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White Noise vs. Pink Noise vs. Brown Noise

They're often marketed as different products. Technically, they're the same idea — flat noise shaped by a filter — at three different slopes.

This is general information for a parenting/consumer audience, not medical advice. It doesn't replace guidance from your pediatrician, and every baby is different.

The actual definitions

"Color" of noise describes how loud each frequency is relative to the others — its spectral slope:

  • White noise has a flat spectrum: every frequency carries equal energy. It's the brightest and "hissiest" sounding of the three.
  • Pink noise falls off at about −3 dB per octave — equal energy per octave rather than per frequency, which happens to be closer to how human hearing perceives loudness across the spectrum. It sounds noticeably softer and warmer than white noise.
  • Brown noise (sometimes called red noise) falls off faster still, at about −6 dB per octave, emphasizing low frequencies heavily. It's the deepest and rumbliest of the three.

Rain, waves, fan, and vacuum sounds are, acoustically, mostly variations on these same broadband noise shapes filtered further.

What the research actually says about which is "better"

Most infant-sleep research has studied broadband/white noise specifically — that's what the founding 1990 sleep-onset study and most subsequent trials used. Pink noise is popular in commercial sleep products and general (adult) sleep-research marketing, partly because its energy distribution is closer to natural sounds like rain or wind and it's often described as gentler. We haven't found a controlled trial that isolates pink or brown noise specifically for infant sleep outcomes the way the white-noise studies do — so treat "pink noise is better for babies" as a plausible, popular claim rather than an established one.

Practical takeaway

All three are reasonable starting points, and which one soothes your particular baby is likely to come down to preference more than a proven physiological difference between the colors. The safety guidance — moderate volume, sensible distance, a timer — applies equally to all of them. See the loudness guide.

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