Usually when you want good sleep, you want to avoid noise. But in the same way two negatives make a positive, there are types of noise that can make for better sleep by helping block out those problematic sounds — cars outside, noisy neighbors, a bedmate’s snoring — that keeping us from chasing those forty winks.
“Our brains are fine-tuned to pay attention to sudden changes in our environment,” says Chelsie Rohrscheib, Ph.D., sleep specialist and neuroscientist. “When a new sound occurs, such as a car horn or dog barking, our brains will automatically switch our attention from whatever task we were focusing on to the new, distracting sound.”
The sounds that might help turn down the volume on those distracting sounds are white, pink, and brown noise. These can muffle or eliminate those attention-grabbers and aid our brains in tuning out and drifting off.
Who Can Benefit From Having a Sound Machine?
Though white noise can help anyone who suffers noise-related sleeping issues, many white noise machines are marketed to new parents. White noise machines can soothe newborns, who are prone to overstimulation. The soothing sounds can mimic the gentle “wooshing” that babies heard in the womb, giving them a sense of familiarity.
Parents, however, should be cautious to use the lowest volume setting for little ears. Research shows that sound machines, even those designed or labeled for infants, are capable of producing sound pressure levels that could be damaging or hinder hearing development.
If you are using a sound machine to mask noise for your baby or child, researchers recommend placing the machine as far away from your child as possible, even across the room, and using the lowest volume setting. Also try to limit use, by turning the machine off after your child nods off, either manually or by using a smart plug that is controlled by an app on your phone.
How Do White, Pink, and Brown Noise Work for Sleep?
A sound machine might be a boon for anyone’s sleep. Even if you are getting your shuteye in the most silent of environments, the racing thoughts inside your mind — like to-do lists, worries, plans for the next day — can keep you from slumber. Sound machines with white, pink, or brown noise will help with those distractions, too.
“While we’re trying to sleep,” Rohrscheib says, “white, pink, and brown noise not only mask outside noise pollution but also help us ignore our own stressful thoughts that might keep us awake.”
| White | Pink | Brown | |
| Frequency | All audible frequencies played at equal energy/volume | Energy is concentrated at mid to lower frequencies | Energy is concentrated at lower frequencies |
| Sounds like | Radio static | Rushing water | Rumbling thunder |
| Research says | May help sleep and concentration | May help sleep and concentration | May help sleep and memory |
“Sounds exist at different frequencies,” Rohrscheib explains, “and some of these frequencies have been shown by science to help humans relax or concentrate in over-stimulating environments.”
Like light, sound is classified into different colors based on their frequency signature. And just like we do with colors preferences, we might have varying sound preferences. “Some people consider white noise to sound too high pitch, and prefer brown or pink noise instead,” Rohrscheib says.
So, What Is White Noise?
“White noise sounds similar to radio static and is the sound equivalent of white light,” Rohrscheib says. (White light contains all the colors of the rainbow, or the visible spectrum.)
White noise is the combination of every frequency the human ear can hear, played at the same volume. The human ear can hear frequencies from 20 to 20,000 Hz, although we lose some frequencies at either end of the spectrum as we age. And people with hearing loss won’t have access to the full range.
At the lower end of the spectrum, sounds might be rumbly, like the roll of thunder (not the crack), which is about 40 to 50 Hz. On the higher end of the spectrum, sounds might be screechy or whiny. Think of a mosquito, which is about 17,400 Hz.
Small experimental studies show that white noise can aid sleep by masking environmental noises. But a recent systematic review of research on white noise indicates there is not enough evidence to conclude whether white noise improves sleep. So ultimately, your mileage may vary.
White Noise May Benefit Concentration
Even if your sound machine — or audio apps that produce these steady streams of noise — doesn’t improve your sleep, it may help in other ways. For any task that requires focus, like studying for an exam, finishing up a grueling work report, or just reading a book, these sounds may help boost concentration.
One 2017 study looked at 80 participants. Half used white noise while memorizing a group of objects given word names they’d never heard of before. The other half completed their study session in silence. The researchers found that those who used white noise had better word recall accuracy on a memory exam than those who didn’t use noise while studying.
Is Pink Noise Better for Sleep than White Noise?
For sleep, pink noise may be a better choice than white. A small older study found that a steady dose of pink noise reduces brain wave complexity, boosting sleep stability, which could improve sleep quality. A more recent study found that pink noise aids deepen sleep and may have positive effects on memory.
This may be because pink noise sounds more soothing or pleasing to the ear than white noise. “White noise sounds like radio static,” explains Martin Reed, a certified clinical sleep health educator and the founder of Insomnia Coach, “pink noise sounds more like rushing water. So pink noise is thought to sound more natural than white noise.”
Like white noise, pink noise contains all the frequencies audible to the human ear. But instead of those frequencies all having equal intensity, pink noise has less intensity at the higher end of the spectrum.
According to Rohrscheib, pink noise emphasizes lower frequencies, you’re less likely to hear a high pitch.
How Does Brown Noise Compete with Pink and White?
Brown noise, also called Brownian and red noise, is said to feel “warmer” than white or pink noise. “Brown noise goes even lower in frequency than pink noise,” adds Rohrscheib. Examples of brown noise in nature include blowing wind, roaring river current, or rumbling thunder.
With brown noise, all the energy is concentrated at the lower frequency range. The filtering process produces an even “warmer” tone than the harsher high pitches of white noise or the more natural sounds of pink noise.
Research is scant on how brown noise affects sleep. But Rohrscheib says the lower frequencies of brown noise may make it the most relaxing of the three colors. That said, some may find that brown noise is a bit “rougher” than pink or white because of those deeply low frequencies.
How to Select a Sound Machine
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White, pink, and brown noise all have similar sounds rooted in nature, but choosing between these noises is not the same as playing the sound of a river or thunderstorm. In fact, you may want to opt for a sound machine rather than an audio track.
“Sound machines should emit sound as a constant volume and ideally have little audio variation,” Reed explains. “For this reason, nature sounds are not always helpful.”
Consider these features in a sound machine:
- Does it have various volume settings?
- Is it portable for travel, if that’s a requirement for you?
- Does it have a timer/automatic shutoff, if that’s a preference?
- Does it play continuous noise, rather than recordings that pause and play?
How to Choose a Noise
Ultimately, the sound color that works best for you will come down to a mix of personal preference, your environment, and even the task at hand.
Consider:
- White noise, if you have to sleep or work in a noisy atmosphere and want to boost your concentration.
- Pink noise, for deep sleep and if white noise feels too high-pitched
- Brown noise, if pink and white noise don’t bring relaxation
When it comes to choosing noise to block out all the other distracting sound, keep in mind that white noise will have higher pitches, brown noise will have lower frequencies, and pink noise might offer that Goldilocks-style just-right in between.
Prefer guided audio? There are plenty of options, from adult bedtime stories, scientifically-backed sleep songs, and sleep hypnosis tracks to keep your mind from wandering away from dreamland. And pro-tip: make sure your listening device has a sleep timer.
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