The acoustics of the catacombs of “San Callisto” in Rome

The word "catacomb" means an underground Christian cemetery, characterized by galleries used for burial. The present study shows the acoustic properties of the catacombs of San Callisto in Rome. The acoustic measurements were made to understand which type of religious functions could have been celebrated in them and in particular if the religious functions were spoken or sung. The catacombs were burial places, but they were also places of reunions and visits to the graves of the martyrs. The catacombs were diffused in the different religions of the various areas of Europe and Mediterranean Asia. The catacombs reached the maximum diffusion with the Christianity. The catacombs were made in subsoil easily removable. The catacombs were generally built through the realization of burrows, with corridors that connected the "cubicles" (rooms with a regular plant realized for the burial). The acoustic measurements were carried out with an explosion of balloons toy. In the catacombs of San Callisto the microphones were put in the corridors, in the cubicles, in the Crypt of Popes and in the Crypt of Santa Cecilia. The measured values of reverberation time are short, due to the presence of tuff walls inside the catacombs