Speech intelligibility in real and simulated sound fields

The possibility of simulating the sound fields in a theater by electroacoustic means has been investigated using speech intelligibility tests. The sound field simulations have been based on two different concepts. The first simulation experiment used geometrical and statistical acoustics. Corrections were introduced to account for speaker directivity, propagation over the audience, and other factors. The results show that it is hard to simulate the properties using calculated data. This applies especially to an auditorium with a complex wall structure such as the theater tested. There was no correlation with the speech intelligibility results obtained by direct listening in the theater. The second simulation experiment used impulse response data measured in the theater. The simulations were based on the total incident energy and the directions could only be approximated. In this case the correlation between results obtained using direct listening and listening to the simulated sound fields was as high as between results obtained using direct listening and listening to dummy head recordings made in the theater.