The accuracy of predicted acoustical parameters in ancient open-air theatres: A case study in Syracusae

Nowadays, ancient open-air theatres are often re-adapted as performance spaces for the additional historical value they can offer to the spectators' experience. Therefore, there has been an increasing interest in the modelling and simulation of the acoustics of such spaces. These open-air performance facilities pose several methodological challenges to researchers and practitioners when it comes to precisely measure and predict acoustical parameters. Therefore this work investigates the accuracy of predicted acoustical parameters, that is, the Reverberation Time (T-20), Clarity (C-80) and Sound Strength (G), taking the ancient Syracusae open-air theatre in Italy as a case study. These parameters were derived from both measured and simulated Impulse Responses (IR). The accuracy of the acoustic parameters predicted with two different types of acoustic software, due to the input variability of the absorption and scattering coefficients, was assessed. All simulated and measured parameters were in good agreement, within the range of one "just noticeable difference" (JND), for the tested coefficient combinations.