Changes in voice quality and voice function of performing artists during the educational process: 1st and 4th grade sample

This study aimed to investigate the changes in voice quality and vocal functions associated with the educational process in first- and fourth-year students enrolled in opera and theatre departments. A total of 132 students from conservatories across Türkiye participated in the study. To evaluate participants' subjective experiences related to voice use, the Turkish Singing Voice Handicap Index-10 (T-SVHI-10), the Voice Fatigue Index (VFI), the Glottal Function Index (GFI), and the Reflux Symptom Index (RSI) were administered. Aerodynamic and acoustic features were examined through maximum phonation time (MPT) for /a/ and /i/, s/z ratio, fundamental frequency (F0), jitter (local, PPQ5), shimmer (local, APQ11), and noise-to-harmonics ratio (NHR). Among opera students, fourth-year participants demonstrated longer /a/ and /i/ MPT values and markedly lower jitter and shimmer scores, indicating improvements in frequency and amplitude stability with advanced training. In the theatre group, fourth-year students also showed increased MPT values, while no significant differences were observed in s/z ratio or F0. NHR values were lower in fourth-year students in both departments compared to first-year students. Regarding subjective measures, the effect of class level on T-SVHI-10, VFI, and GFI scores was limited in opera students, whereas theatre students in the first year exhibited stronger associations among vocal fatigue, reflux symptoms, and glottal function. Overall, the findings suggest that professional voice training provides notable enhancements in acoustic parameters, while changes in perceived vocal handicap vary according to department and educational level. Keywords: opera students, theatre students, acoustic analysis, vocal function, voice training.