On the use of 3d auralisation to evaluate room acoustic enhancement in auditorium restoration

The acoustic quality in auditorium and concert halls is normally evaluated by the measurements of Impulse responses (monaural, binaural or even MIMO). The subjective evaluation is often obtained by convolving anechoic music with the measured IRs. The psycho-acoustical experiment is achieved using a virtual sound field representation. At the University of Bologna, the listening room Arlecchino includes Ambisonics and stereo dipole techniques for playback. In this paper, two different Italian opera houses and two Japanese concert halls were analysed. They were the Teatro Nuovo in Spoleto (Italy), the Teatro Alighieri in Ravenna (Italy), the Kirishima International Musical Hall in Kagoshima (Japan), and the Tsuyama Musical Cultural Hall in Okayama (Japan). The similarity between real and virtual sound fields, obtained with stereo dipole technique, was evaluated by comparing different acoustic parameters calculated by real and virtual sound fields, in the four halls in different designed configurations. Finally, the stereo dipole technique was added to the ambisonic methodology to reproduce the sound fields for the psycho-acoustical experiment. The dual stereo-dipole technique using two kinds of cross-talk cancelling filters can be one of the solutions for improving the acoustical quality of home theatre.