Before children speak their first words, the sounds they hear shape how they’ll learn, think and connect with others.
Kristin Uhler, PhD, associate professor of physical medicine and rehabilitation at the University of Colorado School of Medicine, is researching how an infant’s ability to hear the differences between two speech sounds impacts language outcomes. Her work shines light on how language develops and may inform future interventions to address the challenges children with hearing differences face.
Using brainwaves to understand infant hearing
Babies can’t tell you what they can hear. But with the help of colleagues, Uhler is able to measure a baby’s brainwaves to see how changes in speech sounds are encoded and to test if babies can indicate with their behavior that they hear a change in speech sounds (AKA speech discrimination).
“We have been able to teach babies to turn their heads toward a sound, which is then reinforced visually by seeing a video,” she said. Babies were taught to differentiate between different types of sounds, such as Ba and Da or Ahhh and Eeee.
Uhler and her team have been following how babies discriminate or differentiate these speech sounds at 3, 6 and 9 months of age and then comparing the findings to how language develops at 30-33 months of age.
At this stage, early interventionists and pediatricians measure toddlers’ language development using standardized parent questionnaires. The findings are important, as they often have implications regarding whether a child receives early intervention services for hearing loss. But these surveys do not provide information about the number of words a child uses or how complex and spontaneous language is developing. They also don't provide clues as to how the child’s brain is processing speech. The test that Uhler and her team are developing is intended to fill this gap.
They know the same number of words, but …
“Spontaneous language” samples taken at 33 months of age reveal a difference between children with typical hearing and those with hearing differences. The samples – 25-minute audio and video recordings of kids interacting with a primary care provider – provide a “more ecologically valid” way of seeing how children use spoken language.
From a quantity perspective, children with hearing differences tend to know the same number of words as their typical hearing peers. They can “label” people, places and things. But Uhler's recent work illustrates that they use fewer verbs – the fundamental action words that form the basis of communication.
“If you’re not able to use verbs, you can’t string two words together,” she said. “When it comes to being able to communicate, we need language that goes beyond the labeling of things.”
The samples give researchers an opportunity to analyze the language skills that children with hearing differences use and how they use them in their daily life.
“It’s an area that’s hard for parents, as every parent wants their child to be treated well. Understanding this problem challenge from a research perspective is so important, so we can create interventions to help kids with hearing differences overcome these challenges.” – Kristin Uhler, PhD
The impact on advanced thinking skills
By the time children with hearing differences reach preschool, they tend to show delays in how they use social language, as compared to their typical hearing peers. The language samples demonstrate delays in using pragmatic skills – also referred to as social language – at 33 months.
Early childhood is also when the foundational skill of being able to think about what others are thinking begins to develop. To illustrate, Uhler uses an example of showing an 18-month-old a box of crayons.
“If you ask the child what’s in the box, she’ll say crayons. But then you show her that you’ve hidden chocolate in the box. Then you ask the child what her friend would think was in the box. At 18 months, she’ll say chocolate. As she gets older – around her fourth birthday – she’ll understand that the friend will see the box of crayons and guess there are crayons inside.”
This change shows the child’s ability to think about what other people know or don’t know, which is a key part of how humans develop advanced thinking skills – skills important in making friends, Uhler said.
Did you know? Untreated hearing loss has been linked to dementia.
Research supports early intervention
The ability to think about how another person feels and form friendships starts early on, by watching and listening to the interactions of our parents and peers, Uhler said. Her work is identifying an opportunity for growth in providing early interventions for children with hearing differences.
“It’s an area that’s hard for parents, as every parent wants their child to be treated well. Understanding this problem challenge from a research perspective is so important, so we can create interventions to help kids with hearing differences overcome these challenges,” she said.
Identifying that children with hearing differences use the same number of words but not as many verbs compared to their typical hearing peers is a start toward creating meaningful intervention.
“Right now, it’s important for us to continue figuring out the relationship between early speech discrimination abilities and language,” she said. “Using more ecologically valid tools like language samples can help us learn more about how that impacts a child's ability to develop these pragmatic skills, which impact friendship building.”
May is National Speech-Language Hearing Month
Communication disorders can affect anyone at any age. Common conditions such as hearing loss, voice disorders, speech delays and stuttering can impact learning, relationships and even employment.
By the numbers:
- One in 12 children in the U.S. has a disorder related to speech, language, voice or swallowing, which impacts a child’s learning, expression and interactions with others.
- One in eight people in the U.S. over age 12 has hearing loss in both ears.
- Five to 10% of preschoolers have a delay in speech or language that requires professional support. Once they reach school age, 7-8% still have challenges understanding or using language.
- Boys are affected more than girls.
The good news is that help is available and highly impactful, thanks to speech-language pathologists, audiologists and researchers. Early identification and support can help children catch up and thrive.
