Phonatory function of neurologically impaired patients.

Previous studies investigated the use of acoustic perturbation measures as a screening tool for neuropathologies with conflicting results. In the present study, five parameters of phonatory function (jitter, shimmer, signal-to-noise ratio, fundamental frequency, and standard deviation of fundamental frequency) were obtained from samples of sustained phonation in three neuropathological groups (Parkinson, Huntington, cerebellar ataxia) and a normal control group to assess the use of acoustic measures in differential diagnosis. In addition, perceptual judgements of the severity of dysphonia for each patient were obtained. The results indicated that perturbation measures of the neuropathological groups showed a higher degree of variability compared to normals. From the five parameters studied, only the standard deviation of fundamental frequency differentiated among neuropathological subgroups. The acoustic parameters studied did not clearly reflect the perceived dysphonia for all subgroups.