Using sound and music as a metaphor to approach curricular mathematical contents in Primary Education seems an interesting field that deserves some research. Both music and sound can synergically act as scaffolding for learning, intervening as part of situated knowledge, and they could offer a new perspective for learning mathematics at schools, giving pupils opportunities to develop their own mental representations. Also, the incorporation of an affective/emotional analysis, as criteria for evaluation, seems pertinent and complementary to other criteria in the production of multimedia material with educational purposes both in formal and non-formal domains of education. These are the intentions of the present work, which shows the design, implementation and assessment of AudioFractions, as part of an educational software package called Sound Interactive Music- Mathematics, which was conceived to aid mathematical learning through sound and music in Chilean Primary Education. The investigation was carried out in a three-stage design: 1) generate significant metaphors; 2) implement and test functional software prototypes and didactic guidelines; and 3) assess the software. Pupils in risk of social exclusion at three priority public schools in Santiago de Chile (N=137; 9-11 years old) were subjected to AudioFractions in one 60-minute session. Then, students filled a questionnaire validated by experts with their perceptions about the software and their emotions. Results of the four assessment variables (global, technical, mathematical, musical) plus an affective-emotional assessment, show an excellent reception of AudioFractions.