The aim of this study was to analyze children's graphical notations as external representations of their experiencing when listening to simple sonic stimuli and complex musical fragments. More specifically, we assessed the impact of four factors on children's notations: age, musical background, complexity of the fragment, and most salient sonic/musical parameter. One hundred and sixteen children--8-9-year-olds and 11-12-year-olds with and without extra music education--were exposed to six fragments that differed from one another in terms of complexity and the most salient sonic parameter. Their notations were categorized by means of a classification scheme that differentiated between (a) global notations, which represent the fragments in a holistic way, and (b) differentiated notations, which try to capture one or more sonic/musical parameters in their temporal unfolding. As expected, we found a significant impact of age and music education, with older children and children with extracurricular music education generating more differentiated notations. Furthermore, complex sounding fragments elicited much fewer differentiated notations than simple ones. We also found significant interaction effects between subject and task variables. Finally, we found a correlation between the sophistication level of children's representations of the simple and complex fragments. (Contains 10 tables, 10 figures and 4 notes.)