Noise-based acoustic features of Polish retroflex fricatives in children with normal pronunciation and speech disorder

•Acoustic analysis of articulation of Polish retroflex sibilants /ʂ, ʐ/ in children.•Normal and pathological (interdental/dental) productions by 42 preschool children.•Entire spectrum and frication noise features, including novel distinctive metrics.•Normal retroflex articulation is acoustically distinguishable from pathologies.•Features from different groups contribute to particular sibilant oppositions.