Acoustic models of ancient theatres found in literature are often based on assumptions, both for geometrical and material properties. The influences of these assumptions on modelling results have been assessed in this paper, which is part of the Ancient Acoustics project. Acoustical measurements were conducted in the Odeon of Herodes Atticus, the theatre of Epidaurus and the theatre of Argos, resulting in a large amount of high quality impulse responses per theatre. As part of the Ancient Acoustics project, 3D models were realised of the Odeon of Herodes Atticus and the theatre of Epidaurus to be used in the ray-based room acoustic simulation software 'Odeon'. To ensure the geometric accuracy of our models, measurements were performed with a Total Station theodolite in both theatres. A stepwise evaluation on the influence of the absorption and scattering coefficients is presented for the most accurate geometry using various plausible literature data. Next, the model material settings, for which the trends of simulated result were closest to the acoustic measurements, have been applied to both our own and literature based 3D models with various geometrical accuracies. The run-to-run deviations were taken into account and optimized settings were used, such as the number of rays and the transition order. Finally, the influence of the geometric deviations on selected acoustical parameters are evaluated and presented.
