Can L2-English influence L1-German? The case of post-vocalic /r/

•We examine bi-directional transfer phenomena in second language acquisition.•We investigate the realisation of post-vocalic /r/ in varieties of L1/L2 English and L1 German.•L2 learners acquire regional characteristics of L2 varieties.•L2 phenomena shape L1 sound systems in sequential L2 acquisition.•We adopt a usage-based approach to second language acquisition.

This paper reports findings of an experiment investigating the vocalisation and the realisation of post-vocalic /r/ in varieties of English and German. The study aims to explore whether there are differences in the realisation of post-vocalic /r/ produced by native speakers of a German non-rhotic variety spoken in Berlin as a result of long-term exposure to a rhotic and a non-rhotic variety of English spoken in Belfast and Oxford. Rhotic and non-rhotic varieties of English and German differ in the realisation of constrictive and non-constrictive post-vocalic /r/.The results of an auditory and acoustic analysis of post-vocalic /r/ in the speakers' first language (L1) German and second language (L2) English suggest that exposure to a rhotic variety of English results in the realisation of a constrictive post-vocalic /r/ in their non-rhotic native language, German. However, this effect cannot be generalised since it varies according to the phonetic contexts of post-vocalic /r/. A usage-based approach can explain this variation by taking into account actual creative language use and communicative events, as well as cognitive aspects of language development.