## 4 Results and Discussion
In fact, the different placement of sound sources results in a nonsymmetric distribution of some acoustic parameters, and this behavior is more marked for clarity and STI values, while the prince's box has an excellent sound diffusion and the values are well distributed. The binaural room impulse response was obtained to study the phenomenon of spatial impression in the theatre. Binaural room impulse responses (BRIRs) are calculated using the directivity of omnidirectional decahedron and head-related transfer function (HRTF) of virtual receivers, according to the state-of-the-art of the room simulations [32]. The simulations of the binaural IRs were performed for five relevant receiver positions in the main hall and with the two sound sources A and B on the stage with theatre in the empty configuration. In Figure 12, the result of the early interaural cross-correlation coefficient (IACC) is presented. In this plotted graph, it can be noted that IACC presents quite high values at low and medium frequencies, and this provides a fair immersive listening experience to people. Figure 13 reports a comparison between the results of acoustic simulations with the audience, averaged for each sound source over three groups of receivers: stalls, Prince's box, and galleries (Figure 14). Figure 13 reports the graphs of the most relevant acoustic parameters here considered. For sake of simplicity, the analysis of the Just Noticeable Difference (JND) is reported only for the stalls, where the majority of the receivers are located. The comparison shows that for EDT and T30, differences fall within the limit of the JND range (5%) for the receivers in the galleries, whereas the simulated results in the Prince's box are slightly lower than those simulated in the galleries and outside the JND range of the stalls. These results indicate that the reverberation is uniformly perceived in the stalls and gallery, whereas the Royal box is slightly less reverberant. This enhancement in reverberation brings greater results in terms of musical clarity and speech listening compared to the results in other positions so the prince could appreciate the balance between the voice and the orchestra. The C50 and C80 graphs show that the variability of the parameters is included in the JND range (1 dB). Figure 12: Averaged values of the interaural cross-correlation coefficient (IACC) simulated in five relevant receiver positions in the hall without audience. Moreover, the study of the separate results for the two sound sources A and B on the stage is reported in Figure 15.  
Figure 14: Plan of the theatre with the three groups of receivers: stalls in yellow, gallery in blue, and Prince’s box in red. Figure 13: Simulated acoustic parameters (**(a)** EDT, **(b)** T30, **(c)** C50, and **(d)** C80) for the theatre with the audience in the main hall. The values are subdivided into three groups (stalls, Prince’s box, and gallery) and averaged over the corresponding receivers. The error bars (Just Noticeable Difference, JND) are reported for receivers in the stalls. The acoustic parameters were calculated only for the receivers in the Royal box and with the presence of the audience. Changes in reverberation are very small, especially for the early decay time parameter, where the differences between the two sound sources fall within the limit of the JND range (5%) and the early reflections are slightly perceived. Moreover, the T30 graph shows that the variability of the parameter is included in the JND range (5%) and there isn't a relevant difference between the perception of the late reflections produced by the sound source A and by the sound source B.  
Conversely, the position of the source on the stage influences much more the speech and music perception in the Prince box. Especially, the C50 graph shows that the values with the sound source in A and B fall within the limit of the JND range (5%) and speech listening with the sound source in A is better than position B.