Consistency of Voice Frequency and Perturbation in Children.

Objective: 1) Evaluate normal pediatric voice frequency and perturbation measures with Voice Evaluation Suite (VES) and the Multi Dimensional Voice Program (MDVP). 2) Determine consistency of these measures over time. 3) Understand which measures might be most useful for evaluating children with voice disorders. Method: Prospective, longitudinal study of normal voices of 50 children aged 4 to 17 years. Two tests of sustained utterances from each child were evaluated by 2 computerized voice analysis programs for frequency and perturbation. Intraclass correlation coefficient (ICC) assessed the reliability between the samples. Results: Children (M:F 1.08:1) with a mean age of 8.34 years were tested on an average of 54.2 minutes apart. Each test included 4 utterances; 1 was analyzed by MDVP and 3 grouped utterances were averaged and evaluated by VES. Fundamental frequency had excellent reliability (ICC > 0.75) in both VES and MDVP. Jitter, shimmer, and noise to harmonic ratio were poorly reliable (ICC ≤ 0.4) in MDVP but had good reliability (ICC 0.4-0.75) in VES. Conclusion: Consistent measures of frequency can be derived from single, sustained utterances in children. Averaging multiple samples improves consistency of perturbation. Future work is needed to evaluate whether evaluating acoustic measure stability in spontaneous speech and in sustained utterances cued by tuning frequencies may provide further insight on pediatric voice consistency.