Acoustics in the restoration of Italian historical opera houses: a review

The cultural heritage of Italian historical opera houses is of paramount importance in terms of architecture, music and acoustics. Much is known about the development of their architectural design and the selection of materials that guided the construction of such houses. In fact, traditional technologies are implemented as much as possible when refurbishments are required to ensure the halls maintain their original characteristics. Nevertheless, from an acoustic point of view, the correct approach to safeguard the heritage involves a number of issues which require great insight into the propagation of sound, the interaction with the boundary materials and the occurrence of structural vibrations. Unfortunately, the technical literature on acoustics in the restoration process consists of reports on case histories and pro-vides only limited generalisations. This review develops a comprehensive approach to the topic, covering the most sensitive acoustical issues and their potential impact on the outcome. Together with previous results, fresh data have been added to support the discussion. Moreover, basic and special procedures have been presented to deal with acoustics in the restoration process and, finally, the most important aspects to-be-researched are addressed with special regard to the role of re-radiation from lightweight structures.