Sanguineti V, Laboissière R, Ostry D J
Dipartimento di Informatica, Sistemistica e Telematica, Università di Genova, Italy.
J Acoust Soc Am. 1998 Mar;103(3):1615-27. doi: 10.1121/1.421296.
A model of the midsagittal plane motion of the tongue, jaw, hyoid bone, and larynx is presented, based on the lambda version of equilibrium point hypothesis. The model includes muscle properties and realistic geometrical arrangement of muscles, modeled neural inputs and reflexes, and dynamics of soft tissue and bony structures. The focus is on the organization of control signals underlying vocal tract motions and on the dynamic behavior of articulators. A number of muscle synergies or "basic motions" of the system are identified. In particular, it is shown that systematic sources of variation in an x-ray data base of midsagittal vocal tract motions can be accounted for, at the muscle level, with six independent commands, each corresponding to a direction of articulator motion. There are two commands for the jaw (corresponding to sagittal plane jaw rotation and jaw protrusion), one command controlling larynx height, and three commands for the tongue (corresponding to forward and backward motion of the tongue body, arching and flattening of the tongue dorsum, and motion of the tongue tip). It is suggested that all movements of the system can be approximated as linear combinations of such basic motions. In other words, individual movements and sequences of movements can be accounted for by a simple additive control model. The dynamics of individual commands are also assessed. It is shown that the dynamic effects are not neglectable in speechlike movements because of the different dynamic behaviors of soft and bony structures.
基于平衡点假设的拉姆达版本，提出了一个关于舌头、下颌、舌骨和喉部矢状面中部运动的模型。该模型包括肌肉特性和肌肉的实际几何排列、模拟的神经输入和反射，以及软组织和骨结构的动力学。重点在于声道运动背后控制信号的组织以及发音器官的动态行为。识别出了该系统的一些肌肉协同作用或“基本运动”。特别地，研究表明，在肌肉层面，矢状面声道运动的X射线数据库中的系统变异源可以用六个独立指令来解释，每个指令对应发音器官运动的一个方向。有两个指令用于控制下颌（分别对应矢状面下颌旋转和下颌前突），一个指令控制喉部高度，还有三个指令用于控制舌头（分别对应舌体的前后运动、舌背的拱起和平展以及舌尖的运动）。研究认为，该系统的所有运动都可以近似为这些基本运动的线性组合。换句话说，个体运动和运动序列可以通过一个简单的加法控制模型来解释。还评估了各个指令的动力学。结果表明，由于软组织和骨结构的动态行为不同，在类似语音的运动中，动态效应不可忽略。
