本文以我国西南地区少数民族语言侗语为例,研究言语产生过程中元音和声调之间的相互影响。研究采用的参数有基频、第一共振峰和第二共振峰以及通过超声成像设备测量获得的舌面最高点。研究结果表明,元音的固有基频(Intrinsic Fundamental Frequency,IF0)在不同的声调中有所不同,男声和女声也表现出差异。女声中平调的固有基频显著高于低平调,高平调没有出现固有基频;男声的高平调固有基频略高于中平调,低平调没有固有基频。这一结论与固有基频随着基频高低呈梯度变化的假设不符。声调的高低对元音/a/的第一共振峰有显著影响。通过本研究,我们推测元音固有基频是元音产生过程中调音器官和发声器官耦合的结果。同时,我们发现超声设备不适合被用于观测这种由于发声和调音的耦合引起的舌面高低的微小变化。
Conventional acoustic-to-articulatory inversion methods usually train the mapping model by using maximum likelihood or least square criterion,which assumes all the articulatory channels are equally important.In this paper,the importance of each articulatory channel at each time instant is modeled as an exponential function of its velocity profile and incorporated into the conventional least square loss function.The loss function is applied to optimize a batch-normalized Deep Neural Network(DNN).The result shows that the DNN trained with proposed cost function outperforms the one trained with traditional cost function.
