What brown noise is

Like white and pink noise, brown noise contains the whole audible range at once. What sets it apart is the tilt. The Cleveland Clinic describes brown noise as a sound generated by random movement in which lower frequencies play louder and higher frequencies softer, producing a bass-heavy sound with a deep rumbling quality, and notes it has the highest emphasis on lower frequencies of the three common colors. The Sleep Foundation puts a number on the tilt: the decrease in power per octave is about twice as great as pink noise's. Its examples are the ones people recognize, waterfalls, thunder, crashing waves, showers, heavy rain and wind through trees, and in research trials listeners have compared it to rainfall or a shower.

Why people reach for it

The stated reason is usually masking. A steady, featureless sound raises the floor so that a door closing, a neighbor's television or your own train of thought is less likely to grab attention. The Cleveland Clinic lists what proponents claim on that basis: help with focus, with ADHD symptoms, with sleep, and with tinnitus. The appeal of the brown end specifically is that a low rumble is less fatiguing to sit inside for an hour than a bright hiss, which the same source characterizes as busy, frazzled and all over the place. That is a real difference in listening comfort, and comfort is a legitimate reason to prefer a sound. It is a different claim from a measured effect.

What the research actually supports

Very little, so far, and it is worth knowing that before you spend money on it. A 2021 systematic review in Sleep Medicine Reviews assessed 38 articles on continuous broadband noise and sleep and found research findings variable enough that the extremes were that continuous noise improves sleep and that it disrupts it. Against the GRADE criteria the quality of evidence for continuous noise improving sleep was very low, and the authors called for better studies before continuous noise is promoted as a sleep aid, noting it may also negatively affect sleep and hearing. On the focus and ADHD claims specifically, the Cleveland Clinic quotes a psychiatrist saying the research is minimal and there are no significant studies comparing brown noise to white or pink noise for ADHD.

Listening to it safely

Two numbers are worth carrying. The National Institute on Deafness and Other Communication Disorders states that sounds at or below 70 A-weighted decibels are unlikely to cause hearing loss even after long exposure, and that long or repeated exposure at or above 85 dBA can cause it, with louder sounds doing damage faster. The Cleveland Clinic is more cautious about habitual use: listen at lower volumes in brief periods of 10 to 15 minutes, and if the point is falling asleep, set a timer so your ears get a break rather than running the sound all night. Neither source suggests brown noise is dangerous at conversational volume. They suggest that all-night, headphones-on, volume-up listening is the pattern to avoid.

In short

  • Brown noise weights energy toward low frequencies, roughly twice as steeply as pink noise.
  • People use it to mask interruptions, and it is less fatiguing to sit inside than a bright hiss.
  • The Cleveland Clinic states there are no significant studies comparing brown noise to white or pink noise for ADHD.
  • A 2021 review of 38 studies rated the evidence for continuous noise improving sleep as very low quality.
  • Keep it at or below 70 dBA, and prefer a timer over running it all night.

Related guides

Sources