Shiraishi, M.; Mishima, K.; Takekawa, M.; Mori, M.; Umeda, H. An Acoustic Simulation Method of the Japanese Vowels /i/ and /u/ by Using the Boundary Element Method. Acoustics2023, 5, 553-562.
Shiraishi, M.; Mishima, K.; Takekawa, M.; Mori, M.; Umeda, H. An Acoustic Simulation Method of the Japanese Vowels /i/ and /u/ by Using the Boundary Element Method. Acoustics 2023, 5, 553-562.
Shiraishi, M.; Mishima, K.; Takekawa, M.; Mori, M.; Umeda, H. An Acoustic Simulation Method of the Japanese Vowels /i/ and /u/ by Using the Boundary Element Method. Acoustics2023, 5, 553-562.
Shiraishi, M.; Mishima, K.; Takekawa, M.; Mori, M.; Umeda, H. An Acoustic Simulation Method of the Japanese Vowels /i/ and /u/ by Using the Boundary Element Method. Acoustics 2023, 5, 553-562.
Abstract
This study aimed to establish and verify the validity of an acoustic simulation method during sustained phonation of the Japanese vowels /i/ and /u/. The study participants were six healthy adults. First, vocal tract models were constructed based on computed tomography (CT) data, such as the range from the frontal sinus to the glottis, during sustained phonation of /i/ and /u/. Next, cylindrical shapes virtually extended by 12 cm were added to the vocal tract models to imitate the trachea between the tracheal bifurcation and lower part of the glottis. The Kirchhoff–Helmholtz integral equation was formulated as the wave equation for sound propagation, and the boundary element method was used for discretization. As a result, the relative discrimination thresholds of the vowel formant frequencies for /i/ and /u/ against actual voice were 1.1%–10.2% and 0.4%–9.3% for the first formant and 3.9%–7.5% and 5.0%–12.5% for second formant, respectively. In the vocal tract model with nasal coupling, a pole–zero pair was observed at around 500 Hz, and for both /i/ and /u/, a pole–zero pair was observed at around 1000 Hz regardless of the presence or absence of nasal coupling. These findings demonstrated that /i/ and /u/ could be simulated with high validity in a vocal tract model constructed from CT data obtained during sustained phonation using the boundary element method.
Keywords
articulation; acoustic simulation; boundary element method; vocal tract model; Japanese vowels
Subject
Medicine and Pharmacology, Dentistry and Oral Surgery
Copyright:
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