Before Kelsea arrives, Conner turns off the fan and air purifier in her office and closes the door to the waiting room so her patient doesn't get distracted by any excess noise.

For a half-hour, the two sit on the floor playing games with shapes, colors and pictures of animals. Conner sits Kelsea right in front of her so that the toddler can see her mouth move as she pronounces words. Simultaneously, she signs words with her hands and points to objects so Kelsea can gain a complete understanding.

"You're bombarding the child with every mode of language so they grasp onto it," Conner said, explaining the method she uses, called "Total Communication."

Kelsea, the daughter of Kim and Damon Knowlton of Niles, was born with a significant hearing loss and a weakness on one side of her face. She has been working with Conner since she was 4 weeks old.

But all parents should keep in mind the techniques Conner uses with Kelsea when they talk to their babies.

Research at Purdue University's Infant Language Laboratory found that even moderate background noise can affect how infants learn language. Sound from the television or of other children playing can pose the same problem for children that older adults with hearing loss encounter at a cocktail party.

And when it's noisy, infants use what they see to interpret sound better, said George Hollich, director of Purdue University's Infant Language Laboratory, who co-authored an article published in the May/June issue in the journal "Child Development."

Seeing facial movements while hearing a person speak can help a child concentrate on the words themselves -- just as older adults who are hard of hearing use their vision to help them understand speech.

Hollich's studies, conducted in 2002 at Johns Hopkins University, where he worked previously, analyzed how environmental noises affect 7-month-olds.

He found that babies respond better to a word if they have just heard and seen it pronounced on a video than if they hear it without seeing corresponding lip movements -- even when there was noise in the background.

"They can actually use what they see to help focus in on that particular voice," Hollich said. "By using what they see, they can deal with noise and distraction."

But for most children, excess background noise might not make much of a difference, Hollich said, since parents speak louder or more clearly or look at their children while they speak when there is excess noise in the background.

But Hollich said more research is needed to evaluate how much infants rely on their vision to supplement their hearing and whether infants need the visual cues when there is no background noise.

He's now researching how older infants deal with noise and distraction when they're learning new words. He's also using robots to predict where infants will look when multiple people are talking.

In the future, Hollich hopes to figure out what a noisy household means for a child's language development.

"There are a few correlations that show the noisier the household, the poorer the child's speech, but it isn't clear because that's so often confused with socioeconomic status," Hollich said. "It's not clear if it was the noise that was the problem or something else."

For some children, such as Kelsea -- who are oversensitive or have hearing impairments -- these strategies are essential for language development, Conner said.

In fact, she said she used them with her older daughter, who had ear infections as a child. But with her younger daughter, they weren't necessary.

"It's just when they start to fail and have trouble that you need to use these strategies," she said. "For normal kids, they usually find another way to get the info or they wait for you to do it again."

"Do kids cope? Are there negative effects? Or are kids able to adjust?" Hollich said. "We think that kids can adjust."

And even though Hollich's study found that even a little noise could affect a child, he said it doesn't mean that parents should be absolutely quiet all of the time.

"Life is noisy, but it's probably a good idea to try to minimize some distractions like background TV or radio," he said. "There'll always be various extraneous sounds."

What does he recommend? A combination of strategies: minimize distractions, speak loudly, speak clearly, and make sure your child can see you. At least that's what he does with his own 3-month-old, Sebastien.

By Sydney Schwartz