Induced asymmetries in an excised larynx model: Impact of mucus characteristics on dynamics and acoustics

嗓音障碍不仅仅是由于声带的解剖组织变化引起的。发声过程是气流、喉组织结构、粘膜表层(即粘液)和由此产生的声学结果之间的复杂相互作用。这种流体-结构-声学相互作用的功能可能会被动力学行为中的左右不对称和振荡过程中声带的不充分闭合所干扰，即发声过程被干扰，语音质量降低。这个项目基于这样的假设，发声的贡献因素之间的耦合高度依赖并受到覆盖声带的粘液层的影响，粘液层代表气流和组织之间的自然边界层。到目前为止，这种相互关系在语音研究中一直被忽视。识别和量化粘液的动力学和声学补偿机制对于指导非侵入性治疗的嗓音质量是非常必要的。本项目的中心目标是调查喉部粘液及其在发声过程的因果链中的作用。因此，合成的粘液将在天然人类粘液样本范围内产生具有特征粘弹性特性的粘液。合成粘液样品对发声过程的影响将在前一个项目阶段开发的计算机控制实验装置中进行测试。这种设置允许可变地调整喉边界条件(例如，诱导的不对称和声门间隙)和同时的多模式测量(例如，高速视频内窥镜、流量、声门下压力、声学信号)。这将允许对所有的影响因素进行彻底的量化，并揭示发音中的因果关系。体外研究将使用从当地屠宰场收到的切除的猪喉进行。

Voice disorders do not only result from anatomical tissue alterations in the vocal folds. The phonation process is a complex interaction between airflow, laryngeal tissue structures, mucosal surface layer (i.e. mucus) and the resulting acoustic outcome. The functionality of this fluid-structure-acoustic interaction can be disturbed by left-right asymmetries in the dynamical behavior and insufficient closure of the vocal folds during oscillation; i.e. the phonation process is disturbed and the voice quality is reduced. This project is based on the hypothesis that the coupling between the contributory factors of phonation is highly dependent and influenced by the mucus layer that covers the vocal folds and represents the natural boundary layer between airflow and tissue. Up to date, this interrelation has been neglected in phonation studies. The identification and quantification of a compensatory mechanism of mucus on dynamics and hence the acoustics would be highly desirable in guiding voice quality for non-invasive treatment.The central objective of this project is the investigation of laryngeal mucus and its role in the cause-and-effect chain of the phonation process. Hence, synthetic mucus will be created with characteristic viscoelastic properties in the range of natural human mucus samples. The influence of the synthetic mucus samples towards the phonation process will be tested in the computer controlled experimental setup which was developed in the previous project phase. This setup enables variable adjustment of the laryngeal boundary conditions (i.e. induced asymmetry and glottal gap) and simultaneous multimodal measurements (i.e. high-speed videoendoscopy, flow, subglottal pressure, acoustic signal). This will allow a thorough quantification of all the contributing factors and reveal the causal interrelations in phonation. The ex vivo studies will be performed using excised porcine larynges received from the local slaughterhouse.