Often the classrooms are located in historical buildings, where for aesthetic and historical reasons it is difficult to install sound-absorbing panels for acoustic corrections; the classrooms are not regular in shape and the ceilings are not level [1], [2]. To improve the acoustic characteristics of the classrooms, sound-absorbing materials must be installed in an appropriate manner, but with non fixed structures, as they are historical buildings. Odeon, a compliant software for architectural acoustics was used to identify the type of material to be used, and where to find the geometrical position of the most effective location of acoustic correction.

To produce a case study, classrooms situated in the Faculty of Architecture of the Seconda Università di Napoli (SUN) were selected. The classrooms were all located in the historic building, each irregularly shaped and had vaulted ceilings, the walls were smooth as they were plastered [3]. For each classroom measurements were taken on acoustic characteristic as the reverberation time (T30), the Definition (D50) and the Speech Transmission Index (STI). With the aid of the Odeon software, the programmed has tried to find the location where to install the panels to reduce reverberation time and improve the acoustics characteristic, preserving aesthetics and following historic preservation instructions. The results of the acoustic measurements for the classrooms and the relative acoustic correction of varying positions of the sound-absorbing panel are demonstrated.