After a fire destroyed ‘‘La Fenice’’ Theater of Venice, the Town Council decided it should be rebuilt, being a place of memories for Venetians and people worldwide, committing to the Prefect, named Delegate Commissary, the management of the operation, compiling of a Regulated Contract until reconstruction is finished. He set up an expert workgroup for the drawing up of the Contract which is of main importance in the competition for judging the works. They decided to start the rebuilding of the theater as it was and where it was, preserving at least the internal and external aspects of the ‘‘SaleApollinee’’ halls, and the ‘‘SalaGrande’’ hall. They also decided to give freedom to the designers of the companies invited to the competition, concerning the stage aspects and all the facilities areas (halls for rehearsal, dressing‐rooms, etc.). The problem has been the acoustic characteristics of the ‘‘Sala Grande,’’ which had to appear aesthetically as it was, nevertheless the materials were not going to be the same as before the fire, due to newer safety fireproof requirements. This article deals with all acoustic problems and the several stages of historical‐critical deepening of the acoustics of the theater before the fire, brought into effect during the compiling of the Regulated Contract.