Acoustics and spatial sound distribution in the theatre comunale in Bologna, Italy

The acoustic quality of concert halls is extremely relevant for the modeling and simulation of the global music experience and for improving the acoustic design of music spaces. Furthermore, the acoustic characteristics of historical opera houses are considered to be one of the most important intangible elements of the cultural heritage of Italian history. An important Italian opera house is the theatre “Comunale” in Bologna (designed in the 18th Century by Galli Bibiena), and has a particular characteristic: the shape of the balconies and the materials with which they were constructed are different from those of a classical Italian opera house. This special feature of the balconies affects the listening conditions related to the position of sound sources on the stage and in the orchestra pit. This study investigates the acoustic properties of this important theatre in order to reproduce the sound properties by means of a 3D auralization. For describing the spatial sound characteristics of the hall, an experimental campaign was carried out. An omnidirectional, pre-equalized sound source was installed in the orchestra pit and on stage, and a dummy head was put in several listening positions on the balconies and in the stalls, accomplished with a B-format (soundfield) microphone. Moreover, the special features of the ACF (autocorrelation function) and the IACC (InterAural Cross Correlation) and other acoustic parameters were measured experimentally in order to reproduce them in the listening room “Arlecchino” at the laboratory of University of Bologna, by means of the Stereo Dipole and Ambisonics technique. The main results from the experiments are reported in this paper.