What Is White Noise?

White noise refers to a noise that contains all frequencies across the spectrum of audible sound in equal measure. Because white noise spans multiple bands of sound, it is sometimes referred to as broadband noise. Anecdotally, people often liken white noise to the static that comes from an untuned radio or television.

Researchers have studied the effect of white noise on humans for many years, finding evidence it can reduce crying in infants, improve work performance, and potentially help counteract symptoms of attention-deficit/hyperactivity disorder (ADHD). Multiple studies have also examined how white noise may affect human sleep.

White Noise vs. Other Colors of Noise

Although white noise is the most commonly known, there are several other colors of noise.

• Green Noise: While white noise contains equal volumes of all the sound frequencies, green noise amplifies the frequencies in the middle of that range. Green noise sounds are perceived as similar to ocean waves or a stream. Although there is limited research that shows green noise benefitting sleep, it is a popular tool to help mask noisy environments that disrupt sleep.
• Pink Noise: Like white noise, pink noise is a broadband sound containing components from across the sound spectrum. Pink noise contains sounds within each octave, but the power of its frequencies decreases by three decibels with each higher octave. As a result, pink noise sounds lower pitched than white noise. Researchers have compared the sound of pink noise to the noise produced by a waterfall. Studies have found that pink noise can enhance deep sleep in older adults and improve cognitive performance.
  Brown Noise: Brown noise, also called red noise, contains sounds from every octave of the sound spectrum, but the power behind frequencies decreases with each octave. This decrease is twice as great as that in pink noise, resulting in a sound people perceive as deeper than either white or pink noise. In research trials, people have said brown noise reminds them of the sound of rainfall or a shower. Studies have shown brown noise might be useful in reducing symptoms experienced by people who have ringing in their ears and at improving cognitive performance, but its effect on sleep has not been widely studied.
  

  Does White Noise Help You Sleep?

  More research is needed to confirm whether white noise improves sleep — perhaps by synchronizing brain waves — or if the sound primarily helps by masking background noise.

  A recent analysis of multiple studies looking at white noise’s effect on sleep has produced mixed results. The authors call into question the quality of existing evidence and conclude that further research is necessary in order to widely recommend white noise as a sleep aid. They also note that in some instances, white noise can disturb a person’s sleep and may affect their hearing.

  Studies have found that listening to white noise helped newborn babies fall asleep faster and affected the amount of time adults spent in different sleep stages when played throughout the night.
  Another study found that adults fell asleep 38% faster while listening to white noise. Other recent studies have continued to find white noise positively affecting sleep. For example, people living in a high-noise area of New York City fell asleep faster and spent more of their time in bed asleep while listening to white noise. In another study, listening to white noise through headphones improved sleep quality for critically ill patients in a loud hospital unit.
  
  Disruptive noise during sleep can cause changes in heart rate that suggest the sleeper is experiencing semi-awakenings. Transportation sounds like cars and planes are considered a major contributor to poor sleep, with possible health ramifications. Researchers are hopeful that the steady hum of white noise might reduce a sleeper’s sensitivity to unpredictable noises from the environment.
  

  How To Choose a White Noise Machine

  There are many factors to consider when choosing a white noise machine.

  • Machine or app: A white noise machine tends to be larger and more expensive, but it might come with better sound quality. A smartphone app could be more convenient while traveling, since it does not require you to bring any additional devices with you.
  • Cost: Some white noise apps offer a free or very low-cost version. White noise machine prices vary greatly, though many options cost between $50 and $100.
  • Sound quality: White noise machines either play a digital white noise recording or mechanically create a white noise sound. Check reviews of the white noise products you are considering to see what other customers have said about the sound quality.
  • Volume control: Being able to control the volume of your white noise machine is essential. Check the manufacturer’s specifications for the lowest and highest available volumes to ensure the white noise machine meets your needs.
  • Sleep timer: Most white noise machines have some type of sleep timer, but their functionality varies. Some allow the user to program in any amount of time, while others have preset blocks of time you can choose from.
  • Other sounds: If you have never used white noise to help you sleep before, consider opting for a white noise machine or app that also has other sleep sounds, in case you find you do not enjoy falling asleep to white noise. 

  Setting Your White Noise Machine Volume

  There are no official guidelines for setting the volume of a white noise machine for sleep. That said, exposure to noise measuring 70 decibels or more – like that of city traffic – can become hazardous over time. Ringing in the ears and hearing loss are both risks of regular exposure to loud sounds.One study found that nearly 65% of infant white noise machines and apps were capable of playing sounds louder than recommended when people slept very close to the device. When determining which volume setting to use for your white noise machine, consider first moving the white noise machine to a corner of the room and keeping the noise level similar to that of a background conversation or light rustling.