White noise is a sound that contains many frequencies, with equal intensity at each frequency. It is called “white” noise because it is analogous to white light which contains all visible frequencies. Examples of white noise include the sound of a fan, the static sound of a radio tuned between stations, and the background hiss of a recording. Many people find white noise to be relaxing and sleep-promoting. However, some concern exists over potential harm from white noise, particularly in infants and young children. Here we review the evidence on whether white noise is truly harmful.
What is white noise?
White noise contains a blend of all audible frequencies with equal intensity per hertz. It is called “white” by analogy to white light which contains all visible wavelengths. In contrast, most sounds we hear in nature consist of only a few frequencies, or tones. For example, the clear sound of a trumpet consists primarily of its fundamental tone and overtone frequencies.
White noise draws its name from white light and follows a similar principle. White light contains all visible wavelengths, and white noise contains all audible frequencies. Just as white light appears featureless, white noise typically has no identifiable tones or patterns. Instead it is perceived as a consistent background hiss.
Technically speaking, true white noise would contain infinite frequencies at equal intensity. Most white noise used in practical applications is therefore not perfectly “white”, but is still referred to as white noise provided it contains a sufficiently broad, uniform blend of frequencies.
Examples of white noise
Here are some common examples of white noise:
- Air conditioner noise
- Fan sounds
- Radio static between stations
- Hissing or rumbling background noises
- Noise from household appliances
- Ocean surf sounds
Certain electronic devices can also generate white noise. Examples include white noise machines, white noise phone apps, and sound generators built into sleep-aid machines.
Why do people listen to white noise?
There are several reasons people commonly listen to white noise:
- Improve focus – The background noise masks distracting sounds, allowing better focus on work/tasks.
- Promote sleep – The non-jarring sound blocks disruptive noises that may disturb sleep.
- Relaxation – Some find the consistent sound to be soothing and relaxing.
- Tinnitus masking – White noise can help mask ringing in the ears from tinnitus.
- Privacy – Running white noise can prevent eavesdropping on conversations.
There is some scientific evidence supporting these uses. Studies show white noise can boost focus and certain types of memory in areas with many distractions. It also promotes REM sleep cycles.
For masking tinnitus symptoms, bandpass filtered white noise centered around the frequency of the tinnitus tone provides the best masking effect. Relaxation effects likely stem from acoustical influences on mood and altering our perception of environments.
Overall, many people find white noise to be a useful auditory backdrop in their daily environments. But is long-term exposure harmful in any way?
Is white noise bad for babies?
There is particular concern over white noise usage in infants and young children. Newborns and babies up to around 6 months rely heavily on detecting differences between speech sounds to acquire language. Some worry that exposure to white noise during critical language acquisition phases could therefore impair development.
Additionally, the developing ear in young infants is delicate and vulnerable to damage from noise exposure. Several animal studies found high level white noise caused structural changes in auditory processing neurons during early development. However, the noise in these animal studies was extremely loud, such as 110 dB, equivalent to a chainsaw. Such noise levels far exceed white noise levels used around human infants.
Nonetheless, some human studies have found association between white noise exposure and language development issues. A 2020 study followed infants from birth to age 3.5 years with periodic language assessments. Infants who were exposed to white noise for sleeping had 2-3 times higher risk of speech and language problems. However, further studies are still needed to confirm this effect.
The American Academy of Pediatrics acknowledges this uncertainty around high level white noise impacts on infants. They recommend:
- White noise under 50 dB has not been demonstrated to cause harm.
- Keep white noise levels as low as possible while still being soothing.
- Place noise machines as far from crib/bed as possible.
- Consider alternatives such as ambient noise CDs.
More research is still needed into the long-term impacts of white noise on infant development. Until more evidence is available, it seems prudent to be cautious and minimize excess exposure in infants when feasible.
Potential risks of white noise for babies
- Impaired language/speech development
- Impaired auditory processing
- Disrupted sleep from overstimulation
Volume recommendations
| Age | Maximum Recommended Volume |
|---|---|
| Infants (up to 1 year) | 50 dB |
| Toddlers (1-2 years) | 60 dB |
| Young Children (3-4 years) | 70 dB |
Is white noise bad for adults?
Less concern exists over white noise impacts on adults. However, some potential risks are still present with long-term nightly use.
A 2014 study surveyed over 13,000 adults on their white noise use for sleeping. They found no association between white noise use and cardiovascular conditions or depression. However, white noise users were more likely to have poor sleep quality and daytime sleepiness issues. The reasons for this are unclear but possible factors include noise interference with normal sleep architecture or insufficient masking of other noises.
Another study looked at effects of white noise on cognitive performance the following day. They found white noise exposure led to significantly worse performance on tasks involving processing speed, memory, and novel problem-solving. This indicates white noise at night could potentially impact work performance the next day.
From an auditory health perspective, white noise volumes in typical ranges for adults are not harmful. Problems would potentially arise only from misusing white noise machines at hazardously loud volumes for extended periods. Practical noise levels for adults remain below risk thresholds for noise-induced hearing damage.
While occasional use is likely fine, regularly using white noise on a nightly basis may disrupt normal sleep quality in some adults. Cognitive impacts the following day are also possible if white noise interferes with sleep. However, these effects likely depend on the individual person.
Potential white noise risks for adults
- Sleep disruption
- Daytime sleepiness
- Impaired cognitive performance
White noise alternatives
For those concerned over potential harms from white noise, some alternative options exist to consider:
- Pink noise – Lower intensity at higher frequencies than white noise. Perceived as more soothing.
- Brown noise – Deeper, rumbling effect. Mimics wind, thunder, or Deep ocean waves.
- Ambient nature sounds – Rain, ocean waves, crickets, etc. Provide natural background noise.
- Earplugs or sleep headphones – Physically block external sounds without noise emission.
- Sound insulation – Install soundproof materials to reduce noise penetration.
The most direct alternative to white noise is pink or brown noise. Their altered frequency balance provides a more relaxing, natural sound. If blocking external noises is the goal, then passive earplugs or active noise-cancelling headphones can physically attenuate distracting sounds without introducing additional noise.
Conclusion
Some potential for harm exists from overexposure to white noise, particularly in infants and young children. While occasional use is likely fine, regular nightly use can disrupt sleep quality or impact daytime cognitive performance in some adults. Lower sound levels are advisable for infants and limiting white noise use may be beneficial until more research clarifies its long-term impacts on language development.
However, used judiciously at reasonable volumes, white noise remains an effective acoustic therapy for many purposes. People sensitive to noise or prone to disrupted sleep often find white noise beneficial for relaxation, focus, or masking external distractions. Alternatives like pink/brown noise, nature sounds, or simple earplugs are also options that avoid any white noise risks.
In moderation, white noise can serve as a useful auditory backdrop for many environments. But prolonged exposure at high volumes or during critical developmental phases carries some potential for harm. Until more definitive research is available, a cautious approach seems sensible to balance white noise benefits against uncertainties of long-term impacts.