Tracing the mechanisms that generate tonal content in voiced speech

嗓音障碍具有很高的社会和经济意义，因为它影响到我们社会的许多人。因此，患者的生理和心理压力增加，生活质量下降。健康人的正常声音是复杂的流体-结构-声学相互作用的结果。声带的结构性运动强烈地调节了流过声门的流动，声门产生了声音的主要部分。因此，正常健康的发音是以强烈的和声含量为特征的。声带折叠下游的声道是声学后向耦合对声带运动和流动的一个关键因素。因此，除了产生共振峰之外，我们假设声道也会影响产生的声音信号中高次谐波的产生，这对健康的声音至关重要。该研究项目的中心目标是在完全耦合的潜在机制的实验研究的基础上，促进对发声过程中音调声音产生的理解。我们实验室的实验装置在一个公认的喉部模型中复制了完全耦合的发声过程。我们的目标是通过集成几何变量简化的声道以及基于MRI的声道形状来进一步扩展其功能。这使我们能够单独研究发声过程中受声道影响的不同机制。该项目包含三个创新方面。(1)在完全耦合的实验方法中，将重点放在谐波含量和声学后耦合上，该实验方法代表了发声过程的基本机制。(2)使用我们最先进的基于PIV的技术，可以直接实验确定声源场和声辐射。(3)通过激光测振仪的测量，对声带的运动及其结构相互作用进行了全面的描述，并着重研究了声带中的谐波成分，最终得出了与声道后向耦合相互作用的谐音产生机制。

Voice disorders are of high social and economic relevance as it affects many people in our society. Consequently, concerned patients suffer from increased physiological and psychological stress as reduced quality of life.The normal voice of a healthy human is the result of a complex fluid-structure-acoustic interaction. The structural motion of the vocal folds intensely modulates the flow through the glottis, which generates the main portion of the sound. Thereby, normal and healthy phonation is characterized by a strong harmonic content. The vocal tract downstream of the vocal folds is a key factor for acoustic back-coupling on the vocal fold motion as well as the flow. Hence, in addition to creating formants, we hypothesize that the vocal tract also impacts the generation of higher harmonics in the resulting voice signal, which is crucial for a healthy voice. The central objective of the research project is to advance the understanding of tonal sound generation during phonation based on a fully-coupled experimental investigation of the underlying mechanisms. The experimental setup in our laboratory replicates the fully-coupled phonation process in a well-established larynx model. We aim to further extend its functionality by integrating geometry-variable simplified channels as well as an MRI-based vocal tract shape for experiments. This enables us to separately investigate the different mechanisms during phonation as influenced by a vocal tract. The project incorporates three innovative aspects. (1) The focus is set on the harmonic content and acoustic back-coupling in a fully-coupled experimental approach that represents the basic mechanisms of the phonatory process. (2) With our state-of-the-art PIV-based technique, a direct experimental determination of the acoustic source field and sound radiation is enabled. (3) A comprehensive description of the vocal fold motion and its structure interaction is generated by laser vibrometer measurements with a strong focus on its harmonic content, as well.Finally, this yields the mechanisms responsible for harmonic sound generation, which interacts with back-coupling of the vocal tract.