WASHINGTON — From the cacophony of day care to the buzz of TV and electronic toys, noise is more distracting to a child’s brain than an adult’s, and new research shows it can hinder how youngsters learn.

In fact, one of the worst offenders when a tot’s trying to listen is other voices babbling in the background, researchers said Saturday at a meeting of the American Association for the Advancement of Science.

“What a child hears in a noisy environment is not what an adult hears,” said Dr. Lori Leibold of Boys Town National Research Hospital in Omaha, Neb.

That’s a Catch-22 in our increasingly noisy lives because “young children learn language from hearing it,” said Dr. Rochelle Newman of the University of Maryland. “They have a greater need for understanding speech around them but at the same time they’re less equipped to deal with it.”

It’s not their ability to hear. For healthy children, the auditory system is pretty well developed by a few months of age.

Consider how hard it is to carry on a conversation in a noisy restaurant. Researchers simulated that background in a series of experiments by playing recordings of people reading and talking while testing how easily children detected words they knew, such as “playground,” when a new voice broke through the hubbub, or how easily they learned new words.

It’s not just a concern for toddlers and preschoolers. The ability to understand and process speech against competing background noise doesn’t mature until adolescence, Leibold said.

Nor is the challenge just to tune out the background buzz. Brief sudden noises — someone coughs, a car horn blares — can drown out part of a word or sentence. An adult’s experienced brain automatically substitutes a logical choice, often well enough that the person doesn’t notice, Newman said.

“Young children don’t do this. Their brain doesn’t fill in the gaps,” she said.

Children who were born prematurely may have an additional risk. When preemies spend a long time in an incubator, their brains get used to the constant “white noise” of the machine’s fan — different from a full-term baby who develops hearing mom’s voice in the womb and thus is wired to pay more attention to voices, said

Dr. Amir Lahav of Harvard Medical School.