The acoustic of Roman theatres in Southern Italy and some reflections for their modern uses

Ancient Roman theatres represent a unique cultural heritage which is still used nowadays to host a variety of cultural activities and performances. Acoustic measurements show that the acoustics of these theatres does not always support the listening of music, which is common in modern performances. Although the acoustics of these theatres for modern use performances may be challenging, this cultural heritage offers a unique experience to the audience who can assist to a performance on the same seats once used by Romans. Nowadays, these unroofed theatres, whose walls behind and at the sides of the stage have rarely been restored, are often criticized for the weak sound strength. Moreover, these theatres are often exposed to urban modern background noise. The significant sound absorption due to the presence of the audience on the seating area (named cavea) and to the tapestries used in modern scenes makes challenging to support the acoustic reverberation in these theatres. In this paper, these aspects are described focusing on five ancient Roman theatres located in Southern Italy. The study reports acoustic measurements followed by virtual simulation results. As it was impossible to perform acoustic measurements with full audience occupancy, the presence of the audience was simulated using room acoustic software. The paper compares the acoustic characteristics of these five theatres considering their architectural characteristics, and discusses the role that the material used for their restoration had on their acoustics. Finally, some considerations about some reversible interventions to improve the acoustics of these ancient theatres for modern uses are reported.