In this study, we investigated crosslinguistic influence in the phonetic systems of simultaneous bilinguals (2L1s) during adulthood.

Specifically, we analyzed the voice onset time (VOT) of the voiceless stop /k/ in the spontaneous speech of 14 German–French bilinguals who grew up in France or Germany. We looked at both languages, first comparing the groups, second comparing their VOT to their global accent.

The material consisted of interviews, lasting for about half an hour.

Most 2L1s showed distinct VOT-ranges in their two languages, even if they were perceived to have a foreign accent in the minority language of their childhood environment. We conclude that the phonetic systems of 2L1s remain separate and stable throughout the lifespan. However, the 2L1s from France had significantly shorter VOTs in German than the 2L1s from Germany, and their speech was overall more accented. These findings are discussed with respect to the role of intra- and extra-linguistic factors.

Our study adds a new perspective to existing VOT studies of bilinguals by using naturalistic speech data and by comparing two groups of 2L1s who have the same language combination but grew up in different countries, which allows us to evaluate the impact of their childhood environment on VOT development.

Language exposure during childhood seems to be beneficial for pronunciation during adulthood.