White noise, pink noise, and brown noise: how they sound different

What "color" means in noise

Noise color is a label for how a sound's power is distributed across frequencies. The general relationship is described by a formula where power spectral density is proportional to one over frequency raised to an exponent. When that exponent is zero, every frequency carries equal power and the noise is called white. As the exponent increases, low frequencies carry proportionally more power and high frequencies carry less.

The naming convention borrows loosely from light. White light contains all visible wavelengths in roughly equal measure, so white noise contains all audible frequencies at roughly equal power. Pink and brown shift the balance toward lower frequencies, each by a different amount.

White noise: flat across the spectrum

White noise has a flat power spectral density. Every frequency band from low bass to high treble receives the same amount of energy. In signal-processing terms, its spectral exponent is zero, so there is no rolloff at all.

Because every octave gets equal power, and higher octaves contain more individual frequencies, white noise sounds bright and hissy to most listeners. It is often compared to an untuned radio, a loud fan, or steady television static. The high-frequency content is what gives it that sharp, airy quality.

Some people find white noise effective at masking sudden sounds like traffic or conversation because it covers a wide frequency range evenly. Others find the treble tiring after a while, especially at moderate-to-high volumes.

Pink noise: equal energy per octave

Pink noise rolls off at about 3 decibels per octave. That means each time the frequency doubles, the power drops by half. The result is sometimes called one-over-f noise because power is inversely proportional to frequency.

This rolloff roughly matches the way the human ear perceives loudness across the spectrum. Many listeners describe pink noise as more balanced or natural than white noise. Common comparisons include steady rain on a roof, a distant waterfall heard from a distance, or wind moving through trees.

Pink noise is widely used in acoustics for room measurement and speaker calibration precisely because its per-octave energy distribution aligns with how we hear. That practical fact does not mean it is automatically better for sleep or concentration, but it helps explain why it often sounds less fatiguing than white noise at the same overall volume.

Brown noise: the deepest of the three

Brown noise, also called Brownian or red noise, rolls off at about 6 decibels per octave, twice the slope of pink noise. Its power spectral density is proportional to one over frequency squared. The name refers to Robert Brown and the random molecular motion he described, not to the color.

With most of its energy concentrated in the low end, brown noise sounds like a deep, steady rumble. Think of strong wind against a building or the low drone inside an airplane cabin. High frequencies are still present but very quiet relative to the bass.

Brown noise has gained popularity online, particularly among people who say it helps them focus or sleep. Our separate article on brown noise and what the research says covers the current evidence in detail. The short version: direct studies on brown noise specifically are scarce, and comfort is not the same as a proven clinical effect.

Side-by-side comparison

White noise has a spectral exponent of zero, no rolloff, and sounds bright and hissy. Pink noise has a spectral exponent of one, rolls off at about 3 decibels per octave, and sounds balanced, like steady rain. Brown noise has a spectral exponent of two, rolls off at about 6 decibels per octave, and sounds deep and rumbly.

All three are continuous, broadband, and unpitched. The difference is entirely in how energy is weighted across the frequency range. Moving from white to pink to brown is like slowly turning down the treble on a stereo while leaving the bass unchanged.

Which one sounds best is personal

There is no objectively correct noise color for relaxation, sleep, or focus. Preference depends on your hearing, your environment, and what you find comfortable. Someone who sleeps near a busy street might prefer a brighter noise that masks high-pitched sirens. Someone who already has a quiet room might prefer a low rumble that adds warmth without adding brightness.

A 2021 systematic review of broadband noise as a sleep aid found that existing studies were generally small and varied widely in method. The review concluded that evidence for noise improving sleep quality was not strong enough to make firm recommendations. That applies to all three colors discussed here.

If you want to compare them yourself, try listening to each at a comfortable, low volume for a few minutes. Soothescape includes synthesized white, pink, and brown noise as individual layers, and you can blend them or pair them with ambient sounds. Five hours of open listening lets you explore every combination before deciding.

Layering noise colors

Because each color emphasizes a different part of the spectrum, layering two together can create a blend you would not get from either alone. Mixing a quiet white layer with a louder brown layer, for example, keeps the low-end warmth but fills in some high-frequency detail. The result sits somewhere between the two.

In Soothescape, you can stack up to four layers and adjust each one's volume independently. This means you can build a custom spectrum that suits your preference instead of settling for one fixed color. Saved mixes let you return to a combination that works without rebuilding it each time.

Keep the volume comfortable

The National Institute on Deafness and Other Communication Disorders notes that sounds at or below 70 A-weighted decibels are unlikely to cause hearing loss even over long periods. Prolonged exposure at or above 85 decibels can cause damage. Background noise for sleep or focus should sit well below conversational volume, which is typically around 60 to 70 decibels.

Noise that feels soothing at a moderate level can still be too loud for an eight-hour stretch. A simple check: if you have to raise your voice to talk over it, it is too loud for extended use.

What noise will not do

Enjoying a particular noise color is not evidence that it treats insomnia, ADHD, anxiety, tinnitus, or any other condition. Some laboratory studies have explored timed sound pulses synchronized to brain activity during sleep, but those protocols are different from playing continuous noise through a phone speaker. Our article on pink noise and the research behind it discusses that distinction in more detail.

If a noise color helps you settle into a routine or block out distractions, that is a reasonable thing to use. Just keep expectations grounded in what the sound actually is: a steady, comfortable background, not a medical intervention.