Beyond the average: embracing speaker individuality in the dynamic modeling of the acoustic-articulatory relationship

Abstract

This paper explores the acoustic-articulatory relationship while considering individual differences in speech production. We aimed to determine whether there is a causal relationship between tongue movements and the contours of the first and second formant frequencies (F 1 and F 2) employing a hierarchical Bayesian continuous-time dynamic model, which allows for a more direct connection between the acoustic and articulatory measured variables and theories involving dynamicity. The results show predictive tendencies for both formants, where the anteroposterior and vertical tongue movements may predict changes in F 1, with rising predicting an increase and retraction a decrease; and with tongue fronting and tongue height inversely predicting F 2. Further, the modeled individual differences showed similar global tendencies, except for the rate of change of F 2. Overall, this study provides valuable insights into the relationship between tongue articulatory variables and formant contours, while accounting for between-speaker variability. The results show predictive tendencies for both formants, where the anteroposterior and vertical tongue movements may predict changes in f1, with rising predicting an increase and retraction a decrease; and with tongue fronting and tongue height inversely predicting f2. Further, the modeled individual differences showed similar global tendencies, however with larger error estimates. Overall, this study provides valuable insights into the relationship between tongue articulatory variables and formant contours, while accounting for between-speaker variability.