Evolution of Some Microphone Arrays in Sound Field Reproduction. Application Inside Two Historical Theatres

Performing arts spaces characterize a specific group of buildings always subject to intense studies under architectural other than acoustics point of view. In Italy, the acoustics of historical theatres, as Baroque Opera houses and Renaissance concert halls, is nowadays considered the most important physical aspect of the architectural heritage. This paper analyzes the acoustical characteristics of some important Italian theatres. In order to precisely compare the analogies of the selected theatres, only the architecture realized during the 18th century has been considered. The acoustics features have been obtained by using a pre-equalized omnidirectional sound source, which emitted an exponential sound signal (ESS) acquired by a dummy head and a B-Format microphone. This technique satisfies the standard requirements of the ISO 3382:2009 and has been compared with the innovative process realized by using a 32-channel individually controlled microphone (i.e. em32 Eigenmike®). This new generation of the microphone is able to create a 3D auralization by synthesizing any real-time variable directivity pattern. In this way, both graphical analysis and 3D sound playback can be the resulting methods of how to show the room impulse response (RIR) data measured inside any performing arts space.