This qualitative study has evolved from an ambition to find methods of increasing the possibilities of creating a stronger dialectics between planned music activities and spontaneous sound creating actions. The aim of this study is thus to describe and analyse children´s spontaneous sound creating actions in unplanned activities as a base for future practical didactic procedures in preschools.The concept of music is expanded to include actions in order to make sound and actions that create sounds and the children´s actions are described and analysed through different subjects´ perspectives by means of a posthumanist intra-active perspective. The importance of materiality as well as the context which constitutes children´s everyday life in preschool is shown through the analysis. The children´s sound creating actions are closely related to continuous processes of becomings in which children, materiality, and also the researcher become different in themselves through intra-action. The materiality, the rooms, the size of the group of children and time can be identified as performative agents that enable several potential outcomes and a variety of contents in children´s spontaneous sound creating actions. The study also shows how the children mainly explore the basic music element timbre. This opens discussions regarding didactic implications and new approaches towards the practical staging of music activities in preschool.