Medical & Biological Engineering & Computing ( IF 2.6 ) Pub Date : 2021-04-02 , DOI: 10.1007/s11517-021-02356-4 Elias Sundström 1 , Liran Oren 1
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The velopharyngeal valve regulates the opening between the nasal and oral cavities. The lack of complete closure is especially problematic in speech because inappropriate leakage of airflow and/or sound into the nasal cavity causes abnormal sound production and increased nasality. The purpose of this study is to use the large eddy simulation approach to examine changes in sound source mechanisms as the size of the opening changes during the production of a sibilant sound. The baseline geometry of the model is based on the pharyngeal airway of a subject having a small velopharyngeal opening while sustaining a sibilant sound. Modifications to the model are done by systematically widening or narrowing the opening (all else being equal). Results show that acoustic energy in the nasal cavity is directly related to the size of the velopharyngeal opening and that there is a critical size where the magnitude of Lighthill’s acoustics source in the nasal cavity is maximized. The far-field acoustic energy and its correlation with the sound source mechanisms are also dependent on the size of the velopharyngeal opening.
Graphical abstract
中文翻译：
不同腭咽开口尺寸的咝咝声中气动声学机制的变化
腭咽瓣调节鼻腔和口腔之间的开口。由于气流和/或声音不适当地泄漏到鼻腔中会导致声音产生异常和鼻音增加，因此在讲话中缺乏完全闭合尤其成问题。本研究的目的是使用大涡模拟方法来检查声源机制在产生咝咝声的过程中随着开口大小的变化而发生的变化。该模型的基线几何形状基于受试者的咽部气道，该受试者的咽部开口较小，同时维持嘶嘶声。通过系统地扩大或缩小开口（所有其他条件相同）来对模型进行修改。结果表明，鼻腔中的声能与腭咽开口的大小直接相关，并且存在一个临界尺寸，使 Lighthill 声源在鼻腔中的幅度最大化。远场声能及其与声源机制的相关性也取决于腭咽开口的大小。
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