Receptive vocabulary predicts multilinguals' recognition skills in adverse listening conditions.

Adverse listening conditions are known to affect bilingual listeners' intelligibility scores more than those of monolingual listeners. To advance theoretical understanding of the mechanisms underpinning bilinguals' challenges in adverse listening conditions, vocabulary size and language entropy are compared as predictors in a sentence transcription task with a heterogeneous multilingual population representative of a speech community. Adverse listening was induced through noise type, bandwidth manipulations, and sentences varying in their semantic predictability. Overall, the results generally confirm anticipated patterns with respect to sentence type, noise masking, and bandwidth. Listeners show better comprehension of semantically coherent utterances without masking and with a full spectrum. Crucially, listeners with larger receptive vocabularies and lower language entropy, a measure of the predictability of one's language use, showed improved performance in adverse listening conditions. Vocabulary size had a substantially larger effect size, indicating that vocabulary size has more impact on performance in adverse listening conditions than bilingual language use. These results suggest that the mechanism behind the bilingual disadvantage in adverse listening conditions may be rooted in bilinguals' smaller language-specific receptive vocabularies, offering a harmonious explanation for challenges in adverse listening conditions experienced by monolinguals and multilinguals.