ABSTRACT
The tongue and larynx interact with each other during speech because they are connected with connective tissues via the hyoid bone. This biomechanical interaction derives small but consistent vowel-dependent variations of the voice fundamental frequency (F0) known as the “intrinsic vowel F0.” This study aims to explore the chain of mechanisms of the tongue-larynx interaction using high-resolution MRI with a custom larynx coil and phonation-synchronized method. Experiments were performed on two male subjects during the production of sustained vowels /a/ and /i/ with high, mid, and low F0 values, with the result demonstrating both individual differences and similarities among them. The differences were found in jaw position and vertical position of the hyoid-larynx complex, while the similarities were in tight hyoid-larynx linkage. The tongue root and the hyoid bone were more advanced in vowel /i/ than in vowel /a/. At a higher F0, the hyoid-larynx complex was more forward and upward, while jaw position varied between subjects. It was suggested that the movement of the hyoid-larynx complex is caused by contraction of the genioglossus and geniohyoid muscles, but not by jaw position.
