2022 Fiscal Year Final Research Report
Physical modeling and excised larynx experiment of vocal-ventricular fold co-oscillations and their implication for singing, medicine, and language evolution
| Project/Area Number |
20K11875
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 61010:Perceptual information processing-related
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| Research Institution | Ritsumeikan University |
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Principal Investigator |
Tokuda Isao 立命館大学, 理工学部, 教授 (00261389)
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| Co-Investigator(Kenkyū-buntansha) |
石村 憲意 立命館大学, 理工学部, 助教 (50779072)
西村 剛 京都大学, 霊長類研究所, 准教授 (80452308)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 仮声帯 / 声帯 / 実体模型 / 摘出喉頭吹鳴実験 / 声帯振動数理モデル / 歌唱 / 生物音響 |
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| Outline of Final Research Achievements |
Co-oscillations of the vocal and ventricular folds were investigated based on the physical modeling of the ventricular folds. The physical model was newly created to imitate physiological features of the human ventricular folds and used for experiments on flow-induced oscillations of the vocal and ventricular folds. Depending upon the conditions set for the distance between the left and right ventricular folds as well as the ventricle size, the vocal and ventricular folds gave rise to synchronized oscillations with various frequency ratios as well as to chaotic desynchronized oscillations. In excised larynx experiments of rhesus macaques, it was again found that the vocal and ventricular folds co-oscillated in synchrony, while, depending upon the experimental condition, chaotic desynchronized oscillations took place. In-vivo experiments of rhesus macaques further suggested that real animals may frequently use the vocal-ventricular fold co-oscillations in their communications.
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| Free Research Field |
非線形動力学
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| Academic Significance and Societal Importance of the Research Achievements |
有声音の発声時に、声帯だけでなく仮声帯も振動する「声帯-仮声帯振動」は、発声障害の一種として長年知られてきたが、近年の歌声研究で、喉歌などの特殊な歌唱でも重要な役割を果たしていることが分かり、ホットな話題となっている。本研究で明らかとなった、声帯と仮声帯の同期振動および非同期振動と、その生成条件は、アンダートーンや、スクリーミング、デスヴォイスなどの歌唱テクニック、さらにはマカクザルの発声を支える共通の物理機構を明らかにしたものであり、音声コミュニケーション分野だけでなく、音楽や生物音響にも新しい知見をもたらした意義深い研究と思われる。
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