The Effect of Tongue–Jaw Coupling on Phonetic Distinctiveness of Vowels in Amyotrophic Lateral Sclerosis

What is it about?

Loss of speech sound distinctions due to bulbar (i.e., speech and swallowing) motor involvement is a primary cause of speech loss in persons with Amyotrophic Lateral Sclerosis (ALS). This study finds that the coupling between the tongue and the jaw, which are two important articulators for speech production, has a significant impact on the distinctiveness of vowels. During the early and middle stages of bulbar ALS, the coupling between the tongue and the jaw can be adjusted to accommodate the disease effect on the articulators so that the phonetic distinctiveness of vowels is affected only to a limited extent. Yet, when the disease progresses to the late stage, such adaptations are no longer possible, leading to a substantial reduction of vowel distinctiveness.

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