A comparison between Full Time Equivalent and Length of Residence as measurements of time in bilingual speech research: the case of first language attrition

Full Time Equivalent (FTE), a product of Length of Residence (LOR) in L2 contexts multiplied by an index of frequency of L2 use, has been considered to be an important factor in bilingual speech development (Flege & Bohn, 2021). This work, therefore, seeks to analyze changes in the Voice Onset Time (VOT) of Brazilian Portuguese-L1 (short lag) in contexts of English-L2 (long lag) as a function of LOR and FTE (N=44) through Bayesian linear regression models with mixed effects. As a result, the models showed a positive effect of time on VOT values, with VOT values increasing over LOR. However, the models that used FTE yielded greater effects with greater credibility. We conclude that LOR underestimates the effect of time, making FTE a more accurate metric since it incorporates both ‘time’ and ‘language use’.