Healthy Sleeping Habits

The Difference Between White Noise, Pink Noise, and Brown Noise—And Which May Boost Your Memory While You Sleep

Photo: Stocksy/Leah Flores
The low hum of an air conditioner, the din of falling rain, the whoosh of a fan—you might consider any of these sounds, colloquially, to be white noise, or a consistent and continuous sound that could help you drift off to sleep. But, while any of these sounds could certainly offer that mind-numbing benefit, they’re not all necessarily classified as “white” noise, technically speaking. In fact, many of the most soothing tones fall into other sound-color categories of pink or brown noise, as opposed to white noise (and its typical radio-static hiss).

To be scientific, the difference between white, pink, and brown noise has to do with the power or intensity of sound waves across different frequencies. You can envision white noise as a sound where the intensity of all the different waves across the spectrum of audible sound is equal: one constant “shh” sound that gets its sleepiness-inducing power from its sheer evenness. Though pink and brown noise similarly contain all the waves of audible sound—also the reason why these colorful noises are collectively called “broadband” sound—the energetic power of their different frequencies diminishes with each higher octave, by three decibels for pink noise and six for brown.

The resulting amplification of lower tones in pink and brown noise could potentially make them even more calming to hear than white noise, which could come across as a bit shrill or harsh to some (more on that below). But, it’s worth noting that when it comes to sleep, the overall benefit of white, pink, or brown noise is always going to be a product of personal preference and environment, says Raj Dasgupta, MD, FAASM, sleep expert and spokesperson for the American Academy of Sleep Medicine. “For me, I do great with the washing machine running at night, whereas someone else might prefer a white-noise machine,” he says.

“Broadband sound reduces the difference in volume between the noise you’re hearing as you drift off and any jarring sound.” —Raj Dasgupta, MD, FAASM, sleep-medicine expert

One common denominator across these consistent sounds, though, is their ability to drown out any other noises that might otherwise interrupt sleep. “Broadband sound reduces the difference in volume between the noise you’re hearing as you drift off and any jarring sound, like the slamming of a door or a car driving by outside,” says Dr. Dasgupta. And by minimizing that potential change in sound, the background hum of white, pink, or brown noise could help prevent middle-of-the-night awakenings and, in turn, improve your sleep quality.

Below, sleep experts break down the differences between white, pink, and brown noise, and share their potential benefits for clocking sufficient good-quality sleep.

Here's the difference between white, pink, and brown noise

White noise

Generally, white noise sounds like the hiss of a radio tuned to an unused frequency. Just as white light contains all the light frequencies in the visible range, white noise contains all the sound frequencies in the audible range, creating what sleep doctors call a “sonic wall.” That essentially means that the sound is even and consistent, which can help block out external noise that might negatively impact sleep, says clinical psychologist and sleep physician Shelby Harris, PsyD.

Some research backs that up: A small 2017 study found that broadband sound administration reduced sleep onset latency (aka the time it takes to fall asleep) by 38 percent compared to normal environmental noise. And another small 2021 study showed that white noise improved sleep quality and duration in folks who lived in New York City and noted experiencing sleep disturbances due to high levels of environmental noise.

But, at the same time, a 2021 literature review of studies on white noise found that while it may, in some instances, reduce the amount of time it takes you to fall asleep, it doesn’t always have consistently positive effects on sleep quality and could even prevent the auditory system from fully winding down. So, essentially, if you’re not aiming to drown out jarring background noises, then a white-noise machine might not always be the sleep panacea that its reputation suggests.

Listen to it here.

Pink noise

With pink noise, you’re getting the hum of white noise but at a less shrill tone, as the intensity of its higher-frequency sound waves is lesser than that of the lower-frequency ones. Translation: Pink noise comes across more like the whoosh of consistent rainfall or a waterfall than it does radio static. “I describe pink noise as similar to white noise but with the base turned up,” says Dr. Dasgupta.

“Because certain elements of memory are dependent on spending time in this deeper, slow-wave sleep, it makes sense that pink noise could ostensibly help out with memory recall." —Dr. Dasgupta

In comparison, there are a few more studies on pink noise than there are on white noise to support its sleep-enhancing effects—namely, its ability to reduce brain-wave complexity (which can bring about more stable sleep) and even increase slow-wave brain activity during sleep. “Because certain elements of memory are dependent on spending time in this deeper, slow-wave sleep, it makes sense that pink noise could ostensibly help out with memory recall, too,” says Dr. Dasgupta. And that’s in line with the above study: Participants who were exposed to bursts of pink noise (when they were detected to have entered slow-wave sleep) performed three times better on a memory test the next morning than they did after a night of no noise.

Still, that study reflects a lab setting where the pink noise could be synced up with when each of the 13 participants drifted into deep sleep. And as a result, the link between pink noise and memory isn’t rock solid. “There’s not enough research that’s conclusive to say, ‘Listen to pink noise over white noise,’ but, that being said, if you have the option to try pink, you might as well try it out since there are a couple of these limited studies,” says Dr. Harris.

Listen to it here.

Brown noise

If pink noise is deeper in tone and intensity than white noise, then brown noise is even a bit deeper than pink. And by losing some of the volume of those mid- and high-range frequencies that are more strongly present in the other color noises, brown noise comes across more like the gentle rumble of the ocean, strong winds, or thunder than it does rainfall.

Although anecdotal evidence points to the benefit of brown noise for calm and sleep—and its deep tones may certainly create a more soothing, comfortable vibe than the sounds of its white and pink cousins—it hasn’t been rigorously studied, says Dr. Harris. “That’s why I tend to recommend anything that the person likes and is drawn to that’s a consistent noise—whether it be brown, pink, or white,” she says. “It's also the case that any of the above are likely to be more helpful for those people who have inconsistent noises in their sleep environments that they need to mask.”

Listen to it here.

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