Biomechanical modeling of English /r/ variants

We report our investigation of the well-known context-dependent variation in English /r/ using a biomechanical tongue-jaw-hyoid model created in the ArtiSynth toolkit, a 3D biomechanical simulator of the human vocal tract. We show that preferred /r/ variants require less volume displacement, relative strain, and relative muscle stress than variants that are not preferred. Our study also uncovers a previously unknown mechanism in tongue biomechanics that is important in /r/ production: Torque in the sagittal plane about the mental spine. This torque enables raising of the tongue anterior for a retroflexed [õ] adjacent to /a/ using primarily hyoglossus (HG) and relaxation of anterior genioglossus (GGa). The results provide a deeper understanding of the articulatory factors that govern contextual phonetic variation.