A far wider swath of brain areas is activated when children hear their mothers than when they hear other voices, and this brain response predicts a child's social communication ability, researchers including one of Indian-origin have found.

Brain regions that respond more strongly to the mother's voice extend beyond auditory areas to include those involved in emotion and reward processing, social functions, detection of what is personally relevant and face recognition.

The strength of connections between the brain regions activated by the voice of a child's own mother predicted that child's social communication abilities, researchers said.

"Many of our social, language and emotional processes are learned by listening to our mom's voice," said Daniel Abrams from Stanford University in the US.

"But surprisingly little is known about how the brain organises itself around this very important sound source. We did not realise that a mother's voice would have such quick access to so many different brain systems," said Abrams.

Decades of research have shown that children prefer their mother's voices. In one study, one-day-old babies sucked harder on a pacifier when they heard the sound of their mom's voice, as opposed to the voices of other women, researchers said.

The reason behind this preference had never been defined.

"We wanted to know is it just auditory and voice-selective areas that respond differently, or is it more broad in terms of engagement, emotional reactivity and detection of salient stimuli," said Vinod Menon from Stanford University.

The study examined 24 children ages 7 to 12. All had IQs of at least 80, none had any developmental disorders, and all were being raised by their biological mothers.

Parents answered a standard questionnaire about their child's ability to interact and relate with others.

Before the brain scans, each child's mother was recorded saying three nonsense word before the brain scans, each child's mother was recorded saying three nonsense words.

"In this age range, where most children have good language skills, we did not want to use words that had meaning because that would have engaged a whole different set of circuitry in the brain," said Menon.

Two mothers whose children were not being studied, and who had never met any of the children in the study, were also recorded saying the three nonsense words. These recordings were used as controls, researchers said.

The children's brains were scanned via magnetic resonance imaging while they listened to short clips of the nonsense-word recordings, some produced by their own mother and some by the control mothers, researchers said.

Even from very short clips, less than a second long, the children could identify their own mothers' voices with greater than 97 per cent accuracy, they said.

The findings were published in the journal PNAS.