't good evidence either way for infants. Pink is often gentler on the ears, so many parents prefer it.

Is brown noise safe for babies? Any steady noise can be used safely at a low volume, at a distance, and with a timer. The color doesn't change those rules.

What about womb sounds or heartbeat tracks? They're steady, low-pitched sounds, closer to brown or pink noise. The same volume and distance rules apply.

How the ARC is designed to help

The Selah ARC System, now in development, is designed to play steady, smooth noise and measure what actually reaches your baby. It adjusts to hold a 50 dBA hourly-average target, measured at the crib, whatever sound you choose. Follow the build.

This article is general information, not medical advice. Talk to your pediatrician about your child's sleep.

Sources

1. Wikipedia. Pink noise (definitions of white, pink and Brownian noise spectra).
2. Spencer JA, Moran DJ, Lee A, Talbert D. White noise and sleep induction. Archives of Disease in Childhood. 1990;65(1):135–137.
3. Riedy SM, Smith MG, Rocha S, Basner M. Noise as a sleep aid: a systematic review. Sleep Medicine Reviews. 2021;55:101385. doi:10.1016/j.smrv.2020.101385
4. Papalambros NA, et al. Acoustic enhancement of sleep slow oscillations and concomitant memory improvement in older adults. Frontiers in Human Neuroscience. 2017;11:109 (summary via ScienceDaily).
5. Hugh SC, et al. Infant sleep machines and hazardous sound pressure levels. Pediatrics. 2014;133(4):677–681.
6. Wikipedia. A-weighting.