Nonlinear dynamic analysis of voice in teachers with dysphonia

Nonlinear dynamic analysis identifies and describe the presence of ‘‘rules’’ underlying the seemingly random nature of a severely perturbed voice. Using this technique, the perturbed voice signal may be viewed as ‘‘chaotic’’ in nature rather than randomly perturbed. Nonlinear dynamic analyses of human voices have established the existence of chaos in human voice production. However, very few studies have characterised the voice in teachers with dysphonia using this method. The aim of the present study was to investigate voice characteristics in teachers with dysphonia using Nonlinear Dynamic Analysis methods. 28 teachers and age matched controls in the age range of 20-40 years served as subjects. The voice samples were recorded and a total of 15 Correlation Dimensions were obtained for the two groups. Results showed significant differences in the correlation dimensions between the two groups indicating a complexity in the laryngeal mechanism of teachers. Thus, it was concluded that Non linear dynamic analysis of voice provided a quantifiable data to assess dysphonia in teachers.