These days, even 3-year-olds wear headphones, and as the holidays approach, retailers are well stocked with brands that claim to be “safe for young ears” or to deliver “100 percent safe listening.” The devices limit the volume at which sound can be played; parents rely on them to prevent children from blasting, say, Rihanna at hazardous levels that could lead to hearing loss.

But a new analysis by The Wirecutter, a product recommendations website owned by The New York Times Company, has found that half of 30 sets of children’s headphones tested did not restrict volume to the promised limit. The worst headphones produced sound so loud that it could be hazardous to ears in minutes.

“These are terribly important findings,” said Cory Portnuff, a pediatric audiologist at the University of Colorado Hospital who was not involved in the analysis. “Manufacturers are making claims that aren’t accurate.”

The new analysis should be a wake-up call to parents who thought volume-limiting technology offered adequate protection, said Dr. Blake Papsin, the chief otolaryngologist at the Hospital for Sick Children in Toronto.

“Headphone manufacturers aren’t interested in the health of your child’s ears,” he said. “They are interested in selling products, and some of them are not good for you.”

Half of 8- to 12-year-olds listen to music daily, and nearly two-thirds of teenagers do, according to a 2015 report with more than 2,600 participants. Safe listening is a function of both volume and duration: The louder a sound, the less time you should listen to it.

It’s not a linear relationship. Eighty decibels is twice as loud as 70 decibels, and 90 decibels is four times louder.

Exposure to 100 decibels, about the volume of noise caused by a power lawn mower, is safe for just 15 minutes; noise at 108 decibels, however, is safe for less than three minutes.

The workplace safety limit for adults, set by the National Institute for Occupational Safety and Health in 1998, is 85 decibels for no more than eight hours. But there is no mandatory standard that restricts the maximum sound output for listening devices or headphones sold in the United States.

When cranked all the way up, modern portable devices can produce sound levels from 97 to 107 decibels, a 2011 study found.

A team at The Wirecutter used two types of sound to test 30 sets of headphones and earbuds with an iPod Touch. First, they played a snippet of Major Lazer’s hit “Cold Water” as a real-world example of the kind of thumping music children listen to all the time.

Second, the testers played pink noise, usually used to test the output levels of equipment, to see whether the headphones actually limited volume to 85 decibels.

Playing 21 seconds of “Cold Water” at maximum volume, half of the 30 headphones exceeded 85 decibels. The loudest headphones went to 114 decibels.

With pink noise, roughly one-third exceeded 85 decibels; the loudest was recorded at 108 decibels. Complete results are available at thewirecutter.com.

To pinpoint the earbuds that did reduce volume, the Wirecutter team hooked up a computer to a simulated ear with a microphone inside and a coupler that models the acoustics of an ear canal.

Brian Fligor, an audiologist who is a member of the World Health Organization’s working group on safe listening devices, advised the team on how to compare its results to data on the 85-decibel workplace limit. (Headphones and earbuds are much closer to the ear, obviously; the workplace limit was devised with open areas in mind.)

Lauren Dragan, an editor at The Wirecutter, also corralled a half-dozen children, 3 to 11 years old, to try on each model, choose favorites and compile a “hate list” of ones they would never use.

In the end, the overall pick for the children was a Bluetooth model called the Puro BT2200 ($99.99). The headphones were well-liked by both toddlers and tweens, had excellent sound quality, offered some noise cancellation features and adequately restricted volume as long as the cord wasn’t used.