July 16, 2024 – After a warm bottle of milk and a sweet lullaby, many babies drift off to sleep amid the hum of white noise. The broad spectrum of sound can muffle disruptions, help babies fall asleep, and make them sleep longer, achieving a kind of holy grail for the parents of newborns.
White noise machines are often included in the “must have” section of baby registries, and some parents continue to use them all night long throughout a child’s toddler years. Music streaming apps offer white noise playlists curated just for babies, and gadgets abound, including white noise players specifically designed for stroller naps. The feature is also built into many baby monitors.
But now, a group of medical researchers are calling for regulation of white noise devices for babies and young children after their new analysis concluded that long-term exposure to white noise at high volumes could harm development, with impacts ranging from hearing loss to learning setbacks. They warned that parents may be unknowingly exposing their young ones to the equivalent of a roaring subway train for a dozen hours per day or more.
Experts advise that until limits and warnings are put in place, parents and caregivers should measure and limit white noise volume, starting by downloading a sound level meter smartphone app.
“If used incorrectly, absolutely you can have permanent hearing loss from having a white noise machine blasting 24/7, or at the very least during the hours kids sleep, which is often 10 to 12 hours,” said Michelle Hu, AuD, a pediatric audiologist at San Diego State University Speech, Language, and Hearing Clinic, who wasn’t involved in the study. “One gunshot next to my ear would cause the same damage as listening to white noise or listening to music at a very loud level for 3 hours.”
What the New Study Found
The researchers did their analysis, published in this month’s edition of the journal Sleep Medicine, after one of the team members “had dinner with friends, and their child’s white noise machine was loud enough to hear in another room,” co-author Isaac Erbele, MD, a neurotologist with a specialty in surgeries of the ear and skull, said in an email.
Hearing damage due to noise exposure can add up throughout a person’s lifetime. That means parents should take precautions with noise, like the way they seek to avoid a child’s exposure to heavy metals, like lead, which can also cause increasing harm over a lifetime.
Erbele and his colleagues recommend that white noise used for children and babies be limited to 60 decibels. That’s the same volume as a normal conversation.
When sounds are too loud for too long, the tiny workings of the inner ear can be damaged beyond repair, and health risks are not limited to hearing loss. Children are at risk of other problems due to prolonged loud noise exposure, the researchers concluded.
“We found animal models that also suggest delayed development of language and auditory centers of the brain,” said Erbele. “The cause is unclear, and the animal model studies we included focused on development, rather than adult changes to the brain. Adult human studies have found decreased attention and increased mental workload with increased noise, and that [could] be what’s contributing to developmental delays.”
Commercially available white noise machines can reach a volume of 91 decibels, the researchers reported, which exceeds exposure recommendations for workers set by the National Institute for Occupational Safety and Health. White noise from a streaming playlist could very well be played at even higher volumes, depending on the capacity of speakers, such as playing the sounds through a cellphone, tablet, or standalone external speakers.
Of particular concern was the length of time that babies and young children may be exposed to white noise at high volumes, Erbele said. Some babies sleep up to 16 hours a day, and nighttime toddler sleep can span 12 hours.
For their analysis, the researchers combined the findings from 20 previous studies, including data about the effects of white noise on children, adults, and animals. They compared those findings to safety limits set by federal regulators to protect workers.
It’s common for medical researchers to take such a piecemeal approach, instead of designing a research study that could harm children by purposely exposing them to something that is suspected to be harmful. But the piecemeal approach does limit the study’s findings, which the team acknowledged by writing that “further research into the optimal intensity and duration of white noise exposure in children is needed.”
How to Use White Noise Safely
Erbele and other experts recommend that parents using white noise for their children be careful to limit volume, and fortunately, it’s not hard to do. Spreading the word, though, is key.
“More people need to know about it. More and more people are using white noise generators, and I did, too. When I had my first kid in 2018, I definitely played the white noise on the louder side,” said Hu, who also operates a website called Mama Hu Hears, which she describes as an online community with a mission of “helping hearing parents of deaf and hard-of-hearing children feel more confident on their journey.”
Hu said one day, she realized that she should check the volume of her white noise machine, recalling that there are standards for how loud noise exposure should be in the neonatal intensive care unit (NICU). Hu now limits her white noise machines to 45 decibels.
“As a desperate mom, you can be thinking, ‘It’s not working. I need to turn it up. They need it louder. It will calm them down if it’s louder.’ But that’s not the case,” she said.
The recommendations issued last year by the American Academy of Pediatrics suggest that white noise machines should be:
- Placed as far away from an infant as possible
- Used at the lowest setting possible
- Used for as short of a time as possible.
When the AAP recommendations on excessive noise exposure were published, lead author Sophie J. Balk, MD, said she was surprised by how many people focused on the paper’s small sections that discuss white noise. Balk, who is an attending physician at the Children's Hospital at Montefiore and a professor of pediatrics at the Albert Einstein College of Medicine in the Bronx, NY, fully expected the reaction to center on the widespread use of headphones, particularly given the rise of in-ear headphones such as AirPods.
Similarly, Hu said that the increasing use of white noise by parents and caregivers, plus research papers such as this latest one by Erbele and his colleagues, has prompted her to start asking about white noise use among her patients.
Hu and Erbele recommend downloading a smartphone sound level meter app to measure the volume of a white noise machine, such as the one developed by the National Institute for Occupational Safety and Health. The CDC says the app has been downloaded more than 2.5 million times. Measure the white noise volume where the child’s head is, and adjust the volume by moving the speaker farther away or turning the volume down.
Adults who use white noise while they sleep may also want to check the volume.
“If anything, the recommendation to turn down noise machines is stronger in adults,” said Erbele, who practices at Brooke Army Medical Center in San Antonio, TX, where he is the associate program director for otolaryngology – head and neck surgery. He is also an associate professor in the Department of Surgery at Uniformed Services University of the Health Sciences.
“The association between noise and hearing loss in adults is far better established,” he said. “The biggest difference is that most adults can turn down the sound if it’s bothering them. And the risk to adults is more related to permanent hearing loss than brain development.”
Research has linked noise to a range of health problems, from issues with the heart and blood vessels to dementia. It’s not uncommon for people to consider noise simply an annoyance, but it’s a public health matter, said Balk, a pediatric environmental health expert and associate editor of “Pediatric Environmental Health,” which is the AAP's handbook for health care professionals that is sometimes called “The Green Book.”
“In general, we just want to avoid loud volumes for long periods of time,” she said. “Hearing is lifelong, and you want to protect everything that is lifelong. You want to protect your heart and your lungs, you want to protect your skin. … It’s important to put hearing health on our agenda, starting in infancy.”
