Voice undergoes its most pronounced developmental changes during adolescence, yet acoustic normative data for Korean middle and high school students, differentiated by grade and sex, remain limited, with existing norms based on adults or Western speak...
Voice undergoes its most pronounced developmental changes during adolescence, yet acoustic normative data for Korean middle and high school students, differentiated by grade and sex, remain limited, with existing norms based on adults or Western speakers. This study aimed to establish preliminary grade- and sex-specific acoustic norms for Korean adolescents by simultaneously applying the Multi-Dimensional Voice Program (MDVP), the Analysis of Dysphonia in Speech and Voice (ADSV), and Real-Time Pitch (RTP) to both sustained vowel phonation and connected speech.
Participants were Korean adolescents from the first year of middle school to the third year of high school (grades 7–12, ages 13–18). The final analysis included 212 speakers (117 male, 95 female) for the sustained vowel /a/ and 217 (107 male, 110 female) for connected speech. F0, F0 SD, vF0, jitter, shimmer, and NHR were obtained with MDVP; CPP, L/H ratio, and CSID with ADSV (both tasks); and mean speaking fundamental frequency (SFF) and vocal intensity (Energy) with RTP. Vocal intensity, however, is sensitive to recording conditions and was analyzed only as an exploratory relative measure. Grade and sex effects were examined using two-way (grade × sex) ANOVA followed by sex-separated tests, together with cross-task correlations and descriptive normative data (means, standard deviations, and percentiles).
The sex main effect was largest in pitch-related measures, with sex explaining approximately 80% of the variance in both F0 (ηp² = .818) and mean speaking fundamental frequency (SFF; ηp² = .820). Grade-related changes in pitch were observed primarily among male adolescents: F0 decreased markedly from grades 7 to 9 and remained relatively stable thereafter. In contrast, the mean-normalized coefficient of variation of F0 (vF0) did not differ significantly across grades, indicating that the stabilization reflected an absolute decline in F0 rather than a change in relative pitch variability. Jitter, shimmer, and NHR showed no consistent grade-related differences but differed significantly by sex. Several voice quality measures did vary by grade: in male adolescents, CPP and CSID changed approximately one grade later than pitch-related measures, and in female adolescents, the vowel L/H ratio showed the most marked grade effect (η² = .297). Pitch measures showed excellent agreement across the sustained vowel and connected speech tasks (r ≈ .95), whereas quality measures exhibited task-dependent variability.
These grade- and sex-specific norms, derived from multiple acoustic indicators, provide foundational reference data for the screening and clinical assessment of adolescent voice disorders and puberphonia, and support the use of sex-specific normative values. As a preliminary study validating the measurement procedures, it indicates that definitive norms will require larger-scale, longitudinal investigations that incorporate indices of pubertal maturation and focus on developmentally sensitive acoustic measures (F0, SFF, CPP, and L/H ratio).