A multivariate toolkit for joint articulatory-acoustic analysis with an application to coarticulation.

This study presents an integrated methodology for analyzing the effects of coarticulation on both articulatory and acoustic properties of phoneme sequences. The approach combines co-registered real-time magnetic resonance imaging (MRI) and acoustic recordings, applying geometric morphometric analysis to articulatory postures and Mel-frequency cepstral coefficient analysis to the corresponding speech signal. As a case study, coarticulation in vowel-consonant-vowel (VCV) sequences is examined. The results show that coarticulation induces substantial shifts in consonant postures and acoustics toward adjacent vowels, while vowel postures exhibit only minor displacement toward consonants. Despite these context-driven displacements, phonemic contrasts between vowels and between consonants remain largely intact, suggesting that speech production maintains category distinctiveness through stable relational geometries rather than fixed articulatory positions.