The shaky voice of aging localized to the larynx: dissociation of frequency and amplitude tremor

Aging is associated with structural and functional changes of the vocal folds that may result in presbyphonia, often perceived as a weak or shaky voice. However, the quantitative characterization of underlying age-related vocal tremor across the adult lifespan remains limited. This cross-sectional study investigated the characteristics of vocal tremor across the adult lifespan using automated acoustic analysis. A total of 291 native speakers aged 18-94 years were recruited and underwent perceptual voice evaluation and acoustic analysis during sustained phonation of the vowel /a/. Vocal tremor was quantified using digital signal processing, focusing on the prominence of fundamental frequency tremor (PF0T) and the prominence of amplitude tremor (PAT). A moderate-to-strong positive correlation between age and PF0T was observed in both males and females, indicating increasing instability of fundamental frequency with advancing age. In contrast, PAT did not show a significant age-related increase after correction for multiple comparisons. Perceptual ratings of tremor demonstrated only weak correlations with age but were moderately associated with acoustic measures of tremor. Normative models revealed that physiological tremor in healthy aging remains well below pathological thresholds reported in neurological disorders. These findings indicate that age-related vocal tremor is characterized predominantly by increasing instability of fundamental frequency rather than amplitude modulation, localizing the dominant age effect to laryngeal control of vocal fold tension rather than to respiratory drive. Automated acoustic analysis provides a sensitive and objective method for detecting subtle age-related vocal changes and may support future biomarker development for distinguishing physiological from pathological vocal tremor.