Infants tend to hear more of their mothers' speech early in life than their fathers', according to a new study. Dr. Betty Vohr, a pediatrics professor at the Warren Alpert Medical School of Brown University, said that this imbalance may be why infants tend to respond more strongly to the sound of their mother's voice than their father's.

The research paper was published today, November 3, in the journal Pediatrics.

Vohr said that the team is not yet sure why this happens, but said that these findings may reveal something important about the way we raise our children, since early speech recognition is a crucial part of development.

Vohr's team studied 33 babies by attaching a small recorder to a vest that babies wore for at least 10 hours. The researchers recorded the babies three times: once just after they were born, once when they were about one month old, and once when they were seven months old. (To equalize the age for premature babies, age was determined based on time of conception, not time of birth.)

The researchers found that when babies babbled, mothers responded to them vocally about 88% to 94% of the time, while fathers only responded vocally 27% to 33%.

The researchers found that both male and female babies responded better to female voices than to male voices. This may be because women tend to talk to infants in "baby talk" more often than men, or because women make more eye contact while talking to babies than men.

The researchers also found that men who had sons tended to respond to their babies slightly more often than men who had daughters, although Vohr said there wasn't enough data on this point to be conclusive. The team also found that women responded to their own daughters slightly more often than woman who had sons.

Whatever these results might mean, Vohr stressed the importance of talking to your baby as often as possible early in life.

"It seems to me that adults talking to children is absolutely the most cost effective intervention a family could do to improve children's language," Vohr said.