The noise colors — white, pink, and brown — differ in exactly one way: how sound power is spread across the frequency range. White noise is flat: equal power in every equal-width band of frequency, so it sounds bright and hissy, like untuned-radio static. Pink noise tilts toward the lows — its power drops by about 3.01 dB per octave (proportional to 1/f), so it sounds softer and more natural, like steady rain. Brown noise (also called Brownian or red noise) tilts twice as hard, dropping about 6.02 dB per octave (proportional to 1/f²), making it the deepest — a low rumble, like distant thunder. Those figures are the technical definitions from Wikipedia's Colors of noise entry.
Which is "best" depends on what you're doing. For deep sleep, pink noise has the strongest evidence; for ADHD focus, white and pink noise show a small proven benefit; brown noise is the most popular online but the least studied. This guide defines each color precisely, then matches them to sleep, focus, ADHD, and tinnitus — with the honest state of the science for each, since the hype runs well ahead of the research.
The Noise Colors, Defined by Physics
The "color" names borrow from light: just as white light contains every visible wavelength at equal intensity, white noise contains every audible frequency at equal power. Tilt that flat spectrum toward lower frequencies and you get the warmer "colors."
The key idea is power spectral density — how much energy sits at each frequency. Engineers describe the tilt as a slope in decibels per octave (an octave = a doubling of frequency). Here's the core comparison:
| Noise color | Spectral slope (power) | What it sounds like | Often used for |
|---|---|---|---|
| White | Flat — equal power per Hz (0 dB/octave) | Bright, hissy "shhhh"; radio/TV static, a fan | Masking sudden sounds; falling asleep faster |
| Pink | −3.01 dB/octave — power ∝ 1/f | Softer, balanced, natural; steady rain, rustling leaves | Deep sleep; a less harsh background |
| Brown / red | −6.02 dB/octave — power ∝ 1/f² | Deep, bass-heavy rumble; distant thunder, a strong waterfall | Soothing racing thoughts; blocking low-frequency noise |
| Green (informal) | Mid-focused; extra energy near ~500 Hz | River, steady surf — "the background noise of the world" | Nature-leaning relaxation |
A note on why the tilt matters perceptually: human hearing works in proportional steps — going from 100 Hz to 200 Hz sounds like the same jump as 1,000 Hz to 2,000 Hz, even though one spans 100 Hz and the other 1,000 Hz. Because white noise puts equal power in every Hz, it crams far more energy into the high octaves than the low ones, which is why it sounds bright and even slightly harsh. Pink noise's −3 dB/octave roll-off exactly cancels that effect, distributing equal power per octave — which is why audio engineers use it as a reference signal and why most people find it gentler.
What about green noise?
Green noise is the one color you should treat with caution, because it isn't formally standardized. Wikipedia lists several competing definitions — the "mid-frequency component of white noise," a "vocal spectrum noise used for testing audio circuits," and "the background noise of the world" with more energy around 500 Hz — and the page explicitly warns that many noise colors are "used without precise definitions (or as synonyms for formally defined colors)." In practice, when people say green noise they mean a nature-flavored, mid-range sound — a river or steady surf — sitting between white and pink. It's a useful vibe, not a precise spec. You can play green noise free on HowWorks Sound, or the sleep version — no sign-up.
Which Noise Color Is Best for Sleep?
The honest headline: there's no single best. Northwestern Medicine puts it plainly — "the ideal one for you comes down to personal preference and life circumstances." But the three colors do lean toward different jobs.
White noise is the classic masker. By laying down a steady, full-spectrum sound barrier, it covers the abrupt noises — a door, a car, a snore — that jolt light sleepers awake, and it can shorten the time it takes to drift off.
Pink noise has the strongest research behind it. In a 2017 study published in Frontiers in Human Neuroscience, researchers played short pink-noise pulses to 13 adults aged 60–84, precisely timed to the upward swing of their slow brain waves during deep sleep. The result, per the study on PubMed Central: "Overnight improvement in word recall was significantly greater with acoustic stimulation compared to sham" — roughly a 26% improvement in word-pair recall — and that gain tracked with increased slow-wave activity. The important caveat is that this used lab equipment to phase-lock the sound to each person's brain waves; as the Sleep Foundation notes, "in order to obtain the full benefits of pink noise for sleep, it may be necessary for a lab technician to match pink noise timing to a person's brain waves." A plain pink-noise track on your phone isn't doing that — so treat the deep-sleep boost as promising rather than guaranteed at home.
Brown noise is the internet's darling and the lab's afterthought. Its deep, enveloping rumble is widely reported to quiet racing thoughts, but Cleveland Clinic is blunt that the benefits are "still under research, and that research is minimal." More broadly, a review of 38 studies on continuous noise and sleep found only limited evidence that it improved sleep — with some studies even showing it delayed or disrupted sleep. So if brown noise relaxes you, use it; just know the science hasn't caught up to the TikTok enthusiasm.
One rule cuts across all three colors — keep the volume modest. Cleveland Clinic suggests listening in brief sessions of 10 to 15 minutes and notes that prolonged listening at higher volumes can contribute to long-term hearing loss. A sleep timer is your friend.
Which Noise Color Is Best for Focus (and for ADHD)?
For focus, you have to split two very different questions: does noise help an ADHD brain concentrate? and does it help everyone else? The research gives surprisingly opposite answers.
For ADHD, the evidence is modest but real. A 2024 meta-analysis in the Journal of the American Academy of Child & Adolescent Psychiatry pooled 13 studies covering 335 participants and concluded: "White and pink noise provide a small benefit on laboratory attention tasks for individuals with ADHD or high ADHD symptoms, but not for non-ADHD individuals." The benefit was small but statistically significant (effect size g = 0.249). The leading explanation is the moderate brain arousal model — the idea that an ADHD brain is under-aroused, and a steady noise floor nudges its dopamine system up toward an optimal level via "stochastic resonance" (a real signal becoming easier to detect against a bit of added noise). Cleveland Clinic adds that brown noise may help people with ADHD by masking distracting thoughts — while cautioning there are "no significant studies to compare brown noise to white or pink noise for ADHD" specifically.
For people without ADHD, the same meta-analysis found the opposite — a small negative effect on attention tasks (g = −0.212). In other words, the noise that quiets an ADHD brain can mildly distract a neurotypical one. That fits a broader truth about background sound: its main reliable benefit for most people isn't a cognitive boost, it's masking. A constant, predictable sound floor hides the unpredictable interruptions — a coworker's call, a notification, a slamming door — that actually break concentration.
There's a related, well-established finding worth knowing if you're choosing between noise and music for studying: lyrics hurt. A study in the Journal of Cognition found "the presence of lyrics predicted decreased reading comprehension accuracy." Plain noise colors sidestep that entirely — there are no words to compete with the ones you're reading. If you'd rather have music than static, instrumental options like lo-fi work for the same reason; we cover the broader question in does music help you focus.
Which Noise Color Is Best for Tinnitus?
For tinnitus — the perception of ringing or buzzing with no external source — broadband noise is the standard self-help tool, used to mask the internal sound so it fades into the background. The American Tinnitus Association defines sound therapy as "the use of external noise in order to alter a patient's perception of, or reaction to, tinnitus," and notes that constant, noise-like sounds are effective for masking. Historically, white noise was among the first sounds used in tinnitus maskers.
Color choice is personal here. White noise covers the widest frequency range, which can be effective, but its bright high end is exactly what some tinnitus sufferers find grating — so many gravitate to the gentler low end of pink or brown noise, which still masks without the hiss. There's no one correct color; the goal is a comfortable sound that makes the ringing less noticeable.
One important boundary: tinnitus is a medical symptom with many possible causes (noise exposure, earwax, hearing loss, and more), so persistent or sudden tinnitus deserves a professional evaluation from an audiologist or physician. Sound therapy is a comfort-and-management tool, not a diagnosis or cure.
So, Is One Noise Color "Better"?
No — and now you can see why. The physics is settled (white is flat, pink rolls off −3 dB/octave, brown −6 dB/octave), but the benefits are use-case-specific and the evidence is uneven:
- Best-studied for deep sleep: pink noise.
- Modest proven benefit for ADHD focus: white and pink noise (and a mild downside for non-ADHD focus).
- Most popular, least proven: brown noise — soothing for many, but its benefits are "still under research."
- Most informal: green noise — a nature-leaning vibe with no fixed definition.
The deciding factor is almost always personal fit: the right color is the one that stops registering as a sound and just becomes the quiet you work or sleep inside. Brown if you crave a deep rumble; white if you mainly need to drown out chaos; pink if you want the middle path with the best sleep research. And whichever you pick, keep it at a gentle volume.
Hear the Difference Yourself
Descriptions of "−3 dB per octave" only get you so far — the colors are obvious the moment you A/B them. On HowWorks Sound you can play each one instantly in your browser, free and with no sign-up: white noise (bright and hissy), pink noise (softer, balanced), and brown noise (deep rumble). For overnight use, there are sleep-tuned versions — brown noise for sleeping, white noise for sleep, and pink noise for sleep — that you can leave running with a timer.
If you want to go deeper on the two most-asked-about colors, see what is brown noise and what is white noise. And if it turns out you'd rather focus to a beat than to static, do binaural beats work tackles another popular audio claim with the same evidence-first approach.
▶ Compare them yourself — play brown, white, and pink noise free on HowWorks Sound, no sign-up.