Our goal was to verify the hypothesis that musical excerpts are perceptually structured within dimensions of opposite properties. Participants, 9 expert musicians, were asked to complete three tasks when listening to 8 short sections of jazz music. In the first task, participants were asked to inter-observatively define a list of opposite dimensions, which they judged sufficient to form a complete description of the events they were listening to. In the second task participants were asked to choose, within the list set in the first task, which dimensions they clearly recognized in each of the 8 musical sections. In the third task participants were asked to indicate when one property changed into the opposite by drawing a marker in the musical sheet, for each of the previous recognized dimensions. Results confirmed the possibility to state the direct organization within structures of opposition of the perceived identity of musical excerpts.