White vs Pink vs Brown vs Violet vs Grey Noise: The Full Guide

What does “noise colour” actually mean?

The analogy comes from light. White light contains all visible wavelengths in roughly equal measure. When you split it through a prism, you see the spectrum: red, orange, yellow, green, blue, violet. In audio, the equivalent is frequency, measured in Hertz (Hz). Humans hear from about 20 Hz (deep bass) to 20,000 Hz (very high pitch).

White noise contains equal energy at every frequency across the audible range. It follows the same logic as white light: every component is present at the same power level. The technical measurement is called power spectral density, and for white noise it is flat.

Other colours modify that flat spectrum by tilting it. Pink noise tilts the spectrum -3 dB per octave toward the bass end. Brown noise tilts it -6 dB per octave. Violet goes the other way, +6 dB per octave. These tilts change how the noise sounds and how it interacts with different hearing profiles and use cases.

White noise: the broadband masker

White noise has equal energy at every frequency. Because human hearing is logarithmic (we perceive octaves, not individual Hz), a flat power spectral density means each successive octave contains twice as many frequencies as the one below, and therefore sounds progressively brighter. This is why white noise has that characteristic high-frequency hiss quality, similar to TV static or a detuned radio.

White noise is the most effective broadband masker. Because it covers the entire frequency range evenly, it can mask sounds that fall anywhere in the spectrum. A door slamming, a conversation in the next room, traffic rumble, and high-pitched sirens are all attenuated more or less equally.

The downside is fatigue. Extended listening to pure white noise can feel harsh because the high frequencies that carry little perceptual information get the same energy as those in the most sensitive hearing range (roughly 1-4 kHz). Many users prefer pink or brown noise for long sleep sessions.

Pink noise: the sleep researcher’s favourite

Pink noise (-3 dB per octave, also called 1/f noise) is arguably the most studied noise colour in sleep research. Its spectrum slopes such that each octave contains equal total power, which matches human auditory perception more closely than white noise. This is why pink noise sounds more natural, like steady rain, a waterfall, or wind through leaves.

The most-cited study is Jiong and colleagues (2012, Frontiers in Human Neuroscience), which found that pink noise played in phase with slow-wave sleep (deep sleep) improved memory consolidation and the proportion of slow-wave sleep achieved. The study used 50 participants and found significant effects, though it used acoustic stimulation carefully timed to brain oscillations, not continuous background pink noise as typically used.

A 2017 study from Northwestern Medicine found similar slow-wave enhancement in older adults using timed pink noise pulses. The research is promising but based on stimulation protocols rather than simply running pink noise in the background. That distinction matters for honest recommendations.

For everyday sleep use, pink noise is the most popular choice. Its warm sound is less fatiguing than white noise, it masks most disruptive environmental sounds effectively, and the sleep-research literature gives it more credibility than any other noise colour for this application.

Brown noise: the deep rumble (and the TikTok phenomenon)

Brown noise (sometimes called Brownian noise or red noise, named after the mathematician Robert Brown who described Brownian motion) tilts the spectrum at -6 dB per octave. This is twice the slope of pink noise. The result is a sound dominated by bass and sub-bass frequencies: the rumble of distant thunder, the low roar of a powerful waterfall, strong wind against a building.

Brown noise became a major TikTok trend in 2022 and has continued into 2026. Users with ADHD reported that brown noise produced a quieting effect on internal mental chatter, describing it as “turning off the TV in my head.” The phenomenon is real in terms of reported experience, even if the clinical evidence for brown noise specifically is limited. See our ADHD guide for the research details.

For sleep, brown noise suits people who want a deeper, more immersive sound. Its low-frequency dominance provides strong masking of traffic and bass-heavy environmental noise. Some users find it too bass-heavy; the low-pass slider can warm up pink or white noise to approach brown if you want something between the two.

Violet noise: the tinnitus specialist

Violet noise (+6 dB per octave) is the spectral opposite of brown noise. Its energy concentrates in the upper end of the audible range. It sounds bright, somewhat like the high-frequency hiss you might associate with poor-quality audio recordings, CRT monitor interference, or certain industrial machinery.

The primary use case for violet noise is masking high-pitched tinnitus. If your tinnitus manifests as a high-pitched ring (typically above 4,000 Hz), violet noise offers more masking energy in that frequency range than any other colour. The approach is to set the generator’s high-pass filter to around your tinnitus frequency and use violet noise as the masker.

Violet noise is rarely used for general sleep or focus. The high-frequency content is fatiguing for most listeners. It is a precision tool, not a background ambiance. See our tinnitus masking guide for how to match noise colour to your tinnitus frequency.

Grey noise: perceptually flat

Grey noise is white noise shaped by an equal-loudness curve (sometimes called an A-weighting filter). The goal is a noise that sounds perceptually even across the entire audible range. Since human hearing is most sensitive around 1-5 kHz and less sensitive at low and very high frequencies, a flat spectrum (white noise) does not sound flat to the ear. Grey noise compensates for this.

The concept relates to work by Harry Fletcher and Wilden Munson (1933) and later to the ISO 226 equal-loudness contour standard. Grey noise aims to sit at a perceptually equal loudness across the hearing range, meaning no frequency region jumps out.

In practice, grey noise sits between white and pink in character. It is useful for users who find white noise too harsh but want a more neutral sound than the warmth of pink. It is also used in audio engineering for calibrating monitor systems and hearing assessments.

Where do rain and ocean sounds fit in the spectrum?

Natural rain sits close to pink noise in spectral character, with the individual impact transients from raindrops adding mid-frequency variation on top of a pink-ish baseline. Heavy rain shifts toward white noise because the impact energy at the water surface increases the high-frequency content. Light drizzle is closer to pink.

Ocean sounds have a rhythmic low-frequency component from wave cycles (0.1-0.5 Hz in terms of wave period, but audible content at 50-500 Hz) on top of a roughly pink background from water turbulence. Some researchers classify ocean ambience as “green noise” due to its mid-band emphasis, though green is not standardised the way white, pink, and brown are.

Frequency distribution diagram