Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267, USA.
Med Biol Eng Comput. 2021 Apr;59(4):937-945. doi: 10.1007/s11517-021-02356-4. Epub 2021 Apr 2.
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. Patient-specific geometry with a velopharyngeal opening during a normal sibilant /s/ sound is shown to the left. Lighthill's acoustic source term is displayed on the right and varies depending on the size of the velopharyngeal opening.
软腭咽瓣调节鼻腔和口腔之间的开口。在发音时，如果软腭不能完全闭合，会导致气流和/或声音不适当的漏入鼻腔，从而产生异常的声音，并增加鼻音。本研究旨在使用大涡模拟方法，研究在产生摩擦音时，开口大小变化对声源机制的影响。模型的基线几何形状基于一个软腭开口较小的受试者的咽气道，同时维持一个摩擦音。通过系统地扩大或缩小开口（其他条件相同）来对模型进行修改。结果表明，鼻腔中的声能与软腭开口的大小直接相关，并且存在一个临界尺寸，在此尺寸下，鼻腔中 Lighthill 声学源的幅度最大。远场声能及其与声源机制的相关性也取决于软腭开口的大小。显示了正常摩擦音/s/发音时具有软腭开口的特定患者的几何形状（图左）。显示了 Lighthill 声学源项（图右），其大小取决于软腭开口的大小。
