By Linda Carroll for TODAY
Many dads are spending a lot of time with their little ones these days, but even with all that bonding time, they haven't picked up baby-talk, according to the first study to examine fathers' verbal interactions with their children in a real-world setting.
Cooing, high-pitched vocalizations are exclusive to moms, according to the study presented at the annual meeting of the Acoustical Society of America.
"It's not that dads can't or never do it," says the study's lead author Mark VanDam, a professor at Washington State University. "But on the whole they do less of it. We don't know why."
VanDam and his colleagues outfitted preschoolers and their parents with recording devices to monitor how families communicated during the course of a normal day. They used speech-recognition software to analyze the details of how parents were talking to their kids.
The study results echoed earlier research showing that moms tend to vary the tone of their voices, often speaking in a higher pitch than they do with adults. Dads, instead, speak to their children using intonation patterns similar to what they use when speaking with other adults.
"With respect to the actual difference, it is substantial," VanDam says. "Mothers are about 40 Hz higher when using [baby-talk] and dads show no difference" between talking to a child and talking to an adult.
A 2014 study in Pediatrics found that infants from birth to 7 months were exposed to significantly more cooing and words from mom than dad.
Maybe baby babble is just not a guy thing.
Jason Jepson, whose 25 hour work week allows him to be primary caregiver for his daughter, Harper, says his wife is the one who uses baby-talk.
"I talk to my kid like an adult," says the 40-year-old dad from Austin, Texas. "She's 21 months old now and I've been talking to her this way since she was born. Baby-talk isn't my personality."
"My wife is different. When she's playing with Harper, she's doing baby-talk, and I love it. I think we have a great healthy balance."
Eschewing baby-talk doesn't mean there's no fun time, Jepson says. "What I replace baby-talk with is tickling and roughhousing around," he explains. "I rub the bottoms of her feet on my beard and it tickles."
And then again, it might cultural.
Greg Bryant has been looking at how dads from different cultures communicate with their offspring. While North American fathers don't vary tone when talking to their kids, Fijian dads do.
And while North American dads slow down their speech when talking to a baby, Fijian dads don't, says Bryant, an associate professor of communications at the University of California, Los Angeles.
Experts say the point of varying tone and speaking in a high pitch is to grab a young child's attention.
"The downside to children between 0 and 15 months being talked to in a normal adult intonation is that infants are less likely to [be attentive] and less likely to learn," says Catherine Snow, a professor at the Harvard Graduate School of Education. "Talking with an exaggerated intonation alerts babies that you are talking to them. They learn more from talk that is adapted to their needs."
Jepson gets his daughter's attention by making eye contact.
"I ask her to look at me," he explains. "And oddly enough she grabs my face and makes me look at her when she has something to say."
VanDam doesn't think men need to start using baby-talk if they're not comfortable with it. "We don't interpret this as a failure," he says. "It's not like men are not doing something they are supposed to be doing. In fact, there is a hypothesis that dads provide a link to the outside world."
No one knows to what extent baby-talk might help young children pick up language skills, Bryant says. "It helps with emotional communications," he adds. "Some say that it has no effect in helping kids learn the language. Others say it helps them learn syntax and vowels. The answer is probably in between."
Linda Carroll is a regular contributor to NBCNews.com and TODAY.com. She is co-author of "The Concussion Crisis: Anatomy of a Silent Epidemic" and the recently published "Duel for the Crown: Affirmed, Alydar, and Racing's Greatest Rivalry"