Finding the right sleep noise can mean better sleep for years to come. Learn the differences between white noise, pink noise, and Brown noise, plus how to pick a sound machine that will have you sawing logs all night long.

By Lauren Phillips
Updated August 22, 2019
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White Noise, Pink Noise, Brown Noise - definitions, machines, sounds, and more
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If you’ve suffered through a sleepless night (or several), you’ve likely tried a slew of sleep aids or remedies. One of those was probably white noise, either through a white noise machine, a white noise app, a white noise fan, or another sound machine. If it worked and your sleep dramatically improved, great—but if you didn’t like the white noise and stopped using it, you may not have tried the right sleep noise.

White noise gets a lot of attention, but there are other sleep noises out there that offer the same benefits. Namely, pink noise and Brown noise offer the same broad benefits for sleep, just with different sounds that are often more tolerable to people who don’t enjoy white noise. Picking a sleep noise comes down to preference, but understanding what the options are can help you be sure you’re picking the best—there’s so much more out there than white noise, if you’re willing to listen for it.

What is white noise?

White noise is a machine-generated sound that contains all frequencies.

“There’s been a lot of confusion about what white noise is,” says Sam Nicolino, a sound engineer, musician, and founder of Adaptive Sound Technologies (ASTI), which is behind the LectroFan and Sound+Sleep series of sound machines.

The phrase white noise has come to be broadly applied to all sorts of background noise, but white noise is actually a carefully constructed sound. It doesn’t occur in nature—it’s purely a mathematical construct, Nicolino says. Many sounds are similar to white noise, but they’re not quite the same.

The sound can be very staticky. “For most people, it’s very unpleasant,” Nicolino says—so if you tried a white noise machine and truly disliked it, you’re not alone or out of options.

The sleep benefits from white noise don’t come from the sound itself; they come from the sound’s ability to mask other disturbances.

“When you don’t have a sleep machine, every little noise that occurs in your sleep environment has the potential of rousing you,” says Rafael Pelayo, MD, a clinical professor in Stanford University’s Sleep Medicine Division, National Sleep Foundation board member, and long-time ASTI adviser. “Having a pleasing background sound can prevent you from hearing these little disruptive noises.”

Without disruptive noises, you sleep better. By increasing the level of background noise, a sound machine makes any sudden outside noises—think a barking dog, street traffic, or creaking pipes—less jarring, so people can learn to sleep through them, Dr. Pelayo says.

White noise is popular because it’s uniform, but what happens when you can’t stand white noise? It may be time to check out pink noise or Brown noise.

What is pink noise?

Pink noise is white noise with fewer high frequencies.

To create pink noise, Nicolino says sound engineers take white noise and filter out high frequencies. “Pink noise sounds kind of like rain,” he says. Like white noise, though, pink noise isn’t exactly like any noise from nature. Listening to a rainfall sound machine isn’t pink or white noise—it’s simply ambient sound recording on a loop.

What is Brown noise?

Sometimes called Brownian noise, Brown noise is white noise stripped of more high frequencies; it consists of lower frequencies than even pink noise.

“Brown noise can sound like a really uneventful ocean surf,” Nicolino says. It has more bass notes than white noise, making it more pleasant to listen to. And, unlike white and pink noise, Brown noise is named for Robert Brown, the discoverer of Brownian motion (which creates the sound), Dr. Pelayo says. (For the grammatically attentive, this is why Brown noise is often capitalized.) “People seem to prefer the lower-toned sounds,” Dr. Pelayo says.

How to pick a sleep noise or sound machine

Most sound machines—such as the sleep fan—emit only one sleep noise. This works if you like the noise, but it can limit options.

Some sound machines, such as the LectroFan from ASTI ($47;, offer many different sounds. In creating the sounds, Nicolino says, he and his team extended white, pink, and brown noise to create several different noises, ranging from white noise to a very deep Brown noise. This sound machine is, in effect, a white noise machine, a pink noise machine, and a Brown noise machine all in one, great for someone who can’t stand staticky white noise or who wants different sounds for different situations.

Beyond the noise itself, you should consider whether the sound machine or app you’re looking at loops. Some—especially those that feature nature recordings—loop the sound, which can disrupt sleep.

Other things to consider include volume control, sound quality, and the ability to both sense and hear deeper sounds, as you would with a deep bass. (If you do find lower tones more conducive to sleep, a sleep noise app may not work; only larger machines are able to create those two-sense sounds.) Many people use fans for ambient noise, but those can also make you cold. (This option allows users to block airflow if they like the sound of a sleep fan.)

At the end of the day (or night, in this case), it all comes down to personal preference. “People are going to choose a sound simply on what they like,” Dr. Pelayo says. “Once people settle into a sound spectrum that they like, they stick to it.”

Fans of nature sounds will gravitate toward those, rather than the more vague white, pink, or Brown noises. (This sound machine offers non-looping ocean, rain, and fireplace sounds.) Fans of whirring noises will stick with, appropriately, fans. And people who like white, pink, or Brown noise will find a machine that works for them and their needs.

The important thing, Dr. Pelayo says, is that you don’t force yourself (or your partner) to listen to the sound. (Don’t let a disagreement on the merits of white noise be the cause of your sleep divorce.) Focus on finding a noise that works for both of you, then give it a little time—most people adapt to a new sleep noise within two to three days, Dr. Pelayo says, though some may adapt immediately. (True insomniacs with a long history of irregular sleep may need much longer.) Once you’ve found your perfect sound machine and noise, you’ll likely want to stick with it for life.