Speaker-specific formant dynamics: An experiment on Australian English /aI/

Abstract

Formant frequency dynamics are relevant to forensic speaker identification since they are determined by the shape and size of a speaker’s vocal tract and the way he or she configures the articulators for speech. This study investigates individual|differences in the formant dynamics of /aI/ produced by five male Australian English speakers, and the effects of changes in speaking rate and prosodic stress on these differences. F1, F2 and F3 frequencies are examined at equidistant time-normalized intervals through /aI/. At each measurement point a degree of speaker individuality is present, and speaker differentiation improves as increasing numbers of measurement points are considered in combination. Patterns of speaker-specific behaviour are generally consistent across different rate-stress conditions. Discriminant analyses based on predictors from all three formants yield classification rates of 88–95%, with nuclear-stressed /aI/ performing best. The findings suggest that further research to develop techniques for characterizing individual speakers using formant dynamics is warranted.