From classrooms to playgrounds, children's communication occurs in noisy environments. Although their peripheral auditory systems reach maturity approximately six months after birth, children experience persistent difficulties in perceiving speech in noise. When faced with noisy environments, listeners perform auditory scene analysis, allowing them to selectively focus on the relevant auditory target while ignoring interfering sounds. Stream segregation, a fundamental mechanism of scene analysis, involves organizing similar sound waves into a coherent stream, while distinguishing dissimilar acoustic components and attributing them to distinct sources. Two event-related potential components have been identified as 'neural signatures' of stream segregation: the Object-Related Negativity (ORN) and the P400.

Our study aims to examine (i) the maturation of neural correlates of stream segregation (ORN/P400) from childhood to adulthood and (ii) the development of the relationship between these neural correlates and speech perception in noise. Participants aged 8 to 23 years (children n=27, adolescents n=29, and adults n=27) were included in the study. ORN/P400 were recorded while participants performed an active stream segregation task. Participants also performed speech identification in noise tasks (behaviourally). Behavioral results indicate an improvement in both stream segregation and speech perception in noise from childhood to adulthood. Furthermore, stream segregation performance predicts speech perception in noise. Our neurophysiological findings suggest a reduction in amplitude of both ORN and P400 from childhood to adulthood, and P400 amplitude is a predictor of stream segregation performance.

Overall, our results suggest that the neural mechanisms underlying stream segregation follow a prolonged maturation trajectory, and support the progressive maturation of auditory scene analysis and speech perception in noise.