TO THE newborn baby, there's nothing like their mother's voice. Brain scans have revealed that their brain reacts in a very unique way when they hear it. No other sound on Earth causes this reaction.
To psychologists, it's the sound that triggers the language learning process in an infant. But it's responsible for so much more than that. In February, the results of two very different studies confirmed the importance of a mother's voice to premature babies.
At Vanderbilt University Medical Centre, Nashville, the mother of each premature baby was recorded singing a lullaby. The recording was installed on a music player that was connected to a special dummy. When the baby sucked on the dummy, she would hear her mother singing the lullaby.
The babies were given this treatment for 15 minutes a day. After only five days, the researchers found that the babies ate more frequently and had developed stronger sucking ability. They had their feeding tubes removed one week earlier than the babies who hadn't received the treatment, and they required less time in hospital.
"A mother's voice is a powerful auditory cue," said Dr Nathalie Maitre, professor of paediatrics at Vanderbilt University. "Babies know and love their mother's voice. It has proven to be the perfect incentive to help motivate these babies."
At Brown University, Rhode Island, Dr Betty Vohr found that babies vocalised more when their mothers were in the neonatal intensive care unit (NICU) with them. And when she monitored the amount of talk premature babies were exposed to while on the NICU, she found that those who were talked to more had better language and cognitive abilities when tested at 18 months. "Our study demonstrates the powerful impact of parents visiting and talking to their infants in the NICU on their developmental outcomes," said Dr Vohr.
"Historically, very premature infants are at increased risk of language delay. The study now identifies an easy to implement and cost effective intervention – come talk and sing to your baby – to improve outcomes."
However, for many Irish mums, science is merely confirming their own experiences.
"My twins were born 10 weeks early in February 2009. It was a very stressful time as my mum had passed away five months previously. I had no one with me at the ICU, so I spent my days talking to the boys," says Rachel Hearne.
"My two were very feisty, despite being small, and constantly pulled out their feeding tubes. While the nurses reinserted the tubes, I would speak to them and they would relax."
On one occasion, while the nurses were moving Rachel's twins, the smallest boy became very agitated. Medical alarms were sounding and the nurses were struggling to calm him.
"I walked over and spoke to him. He just stopped, instantly, and turned to me. I couldn't believe it. From that moment on I spoke and sang songs to them."
When Tina Fitzpatrick's son, AJ, was born in June 1988, he weighed only 3.5 pounds and was given only a 5 per cent chance of survival.
"He had a life-saving operation for a congenital diaphragmatic hernia; and a second operation for two lower-abdominal hernias when he weighed seven pounds," she says.
Little AJ was kept sedated and was receiving 100 per cent oxygen.
"We were not allowed to touch him for the first month, so we talked to him non-stop. After he woke up, we stroked him all day and talked to him to let him know we were there."
Little AJ is now a 25-year-old PhD student, and an ambassador for University College Dublin.
However, talking doesn't just benefit the baby, it allows a parent to make a contribution at a time when they may feel helpless.
When Liam Kirby was born in November 2013, he was seven weeks premature and had a bleed on his brain. It was a frightening time, but new mum Deirdre did what she could to help Liam – and it helped her get through the experience.
"The only two things I could do were express milk and talk to Liam," she says. "We kept a constant vigil by his incubator and kept talking to him. I started making up stories. We even promised to take him to Disney World. The nurses laughed at that. But it was a comfort."
Jan Redmond took a similar approach when her son was born at only 24 weeks.
"I spoke to him all the time in the neonatal, reading stories to him and reading speeches of world heroes. I thought it helped him and me bond. He's doing very well now, with little or no problems, and he loves books and storytelling and superheroes."
The influence of a mother's voice isn't confined to the NICU. A mother talking to her infant is fundamental to the development of language skills. Good language skills are essential for cognitive development and, consequently, good academic achievement.
But studies have found that many infants from low-income families have poor language skills. By the time they reach primary school, some of these children can be two years behind in terms of their language ability, and this directly affects their learning ability.
However, Anne Fernald, a professor of psychology at Stanford University, doesn't believe money is the problem. She believes this gap in ability is caused by how mothers talk to their children. Fernald found that infants whose parents spent time talking to them had greater language skills than those whose parents didn't.
Fernald's findings have led to the creation of a programme in California that teaches low-income mothers how to engage and talk to their children. To help them help their children to develop good language skills and – as a consequence – their brains.
"What's exciting," said Professor Fernald, "is that by 24 months the children of more engaged moms are developing bigger vocabularies and processing spoken language more efficiently. Our goal is to help parents understand that by starting in infancy they can play a role in changing their children's life trajectories."
Other studies have found that good language skills in infancy are the key to other important skills – such as perseverance, attentiveness, motivation and self-confidence.
A study by Pennsylvania State University found that infants with early language skills were better able to manage their anger when older. Children in the study were given a number of tests, each designed to cause frustration. The researchers monitored how each child dealt with this frustration.
In one test, each child was given a gift. The child was instructed not to open the gift until her mother had completed a task with the researcher. This task lasted exactly eight minutes, and the researchers monitored how each child coped with the wait.
The researchers found that those children who had developed better language skills as toddlers were better able to occupy themselves during the wait and, when they did become frustrated, were more likely to verbalise this frustration and less likely to throw a tantrum.
So, how should you talk to your infant to ensure their healthy development? Dr Jean Quigley and Dr Sinéad McNally of the School of Psychology, Trinity College Dublin, have been looking into this question. By carefully analysing videotaped interactions between mothers and their infants, they have obtained some valuable insights.
"The most important thing is to talk to infants as much as possible," says Dr Quigley. "But, it's not just quantity – quality matters a lot.
"Some mothers are quiet, some are quite chatty. The important aspect, really, is that they interact with their child in a way that's both contingent and responsive. That is, what you say is reflective of what the baby is doing. The child has to be engaged in order to learn."
Babies love to hear baby-talk, known in the trade as infant directed speech (IDS). "Infant directed speech is something we instinctively do," says Dr McNally. "But, there is strong evidence that IDS benefits language development. For example, research has found that infants listening to IDS display higher neural brain activity than they do while listening to adult directed speech.
"Speech that engages the infant and encourages back and forth communication is also going to be particularly important in language development and acquisition," she says.
"It's important to attract the infant's attention to the face – the eyes and mouth," says Dr Quigley. "Typically, when using IDS, we use a very animated face with wide eyes and open mouth – which helps with language acquisition and development."
That babies are so affected by their mothers' voices is no accident. From birth, a baby's brain reacts to human noises – even coughs and sneezes – in a way that's different to non-human noises. But it has been shown that their brains react in a very unique way when listening to their mothers. At the University of Montreal, brain scans revealed that, while infants reacted to all women's voices, only the mother's voice triggered the language learning parts of the brain. Dr Maryse Lassonde led this research.
"This is exciting research that proves for the first time that the newborn's brain responds strongly to the mother's voice and shows, scientifically speaking, that the mother's voice is special to babies."