Electrical impedance phase variation in relation to articulation manner

This study aims to investigate variations in electrical impedance phase angle due to tongue-palate contact strength induced by different articulation manners. Unlike previous research focusing on pathological conditions, this study examined healthy participants, analyzing impedance phase variations across articulation manners (plain, tense, aspirated) and positions (alveolar, alveolar-post, velar). Tongue pressure, surface electromyography (sEMG), and acoustic features (F2 slope) were simultaneously recorded during articulation tasks, allowing a multidimensional analysis. Six healthy adults (four males and two females) performed consonant pronunciations designed to induce varying tongue tension. A custom-made flexible palatal sensor measured impedance characteristics, which were compared with tongue pressure and sEMG data. Additionally, acoustic analysis was conducted by examining the F2 slope and tongue-palatal contact duration. Results showed that increased tongue contact strength (TCS) led to higher impedance phase angles, elevated tongue pressure, and stronger sEMG signals. Acoustic analysis confirmed that stronger tongue contacts were associated with steeper F2 slopes and shorter contact durations. These findings suggest that the impedance phase may serve as an objective marker of tongue-palatal contact strength and articulation. Although limited by sample size, the findings of this study provide a basis for the development of diagnostic and rehabilitation devices for speech disorders.