Dads 'use adult tone not baby talk'
Mothers are more likely to coo at their babies, while fathers address them more like small adults - but both approaches help children learn, a study suggests.
Scientists at Washington State University used speech recognition software to analyse differences in parents' speech patterns.
Mothers' "baby talk" is believed to promote bonding.
But fathers, who use a more adult tone with babies, may provide a "bridge" to the outside world, the researchers say.
The researchers analysed hundreds of hours of family speech, including mothers, fathers and their pre-school children.
Families wore microphones, and their interactions were recorded over the course of a normal day.
The research detected distinct differences between the ways mothers and fathers spoke to their pre-school children.
Mothers used a voice that was higher and more varied in pitch than the tone they used when addressing other adults.
"Baby talk", sometimes referred to as "Motherese", has exaggerated, attention-catching cadences, which are attractive to babies and young children.
Fathers, by contrast, used intonation patterns more similar to those they used when speaking to adult friends and colleagues.
But this did not imply fathers were failing to engage with their children, said lead researcher Mark VanDam, professor of speech and hearing sciences at Washington State University.
"This isn't a bad thing at all. It's not a failing of the fathers," said Prof VanDam.
He suggested the different approach could help children deal with unfamiliar speech patterns and acquire language as they grew up.
"We think that maybe fathers are doing things that are conducive to their children's learning but in a different way," said Prof VanDam.
"The parents are complementary to their children's language learning."
He added that although fathers were less likely to use "baby talk", this did not prevent them modifying their speech in other ways, for example by using simplified vocabulary or changing the volume or duration of what they were saying.
The research included only families with a mother and father who both lived full-time with the child, so it did not look at how the results might differ in single-parent families or those headed by same-sex couples.
The university says this is the first study to examine fathers' verbal interactions with their children in a real-world setting - most research has so far focused on mothers.
It is part of a larger programme to examine how fathers support children's language development in infancy and early childhood.
The findings have been presented to the annual meeting of the Acoustical Society of America, in Pittsburgh, Pennsylvania.