U of T researchers call for new approach to speech sound disorders in children
Researchers at the University of Toronto are urging a reconsideration of how children are assessed for speech sound disorders, a group of conditions that make the correct pronunciation of words difficult.
They say mounting evidence suggests more of these disorders result from motor-based problems of the jaw, lips and tongue than previously realized, rather than from cognitive-linguistic issues only, such as sound processing and memory function.
Their call, recently published in Frontiers in Human Neuroscience, challenges long-held beliefs in the field of rehabilitation science, and raises questions about a reliance on clinical assessments of children that use language-based, aural-perceptual tests.
“This is a fundamental shift in the way we understand and approach speech sound disorders in children,” said Aravind Namasivayam, first author of the paper and adjunct professor of speech-language pathology at U of T’s Temerty Faculty of Medicine.
“Growing evidence suggests language processing and production in children is multidimensional. Several speech motor and linguistic factors play a key role in speech sound problems, but auditory-perceptual assessments often miss subtle indicators such as phonetic differences and tongue movement patterns,” Namasivayam said.
Historically, clinicians have focused almost entirely on listening to children speak and then categorizing what is heard, said Namasivayam. “These methods were designed to describe speech, however, they rely on a clinician’s ear and subjective assessment and aren’t designed to identify underlying contributing factors such as motor control of speech-related movements,” he said.
Motor control issues related to speech production can be identified using modern, instrument-based assessments, such as different imaging techniques and acoustic analysis.
Recent research that incorporates instrumental approaches, including a randomized controlled trial by Namasivayam and colleagues, has started to reveal new detail on how the jaw, lips and tongue move when speaking and their relationship to speech sound errors.
The U of T-led trial showed that pronunciation errors such as cluster reduction (oversimplifying complex sounds), consonant deletion, and stops in speech, were strongly associated with speech-motor limitations in 48 pre-school children with moderate or severe speech sound disorders.
“Relying solely on listening tests and categorical frameworks oversimplifies the true nature of paediatric speech sound disorders,” said Pascal van Lieshout, senior investigator on the study and a professor of speech-language pathology at Temerty Medicine.
“To get a clear picture of what is happening, clinicians need to consider the many dimensions of speech sound disorders and supplement listening approaches with other methods of assessment. We understand that it may be challenging for clinicians to use more instrument-based assessments in their daily practices, but their value is highlighted by our recent findings.”
A better understanding of a child’s individual speech sound disorder can enable clinicians to offer more precise and tailored therapy, van Lieshout noted.
For five-year-old Zach*, three years of traditional speech-therapy approaches were ineffective; he was unable to articulate words clearly enough to be understood. Worried that he would be bullied when he started school, his mom decided to try motor-based speech therapy for him.
Using ultrasound technology to visualize Zach's tongue movements while speaking, his speech-language pathologist was able to identify underlying motor-control issues contributing to his struggles with pronunciation. Subsequent sessions focused on using ultrasound technology to teach Zach how to move his tongue to produce accurate speech.
He’s made “a wild amount of progress,” said his mother. “Before, I would be in tears very often, just very worried for his future, but now I’m not. He’s having full back and forth conversations with others and his speech doesn’t impact him at school. We’re seeing an explosion in his progress.”
Adopting a multidimensional approach and using comprehensive assessment tools means that children like Zach can receive interventions that are personalized to meet their unique needs. This in turn makes intervention outcomes more person-centred and functional.
“This is an exciting time to be in the field of speech-language pathology,” said Namasivayam. “The profession is on the cusp of entering a new era of precision medicine — one in which speech therapy can be tailored to each child, fostering improved speech outcomes and better overall health.”
*Name has been changed to protect privacy
The clinical trial mentioned in this story was funded by the Natural Science and Engineering Research Council of Canada and the National Institutes of Health in the U.S.
