Research published in neuroscience journal eNeuro indicates premature babies are likely to experience developmental delays in the auditory cortex, which was associated with speech and language impairments at two years of age.

Drawing on previous research from ultrasounds of babies in-utero, it has already been determined that foetuses can hear and respond to external stimuli as early as 25 weeks.

“Ultrasound studies reveal, for example, that, beginning at least as early as 25 weeks into gestation, fetuses will blink or move in response to externally produced sounds,” said research leader Professor Brian Monson from University of Illinois.

“Other research shows that newborns prefer to listen to sounds - such as music or speech - that they were exposed to in the womb over unfamiliar sounds. And electroencephalogram studies of the brains of preterm infants show electrical activity in the auditory cortex in response to sound.”

The primary auditory cortex is the first cortical region to receive auditory signals from the ears via the brain, and the non-primary auditory cortex does the processing of the sounds. The research found that the primary auditory cortex develops faster than the non-primary auditory cortex; with the majority of the latter’s development occurring between 26-40 weeks.

"We have a pretty limited understanding of how the auditory brain develops in preterm infants. We know from previous research on full-term newborns that not only are fetuses hearing, but they're also listening and learning."

By looking at the primary auditory cortex in neuroimaging procedures within the infants’ first four days of life, researchers tracked the development of the brain tissue through the comparison of diffusion of water in the brain tissues – where patterns in the grey and white matter change in recognisable patterns, indicating connection development of neurons and axons.

While it was thought some of the babies included in the trial that were placed in open-bay NICU units may have greater primary auditory cortex diffusion versus their counterparts in single-patient rooms – due to the social interaction – no significant observations were measured.

The additional association between the delayed development of the nonprimary auditory cortex in infancy and language delays (but not cognitive functioning) in the children at age 2, suggested that disruptions to this part of the brain as a result of premature birth may contribute to the speech and language problems Professor Monson said.

"It's exciting to me that we may be able to use this technique to help predict later language ability in infants who are born preterm," Professor Monson said. "I hope one day we also will be able to intervene for those infants who may be at greatest risk of language deficits, perhaps even before they begin to use words."