Esta obra tem licença Creative Commons http://creativecommons.org/licenses/by/4.0 * Full Professor at Universidade Federal do Rio Grande do Sul (UFRGS), Department of Modern Languages, Brazil, and at Programa de Pós-Graduação em Letras (PPGLet-UFRGS) and Programa de pós-Graduação em Língua e Cultura (PPGLinC-UFBA). He received his doctorate in Language Studies from UFRGS in 2016. His research activities address phonetics and phonology in bilingual development. He is interested in how bilinguals alter their languages over their lifespan, the role of social factors in bilingual speech production, and the relationship between speech production and perception. His e-mail address is kupske@gmail.com. ORCID: 0000-0002-0616-612X.  ** Professor at Universidade de Brasília (UnB), Department of Linguistics, Portuguese and Classical Languages, Brazil, and at Programa de Pós-Graduação em Linguística of Universidade Federal do Ceará (PPGLin-UFC). He is a researcher at the National Council for Scientifc and Technological Development (CNPq-Brazil). He holds a PhD degree from Universidade de Brasília (2012). His research interests include phonological development and quantitative data analysis. E-mail address: ronaldo.junior@unb.br. ORCID: 0000-0002-8610-0306. *** Associate Professor at Universidade Federal do Rio Grande do Sul (UFRGS), Department of Modern Languages, Brazil, and Programa de Pós-Graduação em Letras (PPGLet-UFRGS). He is a researcher at the National Council for Scientifc and Technological Development (CNPq-Brazil). He holds a PhD degree from Pontifícia Universidade Católica do Rio Grande do Sul (2008). His research interests include phonetics/ phonology in bilingual/multilingual development. E-mail address: ukalves@gmail.com. ORCID: 0000-0001- 6694-8476. DOI: http://dx.doi.org/10.5007/2175-8026.2023.e94531 A COMPARISON BETWEEN FULL TIME EQUIVALENT AND LENGTH OF RESIDENCE AS MEASUREMENTS OF TIME IN BILINGUAL SPEECH RESEARCH: THE CASE OF FIRST LANGUAGE ATTRITION Felipe Flores Kupske 1* Ronaldo Mangueira Lima Jr. 1** 1 Universidade de Brasília, Brasília, DF, Brasil Ubiratã Kickhöfel Alves 2*** 2 Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil Abstract 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). Tis 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 efects. As a result, the models showed a positive efect of time on VOT values, with VOT values increasing over LOR. However, the models that used FTE yielded greater efects with greater credibility. We conclude that LOR underestimates the efect of time, making FTE a more accurate metric since it incorporates both ‘time’ and ‘language use’. Keywords: Full Time Equivalent; Length of Residence; First Language Attrition; Complex Dynamic Systems.