Age and gender variability and preliminary reference data for acoustic and cepstral voice measures in Turkish adults

Abstract Acoustic voice analysis is widely used in clinical voice assessment; however, interpretation of acoustic measures requires consideration of demographic and methodological variability. Reference datasets based on open-source tools remain limited for Turkish-speaking adults. This study aimed to investigate age- and gender-related variability in acoustic voice parameters using Praat and to provide preliminary reference values for clinical interpretation. A cross-sectional study was conducted with 121 normophonic Turkish-speaking adults aged 18–70 years. Participants completed sustained vowel phonation and continuous speech tasks. Acoustic analysis included fundamental frequency, jitter, shimmer, harmonic-to-noise ratio, smoothed cepstral peak prominence, and Acoustic Voice Quality Index version 02.06. Significant gender differences were observed for fundamental frequency, shimmer local, harmonic-to-noise ratio, smoothed cepstral peak prominence, and the Acoustic Voice Quality Index. Age-related main effects on shimmer local, shimmer APQ3 and the Acoustic Voice Quality Index were nominally significant but did not survive correction for multiple comparisons and are therefore reported as exploratory. Furthermore, there were significant interactions between gender and age for fundamental frequency and smoothed cepstral peak prominence in sustained vowel phonation. Unadjusted sex comparisons, age-adjusted effects and sex by age interactions are reported separately throughout. Sex-specific preliminary reference intervals (2.5th to 97.5th percentiles) are reported. These findings highlight the importance of age-, gender-, and software-specific reference values in acoustic voice analysis. The study provides Praat-based preliminary reference data that could support more accurate and context-specific interpretation of acoustic voice analysis and future research on voice disorders in Turkish-speaking groups.