Measuring language proficiency in bilingual children using EEG-based neural tracking of continuous speech

Assessing language proficiency in bilingual children is challenging due to linguistic variability and limitations of behavioral language tests. EEG-based neural envelope tracking, which measures neural responses time-locked to the speech envelope during listening, might be a potential future complementary method. However, the relation between neural envelope tracking and language proficiency remains unclear. Therefore, we aim to investigate the relation between neural envelope tracking and language proficiency in children with varying levels of proficiency.

We determined neural envelope tracking of fifteen monolingual Dutch-speaking and fifteen bilingual Dutch-French-speaking children aged 6 to 8 years while they listened to continuous speech fragments in Dutch, French, and Italian. All participants comprehended the Dutch stories, only the bilingual children understood the French stories, and none of the children comprehended the Italian stories. A parental questionnaire and standardized language tests in Dutch and French provided behavioral language assessments, allowing for comparison with EEG-based tracking.

Group differences in neural tracking accuracy revealed higher tracking in comprehensible languages compared to incomprehensible ones, in both monolingual (Dutch > French = Italian) and bilingual children (Dutch = French > Italian). However, no significant correlations were found between neural envelope tracking and behavioral measurements.

Neural envelope tracking may offer a method to assess language comprehension in children as it distinguishes comprehensible from incomprehensible languages. However, further validation is needed to enhance its sensitivity to individual differences, as neural envelope tracking currently does not reflect children's language proficiency across different languages.