Parameterization of vocal tract area functions by empirical orthogonal modes
Parameterization of vocal tract area functions by empirical orthogonal modes
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DOI：
10.1006/jpho.1998.0076
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发表时间：
1998-07-01
影响因子：
1.9
通讯作者：
Titze, IR
中科院分区：
文献类型：
--
作者：
Story, BH;Titze, IR
一组10个元音面积函数，MRI测量的基础上，已被参数化的“经验正交模式分解”，准确地表示每个面积函数的平均面积函数和一系列的正交基函数的比例量的总和。发现平均面积函数具有类似于均匀管的共振峰结构（即，几乎相等间隔的共振峰），这表明经验正交模式是对平均（类似于中性）元音形状的扰动，非常像过去的声道分析已经考虑了对均匀管的扰动。两个最重要的经验正交模式的声学特性进行了检查，表明这两种模式往往增加第一共振峰的模态振幅系数都从负值增加到正值。然而，发现第二共振峰的频率随着第一模态系数的值的增加而减小，并且随着第二模态系数的值的增加而增加。接下来，提出了F1-F2共振峰对和声道面积函数之间的映射，该映射在很大程度上是一对一的，但最初受到恒定声道长度的限制。给出了一种在映射中包含可变声道长度和高阶正交模的可能方法。模-共振峰映射提出了从语音波形确定生理上真实的面积函数的逆映射的可能性，并给出了一个简单的例子。最后，经验正交模式的10个元音和8个辅音的集合推导出，并显示出许多相似之处，只有元音的情况下。(C)北京：科学出版社.
A set of ten vowel area functions, based on MRI measurements, has been parameterized by an "empirical orthogonal mode decomposition" which accurately represents each area function as the sum of the mean area function and proportional amounts of a series of orthogonal basis functions. The mean area function was found to possess a formant structure similar to that of a uniform tube (i.e., nearly equally spaced formants) suggesting that empirical orthogonal modes are perturbations on the mean (similar to neutral) vowel shape much like past vocal tract analyses have considered perturbations on a uniform tube. The acoustic characteristics of the two most significant empirical orthogonal modes were examined, showing that both modes tend to increase the first formant as the modal amplitude coefficients are both increased from negative to positive values. However, the second formant was found to decrease in frequency for increasing values of the first modal coefficient and to increase for increasing values of the second mode coefficient. Next, a mapping between F1-F2 formant pairs and vocal tract area functions is proposed which is largely one-to-one but was initially limited by a constant vocal tract length. A possible method to include variable vocal tract length and higher ordered orthogonal modes in the mapping is given, The mode-to-formant mapping suggested the possibility of an inverse mapping to determine physiologically realistic area functions from a speech waveform and a simple example is presented. Finally, empirical orthogonal modes for a collection of ten vowels and eight consonants were derived and showed many similarities to those for the vowel-only case. (C) 1998 Academic Press.