常见构音障碍元音病理声学特征研究

Acoustic Features of Vowels in Patients with Dysarthria

构音障碍是由于神经病变及言语产生有关的肌肉麻痹、收缩力减弱或运动不协调所致的言语障碍。目前国内对于此类言语障碍的研究多限发音层面,临床诊断和疗效的评价多采用主观感知和量表评估,而涉及实验室方法如声学分析的评估与研究鲜见。本文从计算机辅助测量构音障碍元音病理声学特征的角度,探讨其与疾病神经病理学的联系,其中涉及共振峰频率值、元音空间面积、共振峰集中率、元音持续时间、元音清晰度指数、基频微扰值、振幅微扰值、规范化噪声能量、基频标准差、元音离散度、椭圆范围、元音重叠度、元音三角面积、声学距离等声学指标。构音障碍器官运动模式的改变导致发音的不清晰和听理解性的下降,通过计算机线性预测反滤波技术提取声学参数,从客观层面分析构音障碍病理语音,帮助医师和治疗师发现患者声学特征方面与正常人对比存在的言语病理差异,了解内在机制。研究发现构音障碍患者元音的声学特征的某些方面与健康成人比较具有特异性,构音障碍患者元音共振峰表现出集中趋势压缩,频率的偏移与不准确(其频率与振幅的变化高于对照组),元音空间及元音清晰度指数均显著减小,且元音空间的大小与说话者的可懂度呈正相关。此外,元音离散程度与重叠范围可提示语音障碍程度。与此同时,构音障碍的元音时长会比正常对照组延长。这些异常表现,显示出构音障碍患者发音运动存在着不精确性和异常运动。这些病理语音特征的发现有助于通过客观化的方法有效评估临床构音障碍,并指导精准言语康复训练。

Dysarthria are speech disorders that result from neurologic impairments associated with weakness,slowness,or incoordination of the musculature used to produce speech.Domestic studies on this speech disorder are mostly limited to acupuncture,electrical stimulation and other therapeutic effects,and the evaluation of the therapeutic effect is mostly subjective,involving the lack of acoustic analysis.In this paper,the acoustic features of vowels with dysarthria were analyzed,such as resonant frequency,vowel space area,formant centralization ratio,vowel duration,vowel articulation index,jitter,shimmer,normalizednoise energy,standard deviation of F0,vowel dispersion,vowel overlap,vowel triangle area,acoustic distance and so on.In dysarthria,movement patterns change of articulators lead to obscure pronunciation and decline of the listening comprehension.Doctors and therapists can find the pathology differences of acoustic features between patients and normal speech and understand the internal mechanism through extracting acoustic parameters with the technique of linear predictive coding with computer.Some differences of the acoustic features of vowels with dysarthria were found compared with healthy adults.The vowel formant of the patients with dysarthria showed a centralized tendency,frequency deviation and inaccuracy(the change of frequency and amplitude was higher than that of the control group),vowel space area and vowel articulation index(VAI)were significantly reduced,and the size of vowel space was positively correlated with the speaker’s understandability.The degree of vowel dispersion and overlap can indicate the severity of speech disorders.Also,the duration of vowels was longer than that of the normal control group.These abnormalities show that there are inaccuracies and abnormal movements in articulation movement in patients with dysarthria.These found of the above the acoustic features of vowels with dysarthria are conducive to the effective evaluation of clinical dysarthria through objective methods and can direct the accurate training in speech rehabilitation.