The objective of this work (under WP5 of the ERATO project) has been to create and analyse acoustical models of the selected theatres and odea by means of a computer simulation programme (named ODEON). Models have been created of the monuments both as originally built (to the extent that this is known), in their present state (as ruins), and with the temporary stages and scenery often applied when these spaces are used as performance venues today. Hereby, it has become possible to quantify the acoustical properties of the ancient theatres and odea in each condition leading to valuable information regarding the acoustical consequences and degree of authenticity of permanent restorations and temporary amendments. Moreover, based on recorded samples of authentic style music/speech (resulting from WPs 3 and 4), the simulations also have produced audible sound demonstrations of virtual performances with a high degree of acoustic realism. These sound files have been integrated with the visual restorations (WP 6) to form the audio in 3D virtual realizations of performances in the selected venues (WP7). The simulations of the acoustic conditions have been calibrated through comparison of the calculated results from the monuments in their present state with the actually measured acoustic data (from WP4). Also comparisons with the scale model studies contained in WP4 have ensured a high degree of accuracy in both modelling techniques supporting a deeper insight into the acoustics of ancient theatres and odea in general.