Acoustics of opera houses: a cultural heritage

In the paper the concept of acoustical heritage of historical opera houses is expounded. To support the safeguard of this heritage, guidelines for making acoustical measurements inside historical theatres were developed with the aid of a group of international specialists. The paper reports on a test session inside the Teatro Comunale of Ferrara where these guidelines have been put into practice. The way they have been applied is described and some possible changes to be introduced in the document are outlined.