Lyapunov系数在嗓音障碍评估中的意义

The Clinical Significance of Calculating the Coefficients of Lyapunov in the Objective Assessment of Dysphonia

目的探讨Lyapunov系数在嗓音障碍客观分析中的意义,完善嗓音障碍的客观测试方法。方法声音样本采自132例嗓音障碍患者和47例嗓音正常者。采用法国开发的“EVA”嗓音工作站,选择2秒平稳段长元音/α/声信号作为分析样本,测试基频微扰(jitter)和计算Lyapunov系数。主观听感知评估采用日本言语音声学会制定的嗓音障碍评估系统GRBAS中的总嘶哑度(grade,G),4级评估标准。结果Lyapunov系数在不同的嗓音障碍分级组间均有统计学差异,jitter只在中度和重度嗓音障碍组间有统计学差异;Lyapunov系数与听感知评估结果的一致性达到46%,jitter的一致性为36%。回归分析结果显示,Lyapunov系数和jitter之间既有相关性,但又有不同(r2=0.582,P<0.001)。结论Lyapunov系数对嗓音障碍的测试优于jitter;非线性动态系统(相位图)的引入,为嗓音的客观分析开辟了新的研究领域。

Objective Measurement of the vibration instability by means of jitter in cases of dysphonia fails to take into account certain features of the vocal signal, such as modulation or bitonatily. These abnormalities appear in jitter measurements as instability （to give ＂true＂ instability）. The authors suggest the use of the coefficient of Lyapunov, a measurement which is used for non - linear dynamics. Our work had for objective to investigate the clinical significance of calculating the coefficients of Lyapunov in the objective assessment of dysphonia. Methods The vocal product of 47 normal and 132 dysphonie subjects was analyzed. The coefficient of Lyapunov and the jitter were measured during the stable period of a sustained/α：/vowel. For the coefficient of Lyapunov the authors used the algorythm which had been published previously. The measurements were compared with the perceptive analysis of the reading voice by a panel and divided into four grade （G0 to G3）. Results The coefficient of Lyapunov appeared to be more relevant than the jitter in distinguishing the various perceived grades. Precise recognition of the grade was obtained in 46% using the coefficient of Lyapunov as against only 36% using jitter. Conclusion The coefficient of Lyapunov is more relevant than the jitter by report has the perceptive analysis. The addition of this new index to the existing puriparametric methods of voice analysis seems to be promising.