Changes in acoustic characteristics of the voice across the life span: measures from individuals 4-93 years of age.

PURPOSE The purpose of the present investigation was to examine acoustic voice changes across the life span. Previous voice production investigations used small numbers of participants, had limited age ranges, and produced contradictory results. METHOD Voice recordings were made from 192 male and female participants 4-93 years of age. Acoustic measures of fundamental frequency (F0), sound pressure level (SPL), and signal-to-noise ratio (SNR) were made. Coefficients of variation for F0, SPL, and SNR served as measures of variability. Variables were analyzed separately with stepwise regressions, using age and sex as predictors. RESULTS Differences in F0 and SNR across the life span were sex specific. Male and female participants demonstrated significant nonlinear trends for F0, but the trends were stronger for male participants. Female participants demonstrated a similar nonlinear trend for SNR, whereas male participants demonstrated linear increases in SNR with age. Variability of F0, SPL, and SNR followed nonlinear trends, higher at younger and older ages. CONCLUSIONS Changes in voice production occur throughout the life span, often in a nonlinear way and differently for male and female individuals. Higher variability of acoustic measures of voice in both young and old speakers reflects changes in anatomic structure, physiologic mechanisms, and motor control.