This chapter considers how longitudinal changes of a sociophonetic nature can be distinguished acoustically from changes due to biological aging of the vocal tract. The sociophonetic change is a reversion in later life to an accent that was produced in young adulthood. An American accent colored his vowels, but he showed evidence of change toward the Received Pronunciation (RP) accent in later life that assumed his accent prior to emigration. The focus of the analysis is on longitudinal data from Alistair Cooke and two female speakers: Queen Elizabeth II and Dagmar Berghoff, a German newsreader and trained actress. For all three speakers, the selected materials from public broadcasting archives that allowed to control for constant speech genres within the speakers. The model of age-related changes to F1 in Reubold and Harrington predicts that F1 should track a physiologically induced change of f0 especially when f0 and F1 are close together in frequency.