[Partiturogram: (new) tool in the evaluation of an opera roles].

The partiturogram is a tool that was defined in the 1990s by Franco Fussi. It aims to display all the music notes of an opera role as a histogram. Several parameters are then calculated in order to define the vocal profile of the role, as well as help the singer choose from various options. We have decided to use this tool to study Norma and Sonnambula, two roles which were specifically written for the same singer described as a dramatic soprano. Over time, both roles have been allocated to radically different voices. The partiturogram confirms the similarity of the vocal types of both roles, but gives no explanation as to the differences in the casting decisions. We have therefore established its limits, and we have submitted a study including new parameters in order to refine the characterization of roles.