The Colors of Noise, Explained
White, pink and brown noise get recommended for everything from sleep to studying, but the names rarely come with an explanation. This guide covers what each color actually is, what it sounds like, and which one to reach for.
You can hear every color as you read: open the white noise generator in another tab and tap through them. The spectrum line in the player shows each shape as you go.
Noise, frequency and why colors
Noise, in the technical sense, is a random signal: no tune, no rhythm, just constant variation. What distinguishes one kind from another is how its power is spread across frequencies, from deep bass at 20 Hz to the highest treble around 20,000 Hz. That spread is called the spectrum.
The color names borrow from light. White light contains all visible frequencies equally, so noise with equal power at every frequency is white. Light weighted toward low frequencies looks red, so noise weighted toward the bass is pink or red (brown). Noise weighted toward high frequencies is blue or violet.
One more idea makes the colors make sense: we hear pitch in octaves. Each octave is a doubling of frequency, and each octave up contains twice as many hertz as the one below. So “equal power per hertz” and “equal power per octave” are very different things, and that difference is exactly the gap between white and pink noise.
The colors at a glance
| Color | Power per octave | Sounds like |
|---|---|---|
| Brown (red) | Falls 3 dB per octave (-6 dB per hertz doubling) | Waterfall, airplane cabin, distant thunder |
| Pink | Equal in every octave | Steady rain, wind in leaves |
| White | Rises 3 dB per octave | Radio static, a hissing vent |
| Blue | Rises 6 dB per octave | Hissing spray, a kettle |
| Violet | Rises 9 dB per octave | Very thin, high hiss |
| Grey | Shaped to sound equally loud | Even, slightly scooped |
| Green | Concentrated around 500 Hz | Forest ambience, distant surf |
You will often see the colors described per hertz instead: white is flat, pink falls 3 dB each time frequency doubles, brown falls 6 dB, blue rises 3 dB, violet rises 6 dB. The two descriptions are the same thing measured differently.
White noise
White noise has the same power at every frequency. Because the upper octaves contain so many more frequencies, it sounds bright and hissy. It is the classic masker: its strong treble covers speech and sharp sounds well, which is why it is used in sleep machines and for babies. Engineers use it to test equipment, and it appears naturally as the thermal hiss in electronics. Try white noise.
Pink noise
Pink noise has equal power in every octave. It sounds balanced to the ear, like steady rain, and is used to tune sound systems because it matches the way we hear. A surprising number of natural processes have a roughly pink spectrum, from heartbeat variability to river flows. In sleep science, short bursts of pink noise timed to deep-sleep brain waves have been shown to enhance those waves. Try pink noise.
Brown noise
Brown noise falls even faster toward the treble, leaving a deep rumble. It is named after Robert Brown and Brownian motion, not the color, and is made by a random walk: each value is the last one plus a small random step. It is the most comfortable color for many people, popular for sleep and for focus, especially among people with ADHD. Try brown noise.
Blue and violet noise
Blue noise rises toward the treble; violet rises faster still. Both sound sharp and thin. As listening sounds they are mainly used to mask high-pitched noises and some types of tinnitus at a low volume. Blue noise is important in image processing, where it spreads dots evenly without clumps, and violet noise is made by differentiating white noise. Blue noise, violet noise.
Grey and green noise
Grey noise is defined by perception rather than mathematics: white noise reshaped by an equal-loudness curve so every pitch sounds equally loud. It is gentle and even, a favorite for tinnitus. Try grey noise.
Green noise has no formal definition. It is generally used for noise concentrated in the middle of the spectrum, around 500 Hz, and it became popular as a sleep sound that resembles nature. Try green noise.
Black noise and other names
- Black noise usually means silence, or near-silence with occasional random spikes. It is sometimes used jokingly, and sometimes for active noise cancellation.
- Red noise is simply another name for brown noise.
- Orange, yellow and other colors appear occasionally but have no settled meaning.
Which color should you use?
| Goal | Start with |
|---|---|
| Sleep in a noisy home | Pink or brown |
| Cover voices and TV | White or pink |
| Cover traffic and bass | Brown |
| Focus and studying | Brown or pink; white for chatty spaces |
| Settle a baby | White, quietly, far from the crib |
| Tinnitus comfort | Grey, or a natural sound |
Frequently asked questions
What is the difference between white, pink and brown noise?
White noise has equal power at every frequency and sounds hissy. Pink noise has equal power in every octave and sounds balanced, like rain. Brown noise falls off faster toward the treble and sounds like a deep rumble.
Which noise color is best for sleep?
Pink and brown are the most popular because they are soft. White noise masks high sounds better. The best one is the one you stop noticing at a low volume.
Is brown noise named after the color brown?
No. It is named after Robert Brown, the botanist who described Brownian motion, the random movement that produces this kind of noise.
What is black noise?
Usually silence, or silence broken by rare random sounds. It is not used as a sleep sound in the way the other colors are.