Mammalian laryngseal air sacs add variability to the vocal tract impedance: Physical and computational modeling
Mammalian laryngseal air sacs add variability to the vocal tract impedance: Physical and computational modeling
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DOI：
10.1121/1.2924125
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发表时间：
2008-07-01
影响因子：
2.4
通讯作者：
Thomson, Scott L.
中科院分区：
文献类型：
--
作者：
Riede, Tobias;Tokuda, Isao T.;Thomson, Scott L.
从主要声道分支出来的腔在非人类中普遍存在。哺乳动物的气囊存在于人类的亲戚中，包括所有四种大猿，但只有一个大大减少的版本存在于人类中。本文着重研究气囊的声学功能。研究了气囊是否影响语音振幅和共振峰位置的假设。利用了一个多层合成模型的声带耦合声道模型。作为气囊模型，考虑了四种构型：开放和封闭的均匀管状侧支、刚性空腔和可充气空腔。结果表明，一些气囊配置可以提高声级。此外，气囊模型引入了一个或多个额外的共振频率，在一定程度上移动了主声道的共振峰，但不像以前建议的那样强烈。此外，发声的动态范围可以通过气囊来扩展。一个新的发现也是声道阻抗的可变性增加，导致强烈的非线性源-滤波器相互作用的影响。实验表明，气囊状结构可以使声源不稳定。通过传输线计算模型验证了计算结果。(C)2008年，美国声学学会。
Cavities branching off the main vocal tract are ubiquitous in nonhumans. Mammalian air sacs exist in human relatives, including all four great apes, but only a substantially reduced version exists in humans. The present paper focuses on acoustical functions of the air sacs. The hypotheses are investigated on whether the air sacs affect amplitude of utterances and/or position of formants. A multilayer synthetic model of the vocal folds coupled with a vocal tract model was utilized. As an air sac model, four configurations were considered: open and closed uniform tube-like side branches, a rigid cavity, and an inflatable cavity. Results suggest that some air sac configurations can enhance the sound level. Furthermore, an air sac model introduces one or more additional resonance frequencies, shifting formants of the main vocal tract to some extent but not as strongly as previously suggested. In addition, dynamic range of vocalization can be extended by the air sacs. A new finding is also an increased variability of the vocal tract impedance, leading to strong nonlinear source-filter interaction effects. The experiments demonstrated that air-sac-like structures can destabilize the sound source. The results were validated by a transmission line computational model. (C) 2008 Acoustical Society of America.