Kindersprache (pathol.) ; Child language (pathol.) ; Specific language impairment; SLI; Dysgrammatismus (Kindersprache) ; Dysgrammatism (child language) ; Handicapped language acquisition ; Pathologischer Spracherwerb (phon.) ; Phonological development (pathol.) ; Motor speech disorder; Sprachpathologie (phonet.) ; Language pathology (phonet.) ; Artikulation (pathol.) ; Articulation (pathol.) ; Case study (pathol.) ; Language intervention; Children (speech therapy with) ; Speech therapy for children ; Vowel system ; English