Chan Roger W, Titze Ingo R
Otolaryngology--Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9035, USA.
J Acoust Soc Am. 2006 Apr;119(4):2351-62. doi: 10.1121/1.2173516.
Analytical and computer simulation studies have shown that the acoustic impedance of the vocal tract as well as the viscoelastic properties of vocal fold tissues are critical for determining the dynamics and the energy transfer mechanism of vocal fold oscillation. In the present study, a linear, small-amplitude oscillation theory was revised by taking into account the propagation of a mucosal wave and the inertive reactance (inertance) of the supraglottal vocal tract as the major energy transfer mechanisms for flow-induced self-oscillation of the vocal fold. Specifically, analytical results predicted that phonation threshold pressure (Pth) increases with the viscous shear properties of the vocal fold, but decreases with vocal tract inertance. This theory was empirically tested using a physical model of the larynx, where biological materials (fat, hyaluronic acid, and fibronectin) were implanted into the vocal fold cover to investigate the effect of vocal fold tissue viscoelasticity on Pth. A uniform-tube supraglottal vocal tract was also introduced to examine the effect of vocal tract inertance on Pth. Results showed that Pth decreased with the inertive impedance of the vocal tract and increased with the viscous shear modulus (G") or dynamic viscosity (eta') of the vocal fold cover, consistent with theoretical predictions. These findings supported the potential biomechanical benefits of hyaluronic acid as a surgical bioimplant for repairing voice disorders involving the superficial layer of the lamina propria, such as scarring, sulcus vocalis, atrophy, and Reinke's edema.
分析和计算机模拟研究表明，声道的声阻抗以及声带组织的粘弹性特性对于确定声带振荡的动力学和能量传递机制至关重要。在本研究中，通过考虑黏膜波的传播以及声门上声道的惯性电抗（惯性）作为声带流动诱导自振荡的主要能量传递机制，对线性小振幅振荡理论进行了修正。具体而言，分析结果预测，发声阈值压力（Pth）随声带的粘性剪切特性增加而增加，但随声道惯性而降低。该理论使用喉部物理模型进行了实证检验，其中将生物材料（脂肪、透明质酸和纤连蛋白）植入声带覆盖层，以研究声带组织粘弹性对Pth的影响。还引入了均匀管声门上声道来检查声道惯性对Pth的影响。结果表明，Pth随声道的惯性阻抗降低而降低，并随声带覆盖层的粘性剪切模量（G"）或动态粘度（eta'）增加而增加，与理论预测一致。这些发现支持了透明质酸作为一种手术生物植入物在修复涉及固有层浅层的嗓音障碍（如瘢痕形成、声带沟、萎缩和Reinke水肿）方面的潜在生物力学益处。
