You’ve likely heard of white noise and know that it can help you tune out disturbing sounds so you can better work, relax or sleep. But white isn’t the only “color” of noise—there’s actually a whole spectrum of noise colors. However, the noise colors besides white that you’re most likely to hear about are pink noise…and brown noise. All three have different effects on your concentration and on sleep. Here’s what each kind of noise is and what each can do for you…


When you think of white noise, you probably think of a whirring fan, the sound of rain pattering on leaves, the hum of an air conditioner. But while your humming fan might help drown out your neighbor’s late-night patio party—at least somewhat—technically speaking, its sound isn’t white noise.

White noise is produced by combining all frequencies of sound within the range of human hearing in equal portions—technically that would include low or bass tones of about 20 hertz (Hz) up to high or treble tones of about 20,000 Hz. This creates a steady, featureless hissing sound similar to the static a TV or radio makes when it’s tuned between stations. It’s called white because just as white light combines all visible colors of the spectrum, white noise contains all frequencies—at least those that humans can hear.

Note: While white noise (and pink noise and brown noise) may be created with the full range of frequencies audible to humans, the spectrum of frequencies you’ll be able to hear depends on the fidelity of the sound system or device you’re listening on—and how good your hearing is. However, in practical terms, you still will be able to tell the differences between—and benefit from—the different colored noises.

What white noise does: By increasing the general level of sound that surrounds us, white noise makes it harder to notice individual noises—such as conversations or music on a nearby radio. Masking these distracting sounds improves our concentration and helps us relax.

In some places, such as a therapist’s waiting room, white noise preserves privacy by covering sounds from other rooms. White noise in the bedroom can help you sleep better by masking, for instance, street sounds or a television set in another room—or your sleeping partner’s snores! Even if you don’t need to drown out noise, the sound itself is soothing.


Pink noise is similar to white noise, but the power of the higher frequencies—the volume of the sound we hear—is decreased so that more bass (low) frequencies come through. This creates a sort of roar or rumble somewhat like the drum of a heavy rain storm on a roof or a large waterfall. Pink noise is perceived as less harsh and more balanced than the higher pitch of white noise. If the sound frequencies of pink noise were translated into light frequencies, they’d be at the red end of the light spectrum, but lightened because of the reduced power—hence, “pink.”

What pink noise does: If you find white noise relaxing and it seems to improve your sleep, you might be even happier with pink noise. A German study published in Neuron found that pink noise helped participants sleep more deeply. Bonus: They responded more accurately on a memory test the next morning!

Because pink noise is perceived as more soothing while still being just as good as white noise at masking unwanted sounds, pink-noise machines and apps have now outpaced the white-noise kind in popularity. Pink noise has become popular in office settings because it masks low-frequency background noise, potentially helping to increase concentration and productivity. In fact, when one company in Massachusetts moved to an open-floor office, they installed a pink-noise system that was specially designed to match the frequencies of the human voice. Pink noise has also been shown to be especially effective at soothing babies and small children.


Like pink noise, brown noise includes bass frequencies—but in greater proportion, giving it a deep, low humming quality that’s often compared to the crashing of large ocean waves or the drone of a strong, steady wind. This type of noise isn’t called “brown” because of any comparison with the color spectrum. Instead, it is named after Robert Brown, a 19th century botanist who discovered the random motion of microscopic particles that can be associated with this type of noise.

What brown noise does: Like white noise and pink noise, brown noise masks distracting sounds, improves concentration and can help you sleep better. In addition, the stronger low frequencies of brown noise are especially good for aiding deep relaxation, such as for meditation, and can improve reading comprehension.

Bottom line: As you can see, all three noise colors mask distracting or annoying sounds and can help you relax, including enough to sleep better. But while the different noise colors may be generally better for certain effects, it’s really a matter of what best helps you relax, sleep, concentrate, etc.

If you’d like to listen to examples of the different noise colors, here is…

You can learn more about color-noise machines in Bottom Line’s “The Best Sleep-Easy Machines.”