Cocktail party environments require listeners to tune in to a target voice while ignoring surrounding speakers. This presents unique challenges for bilingual listeners who have familiarity with several languages. Our study recruited English-French bilinguals to listen to a male target speaking French or English, masked by two female voices speaking French, English or Tamil, or by speech-shaped noise, in a fully factorial design. Listeners struggled most with L1 maskers and least with foreign maskers. Critically, this finding held regardless of the target language (L1 or L2) challenging theories about the linguistic component of informational masking, which contrary to our results predicts stronger interference with greater target-to-masker similarity such as L2 vs L2 compared to L2 vs L1. Our findings suggest that the listener’s familiarity with the masker language is an important source of informational masking in multilingual environments.
