Abstract Speech‐in‐noise perception is consistently reported to be impaired in learning disorders, which stresses the importance of documenting its developmental course in young children. In this cross‐sectional study, ninety children (41 females, 5.5–11.6 years old) and nineteen normal‐hearing adults (15 females, 20–30 years old) were tested with a newly developed closed‐set speech perception in babble‐noise test, combining two levels of phonological difficulty and two noise levels. Results showed that speech‐in‐babble‐noise perception takes a definite maturation step around 7 years of age ( d = 1.17, grade effect) and is not mature at 10 years of age when compared to young adults ( d = 0.94, group effect). Developmental trajectories of both accuracy and response times were evaluated, with influences of psycholinguistic factors, to foster the development of adequate screening tests.