It truly pains me to bring you tired parents another round of “Is this bad for my baby?” But this week, a new study suggests that some white noise machines designed for babies can produce harmful amounts of sound.

Before you despair about trashing your baby’s hearing, please keep in mind that like any study, the results are limited in what they can actually claim. And this one is no exception.

I learned the power of white noise when Baby V and I ventured out to meet some new mamas for lunch. As I frantically tried to reverse the ensuing meltdown, another mom came over with her phone. “Try this,” she said as she held up her phone and blasted white noise. Lo and behold, her black magic worked. Instantly, Baby V snapped to attention, stopped screaming and stared wide-eyed at the dark wizardry that is the White Noise Lite app.

Since then, I learned that when all else failed, the oscillating fan setting could occasionally jolt Baby V out of a screamfest. In general, I didn’t leave the noise on for long. It was annoying, and more importantly, it stopped working after the novelty wore off.

But lots of parents do rely on white noise to soothe their babies and help them sleep through the night. These machines are recommended on top parenting websites by top pediatricians, parenting bloggers and, most convincingly, all of the other parents you know. Use liberally, the Internet experts recommend. To reap the benefits, white noise machines should be played all night long for at least the entire first year, many people think. And don’t be shy: The noise should be louder than you think.

These machines are inescapable. But now, a study published online March 3 in Pediatrics is attempting to silence these ringing endorsements. After analyzing the max output of these machines, the study authors conclude that some have the potential to harm babies.  

Pediatric ear surgeon Blake Papsin at the Hospital for Sick Children in Toronto got interested in these white noise machines when he went into a patient’s room and was blasted with white noise. “The parents said, ‘Oh, the sleep doula tells us this is good for sleeping,’” Papsin recalls. The next time he went into the room, he brought a sound pressure meter. “Eighty-five decibels is what this thing was pumping out,” he says. That’s a level that can be reached by a loud hair dryer.

Curious about this modern-parenting phenomenon, Papsin and colleagues bought 14 commercial noise machines marketed for babies and tested their noise output when turned up all the way. “To our surprise, three of the devices were capable of presenting a toxic, hazardous level of sound,” he says. At a distance of 30 centimeters (to mimic crib-rail placement), those three machines were pumping out noise louder than 85 decibels, the limit set as safe for workplaces. Above that limit, government regulations mandate that adults wear ear protection.

Those three machines were the worst offenders, but all of the machines were capable of exceeding 50 decibels, the level considered safe for nurseries in hospitals. These levels were hit from a distance of 30 and 100 centimeters (mimics placement near the crib), the team found. All but one machine still pumped 50 decibels from a distance of 200 centimeters.

Because of this potential for harm, Papsin and colleagues recommend regulations that prevent these machines from producing more than 85 decibels and suggest the machines have automatic shutoffs. Papsin would also like to see a warning on the side that urges parents to use the machines for a short amount of time at the lowest volume possible.

Before you throw away your expensive noise machine and kiss sleep goodbye, consider the wisdom of a dissenting voice. Those recommendations are “desperately incorrect,” says pediatrician Harvey Karp of the University of Southern California. The authors of the new study “take a certain amount of information that’s correct and accurate, but they conclude the wrong thing,” says Karp, who advocates the use of white noise during sleep for babies in his popular book The Happiest Baby on the Block.

Of course babies shouldn’t have really loud noise blasted at their heads all night, Karp says, but there’s absolutely no evidence that more moderate sounds, around 65 to 70 decibels or the sound of a soft shower, are harmful.

What is harmful, Karp says, is taking away a safe and effective tool to help babies and their parents sleep. “I’m much more concerned about what I know are real and serious risks,” Karp says. Sleep-deprived parents are more tempted to do things like put the baby to sleep on his stomach or take the baby into bed with them — practices known to cause infant deaths.  

“To say these things can be misused, I think that’s a good and valuable addition that this report has contributed to the literature,” Karp says. “But their conclusions are totally unfounded, incorrect and contrary to the public health.” Parents shouldn’t be afraid to use moderate white noise during sleep, Karp says.

So what’s a parent to do? We don’t have good studies on the effects of moderate white noise on babies, but white noise does seem to help lots of babies and parents sleep better. Now, we have this new piece of information that says some of these machines might be dangerous at high blasts for a long time. But for now, I think it’s premature to tell parents to stop using this tool altogether.