What Is Pink Noise?

Pink noise has equal energy in every octave, so it sounds even to our ears: like steady rain. Here’s the science, the sleep research, and how it compares with white and brown noise.

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The short answer

Pink noise1 is random sound whose power falls as frequency rises, by 3 decibels per octave. Since each octave up is twice as wide in hertz, the power in every octave ends up the same. Our hearing works in octaves, so pink noise sounds evenly balanced from low to high. It’s often called 1/f noise, because its power is inversely proportional to frequency.

NoisePower per hertzPower per octaveSounds like
WhiteFlat+3 dB each octave upTV static, air from a vent
Pink−3 dB per octave (1/f)Equal in every octaveSteady rain, wind in trees
Brown−6 dB per octave (1/f²)−3 dB each octave upDistant waterfall, heavy surf
Blue+3 dB per octave+6 dB each octave upA fine, high hiss
Violet+6 dB per octave+9 dB each octave upA sharp, airy hiss

Pink noise in nature

The 1/f pattern turns up in surprising places: steady rainfall, wind, the flow of rivers, the fluctuation of heartbeats, even the loudness changes in a lot of music. That may be part of why pink noise sounds natural and calm, rather than mechanical.

What the sleep studies found

Pink noise became famous through research on deep sleep. In a 2013 study by Hong-Viet Ngo and colleagues2, short pulses of pink noise timed to the brain’s slow waves during deep sleep made those waves stronger, and participants remembered word pairs better the next day. Later work, including a 2017 study in older adults3, found similar effects.

Two important details: these studies used brief bursts timed precisely to brain waves measured with EEG, not a steady background; and the groups were small. A steady pink noise track at home is a pleasant masking sound, but it isn’t the same as the lab method. Be wary of anyone promising better memory from a pink noise playlist.

Steady pink noise all night: a caution

The newest evidence points the other way for a steady track. In a 2026 study from the University of Pennsylvania, 25 healthy adults slept seven nights in a sleep lab. Pink noise at 50 decibels all night was linked to almost 19 fewer minutes of REM sleep, people rated their sleep as lighter, and earplugs protected sleep from aircraft noise better than pink noise did 4. It fits a 2021 systematic review that rated the evidence for continuous noise as a sleep aid as very low quality 5.

None of this makes pink noise harmful at a low level for a short time. It does mean: keep it quiet, use a timer if you only need help falling asleep, and don’t assume more noise means better sleep.

Other uses

  • Focus: a softer alternative to white noise for long sessions. See focus sounds.
  • Sleep: many people prefer it to white noise because it’s less harsh. See sleep sounds.
  • Audio: engineers use pink noise to tune speakers and rooms, because it tests every octave equally.
  • Tinnitus: often used in sound therapy because it’s comfortable to listen to.

Hear it

Sources

  1. Wikipedia. Pink noise. en.wikipedia.org.
  2. Ngo HV, Martinetz T, Born J, Mölle M (2013). Auditory closed-loop stimulation of the sleep slow oscillation enhances memory. Neuron 78(3):545–553.
  3. Papalambros NA, Santostasi G, Malkani RG, et al. (2017). Acoustic enhancement of sleep slow oscillations and concomitant memory improvement in older adults. Frontiers in Human Neuroscience 11:109.
  4. Basner M, et al. (2026). Efficacy of pink noise and earplugs for mitigating the effects of intermittent environmental noise exposure on sleep. Sleep.
  5. Riedy SM, Smith MG, Rocha S, Basner M (2021). Noise as a sleep aid: a systematic review. Sleep Medicine Reviews 55:101385.

Questions

Is pink noise better than white noise?

It’s softer and more balanced to the ear, so many people prefer it for long listening. White noise is a stronger mask for voices.

Does pink noise improve memory?

Lab studies with pink noise pulses timed to deep-sleep brain waves found small memory improvements. A steady pink noise track at home hasn’t been shown to do the same, and a 2026 study found all-night pink noise at 50 dB reduced REM sleep.

What does pink noise sound like?

Like steady rain or a waterfall: a soft, even rush.

Last updated .