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A recent study from McGill University has revealed that hearing plays a pivotal role in how humans control and coordinate speech movements in real-time. Published in The Journal of the Acoustical Society of America, the research highlights that even temporary disruptions in hearing can significantly impair speech production by affecting the precise movements of the jaw and tongue.
The study, led by Matthew Masapollo, a former Research Associate at McGill’s Motor Neuroscience Laboratory, shows that when individuals cannot hear their own speech, their ability to speak with coordinated mouth movements is hindered. “People rely on immediate auditory feedback to coordinate and control the movements of their vocal tract for speech production,” said Masapollo.
Methodology and Key Findings
To explore the connection between hearing and speech motor control, the research team employed electromagnetic articulography (EMA) to track jaw and tongue-tip movements. Participants with normal hearing were asked to speak under two different conditions: one where they could hear their own speech and another where their speech was masked by multi-talker noise, simulating a brief loss of hearing feedback. Under the latter condition, speech motor performance noticeably declined.
This study emphasizes the critical role of auditory feedback in maintaining smooth, coordinated speech. When individuals cannot hear themselves, even momentarily, it disrupts their ability to control key articulators, such as the tongue and jaw, which are essential for producing clear speech.
Implications for People with Hearing Loss
These findings have far-reaching implications for individuals with hearing loss, particularly those using cochlear implants (CIs). Masapollo explained that despite the benefits of cochlear implants, some aspects of speech production remain impaired even years after implantation, likely due to the degraded auditory signals provided by CIs.
In collaboration with other researchers, including Susan Nittrouer and McGill professors David J. Ostry and Lucie Ménard, Masapollo is now investigating how reduced auditory access through CIs affects speech coordination in implant recipients. Preliminary results indicate that people with hearing loss may rely more on tactile feedback—such as how their tongue and mouth feel—rather than auditory feedback to control speech.
Future Clinical Applications
These insights could lead to new therapeutic interventions, focusing on oral-motor training, to assist individuals with hearing loss, particularly children learning to speak. By emphasizing tactile sensations in speech production, clinicians may be able to better support those using cochlear implants or suffering from severe hearing impairments.
The research underscores the complexity of speech production and the importance of real-time auditory feedback, offering hope for future advancements in speech therapy and auditory rehabilitation.
For more details on the study, the full paper titled Immediate Auditory Feedback Regulates Inter-Articulator Speech Coordination in Service to Phonetic Structure is available in The Journal of the Acoustical Society of America.
Reference
Masapollo, M., et al. (2024). Immediate auditory feedback regulates inter-articulator speech coordination in service to phonetic structure. The Journal of the Acoustical Society of America. DOI: 10.1121/10.0028725
