Glazik Prod SleepThunderstorm sounds for deep sleep3 hours · Black screen
What is the difference between white, pink, brown and green noise?
All four are made of every audible frequency at once. What changes is how loud the low sounds are compared with the high ones.
White noise gives every frequency the same energy. Our ears hear a lot of high pitch in it, so it sounds like a hiss: a detuned radio, a fan on full speed.
Pink noise gets 3 dB quieter every time the frequency doubles. The hiss softens and it sounds like steady rain or wind in the trees.
Brown noise (also called red or Brownian noise) drops twice as fast, 6 dB per octave. What remains is a deep rumble, like a waterfall heard from a distance or the inside of a plane.
Green noise has no scientific definition. The name is used online for noise centered on the middle frequencies, around 500 Hz, which some people compare to the background sound of nature. Our version is white noise filtered around 500 Hz.
Relative loudness by frequency (log scale). Lower line means quieter at that pitch.
| Color | Sounds like | Often used for |
|---|---|---|
| White | Hiss, fan, detuned radio | Masking voices and sudden noises |
| Pink | Steady rain, wind | Sleep, a softer alternative to white |
| Brown | Distant waterfall, plane cabin | Sleep, focus, covering low traffic rumble |
| Green | Soft mid-range, nature-like | Relaxation |
Which one is best for sleep?
The honest answer: nobody knows for sure. In 2021, a team of sleep researchers reviewed 38 studies on continuous noise and sleep. They rated the evidence that it improves sleep as very low. Some studies found people fell asleep faster, at least one found more disrupted sleep.
Pink noise gets the most attention because of lab studies where very short bursts of pink noise were played in sync with the sleeper's own deep sleep waves. Those waves got stronger and memory improved the next day. That setup measures the brain in real time. Playing pink noise all night from a speaker is a different thing, and it has not shown the same result.
Brown noise became popular on social media, but it has no dedicated sleep studies yet.
What does seem to work in practice is masking: a steady sound makes a door, a car or a neighbor less noticeable. So the best color is the one you stop noticing. If white feels harsh, try pink. If pink still feels sharp, try brown.
Brown noise for focus and ADHD
Many people with ADHD say brown noise helps them concentrate, and that experience is real for them. Science has not caught up: small studies on white noise and attention give mixed results, and there are no reliable studies on brown noise specifically. If it helps you work, use it, and keep the volume low.
How to use noise safely
Keep the volume as low as still works, around the level of a quiet conversation or lower, and put the speaker away from your head. Use the timer so the sound fades out once you are asleep.
For babies, be careful. A 2014 study in the journal Pediatrics measured 14 infant sleep machines: at 30 cm, all of them went above the 50 dB recommended for hospital nurseries, and three could exceed adult workplace limits at full volume. Use the lowest volume, keep the device far from the crib and turn it off after the baby falls asleep.
Curious about brain wave tones? Read do binaural beats work? and try our free binaural generator.
Prefer a longer soundscape?
Our channel publishes long sleep and meditation sessions with natural sounds and a black screen, so your phone stays dark.
Beach night soundsTheta waves · 1 hour
Questions
Which noise color is best for sleep?
No color has been proven best. Choose the one you notice least. Many people find brown or pink softer than white because they have less high-pitched hiss.
Does pink noise improve deep sleep?
Lab studies used very short bursts timed to brain waves. Continuous pink noise all night has not shown the same effect.
Is brown noise good for ADHD or focus?
Many people say yes, but there are no reliable studies on brown noise specifically. If it helps you, use it at a low volume.
Is it safe to sleep with noise all night?
Keep it quiet and away from your head, and use a timer. For babies, keep the device far from the crib at the lowest volume.
Is this noise generator free?
Yes. It runs in your browser, with no ads, no account and nothing to install.
Sources
Riedy SM et al. Noise as a sleep aid: a systematic review. Sleep Medicine Reviews, 2021. PubMed
Ngo HV et al. Auditory closed-loop stimulation of the sleep slow oscillation enhances memory. Neuron, 2013. DOI
Papalambros NA et al. Acoustic enhancement of sleep slow oscillations and concomitant memory improvement in older adults. Frontiers in Human Neuroscience, 2017. PubMed
Capezuti E et al. Systematic review: auditory stimulation and sleep. Journal of Clinical Sleep Medicine, 2022. PubMed
Hugh SC et al. Infant sleep machines and hazardous sound pressure levels. Pediatrics, 2014. DOI
This page is for general information and is not medical advice. If you have ongoing sleep problems, talk to a doctor.