OKLAHOMA CITY, OK — When people cannot hear their own voices, their tongue movements become less precise during speech, according to new research from the University of Oklahoma. The findings provide direct evidence of how hearing contributes to speech production and may help inform therapies for individuals with hearing loss or those affected by conditions such as tongue cancer.
The study, led by Matthew Masapollo, Ph.D., assistant professor at the OU College of Allied Health, was published in the Journal of Speech, Language, and Hearing Research. It addresses a longstanding question in neuroscience: how much auditory feedback contributes to speech motor control.
“Speech feels automatic, but it’s one of the most complex motor skills that we routinely perform. A typical adult produces up to 16,000 words each day – that’s tens of thousands of precisely timed movements requiring precise coordination throughout the vocal tract. What we’ve shown in this study is that auditory information helps regulate the control of the movements.”
–Matthew Masapollo, Ph.D
Tracking Tongue and Jaw Movements
In the study, participants spoke both with and without the ability to hear their own voice. Researchers used electromagnetic articulography—small sensors placed on the tongue and jaw—to track movement as participants produced speech sounds such as “ta” and “da.”
The results showed a specific effect: when auditory feedback was masked, tongue-elevating movements—those that press the tongue against the roof of the mouth—became less precise and more variable, while jaw motion remained unaffected.
“The effect was strongest during tongue-elevating movements, rather than overall tongue motion,” Masapollo said. “This suggests the brain doesn’t fully pre-plan speech movements; it also relies on real-time sensory information to regulate tongue movements for speech.”
Why the Tongue Matters
Compared to the jaw, which primarily rotates up and down, the tongue is highly flexible and requires more precise control. The study suggests that this flexibility increases reliance on sensory input, including auditory feedback, to guide speech production.
These findings may be particularly relevant for individuals with hearing loss, including cochlear implant users, as well as patients undergoing treatment for tongue cancer.
Implications for Rehabilitation
The research is also informing an ongoing study involving patients treated for tongue cancer at the OU Health Stephenson Cancer Center. Treatments such as surgery, chemotherapy, and radiation can affect both hearing and tongue function, creating additional challenges for speech and swallowing.
“The sensory nerves of the tongue are often damaged during surgery, and radiation creates a lot of fibrous tissue in the tongue,” he said.
“People who have part of their tongue removed may also have trouble swallowing. When we swallow, the tongue rises to press against the roof of the mouth, forming a tight seal – similar to the tongue movements used to produce the sounds ‘ta’ or ‘da’. This seal helps guide and control the movement of food and liquid during swallowing, just as precise tongue positioning is critical for producing speech.”
Masapollo plans to follow participants before and after treatment over a three-year period to better understand how different interventions affect tongue control and motor function. The goal is to support improved rehabilitation strategies for speech-language pathologists and related clinicians.
Advancing Measurement in Speech Research
The study also highlights the value of advanced measurement tools in speech science. Electromagnetic articulography allows researchers to directly observe movements within the vocal tract—something not possible with traditional perceptual or acoustic analysis alone.
“Previous studies have relied almost exclusively on subjective perceptual ratings of speech,” Masapollo said. “This is the first direct evidence that auditory input specifically affects the speech-related motion of the tongue. You wouldn’t be able to infer that from just listening to someone or even doing an acoustic analysis of speech. You have to directly observe the movements hidden within the inner reaches of the vocal tract, which we are now able to do.”
About the Project
The publication, “Precision of Tongue Control for Task-Relevant Articulatory Goals Diminishes Without Real-Time Auditory Feedback,” can be found at https://doi/10.1044/2025_JSLHR-25-00514. Masapollo’s collaborators on the study of tongue cancer patients include Peter Keates, DMA, CCC-SLP, Rusha Patel, M.D., and Christina Henson, M.D.
About the University of Oklahoma
Founded in 1890, the University of Oklahoma is a public research university with campuses in Norman, Oklahoma City and Tulsa. As the state’s flagship university, OU serves the educational, cultural, economic and health care needs of the state, region and nation. In Oklahoma City, the OU Health Campus is one of the nation’s few academic health centers with seven health profession colleges located on the same campus. The OU Health Campus serves approximately 4,000 students in more than 70 undergraduate and graduate degree programs spanning Oklahoma City and Tulsa and is the leading research institution in Oklahoma. For more information about the OU Health Campus, visit www.ouhsc.edu.
Source: OU
