In order to investigate the characteristics and reproducibility of the mandibular position during phonation of a Japanese syllabary single sound, intra- and inter-individual variations of the mandibular position were analyzed in 10 normal subjects using the Sirognathograph Analyzing System.
Results were summerized as follows:
1. With regard to the characteristics of the mandibular position during phonation of each vowel pronunciation, the order of the amount of the mandibular displacement in the vertical and anterior-posterior directions from maximum to minimum was IA/, /E/, /O/, /I/, and /U/ vowel pronunciation.
2. With regard to the characteristics of the mandibular position during phonation of each consonant pronunciation, IS/ consonant pronunciation showed the smallest mandibular displacement in the vertical and anterior-posterior directions of all the consonant pronunciation.
3. Phonation of each distinct single sound was performed at each characteristic mandibular position. However, high degree of reproducibility of the mandibular position during phonation was demonstrated in every subjects.
4. The mandibular position during phonation of a Japanese syllabary has a little inter-individual variations in both antero-posterior and lateral direction. However, they showed a large inter -individual variation in superio-inferior direction.
