This longitudinal production study tracks the changes in formant values for the vowels of L2 and L3. The study was conducted on a group of 14 Polish adolescent multilinguals and shows that L3 vowels changed in quality over the first year of acquisition, while the L2 vowels remained the same.
Research on multilingual phonological acquisition has shown that Cross-Linguistic Influence (CLI) plays a role not only in forming the newly acquired language (e.g. Gut 2010, Wrembel 2015) but also in reshaping the previously established systems (Cabrelli 2017). Although some earlier studies have investigated vowel quality in the third language (L3) (e.g. Missaglia 2010, SypiaÅ„ska 2016, KopeÄ
