Predicting Speech Intelligibility Based on Spatial Tongue–Jaw Coupling in Persons With Amyotrophic Lateral Sclerosis: The Impact of Tongue Weakness and Jaw Adaptation

What is it about?

Motor neuron diseases, such as ALS, have a devastating effect on speech muscle function, resulting in abnormal movements of the speech organs (e.g., tongue, jaw) and difficulty in speech production. We investigate the relation of the disease-related changes in tongue and jaw movements to speech intelligibility in persons at different stages of ALS. Our findings suggest that individuals at the early stages of ALS increased their jaw movement to compensate for the reduction of tongue movement so that their speech remained relatively intelligible. However, individuals at the late stages of ALS were no longer able to make such compensations, resulting in a sharp decline in speech intelligibility. Therefore, the loss of jaw compensation is likely to be a critical factor that leads to the eventual loss of functional speech in ALS.

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