In this work we present the results from an empirical research in many different ages. In this research we want to record and then to classify the students' ideas of Primary and Secondary school, but also teachers' ideas of Primary education for the way a sound is propagated in various materials. This effort to the constitution of mental models will help us to point out and discuss for the difficulties encountered by them in the understanding of these concepts and phenomena of sound. This research for the ideas (from the 50 respondents of our sample) has led us to the constitution of the three mental models for the propagation of a sound (the propagated «disturbance», the flow of «sound» and the moving «entity»).