Toddlers make their fair share of noise. But they also have a lot of noise to contend with — a television blaring, siblings squabbling, a car radio blasting, grownups talking.
Amid all that clatter, toddlers must somehow piece together the meanings of individual words and start to form their own words and sentences.
Loud background noise may make it harder for toddlers to learn language, according to a study published Thursday in the journal Child Development. Many other studies have already found that background noise can limit children's abilities to learn. Television noise, in particular, is ubiquitous in American homes and may negatively affect a child's ability to concentrate.
But few researchers have looked at how background noise affects toddlers as they are just beginning to learn words.
Learning words early is important and can affect basic reading skills later on, says Brianna McMillan, a psychology graduate student at the University of Wisconsin-Madison and lead author on the study. "These initial word learning experiences are very foundational for how kids succeed later in life."
McMillan and her graduate adviser, professor of psychology Jenny Saffran, tested whether louder or quieter background speech affected whether toddlers at about 23 months could learn new words.
A group of 40 toddlers listened to recordings of new words in sentences. At the same time, they also heard background speech — recordings that sounded like two people speaking at once. The researchers say that this background recording could represent people chatting in the same room or on the television or radio.
Half of the toddlers heard louder background talk — "like having a conversation with a friend while someone else is standing a foot away talking," explains McMillan. The other half heard the same recording at a quieter decibel — "more akin to background coffeehouse chatter," she says.
With the background noise still playing, the researchers then taught the toddlers the meanings of the new words by showing them images on a screen of what each word represents.
The scientists then tested how well each group of toddlers had learned the new words.
It turned out that toddlers could only learn new words when the background chatter was quieter.
The researchers tried the same experiment on a group of 40 toddlers who were about six months older and found the same result.
In a final experiment, the scientists allowed 26 toddlers to hear new words in sentences in a quiet room and then taught them the meanings of the words under the louder background noise condition. This group of toddlers did successfully learn the new words.
This last experiment provides some hope that carving out a bit of quiet time for learning words can help children attach meaning to those words later in their more typical noisy environments.
"It's not practical to completely turn off the radio or TV all the time," says McMillan. "I don't think that's how we can or should live." But she says that parents might want to be more aware of what their kids are hearing and turn off the TV now and then.
It's unclear whether the Wisconsin team's findings would hold true for a broader group of toddlers from across the United States — this study focused on a fairly small group from an area with a large university community.
But the Wisconsin team's research covers an important under-studied area, says Rochelle Newman, chair of the Department of Hearing and Speech Sciences and associate director of the Maryland Language Science Center at the University of Maryland. "There's been a lot of work on noise and its impact on learning once children reach the age of schooling. A lot less has been done on younger children," she says.
Newman says there are still many unanswered questions, including whether some level of noise might be beneficial for toddlers in the long term.
"Children are going to go to school where there is a lot of noise," Newman says. "They're going to eventually have to learn to deal with that noise. We don't know if they'll need some exposure to learn to deal with it. We don't know how much is too much noise."