Relation of selected acoustical parameters and perceptual ratings to voice quality of Down syndrome children.

Judges using the Wilson Voice Profile rated the voice quality of 14 noninstitutionalized, 7- to 10-year-old Down syndrome children and a group of nonretarded children. The Down syndrome children received ratings different from the nonretarded children on the Severity subscale of the Wilson Voice Profile. Voice samples were analyzed acoustically in terms of fundamental frequency, fundamental frequency range, frequency and amplitude perturbations, and spectral noise-to-harmonic component ratios. Frequency perturbations, amplitude perturbations, and spectral noise-to-harmonic component ratios were significantly greater for the Down syndrome children. There were also significant correlations between judges' Severity ratings and frequency perturbation levels, amplitude perturbations levels, and spectral noise-to-harmonic component ratios.