ISCA Archive Interspeech 2025
ISCA Archive Interspeech 2025

Acoustic similarities, articulatory uniqueness: Speech production mechanisms in individuals with congenital lip paralysis

Anne Hermes, Ivana Didirková, Philipp Buech, Gilles Vannuscorps

Moebius syndrome is a rare congenital neuromuscular disorder characterized by facial paralysis, which can severely impact speech. Despite these constraints, some individuals with congenital lip paralysis develop very natural speech intelligibility by employing strategies that remain underexplored. This study examines the acoustic-articulatory adaptations in three French-speaking individuals with Moebius syndrome compared to three controls. Using articulatory and acoustic data, we analyzed speech patterns in disyllabic words. Results indicate that Moebius speakers achieve acoustically similar vowel targets to controls despite significant articulatory differences, including increased tongue movement to compensate for lip paralysis. These findings highlight the adaptability of the speech motor system, supporting the notion of motor equivalence in achieving intelligible speech.