This study shows an investigation on the modeling level of detail of diffusive surfaces, which strongly influences the efficiency of geometrical acoustic based software. One diffusive condition of the lateral wall of a shoebox hall has been modeled as (a) flat surfaces with surface scattering coefficient and (b) three-dimensional relief including edge diffraction. The analysis has been performed by comparing the conventional acoustic parameters, which showed no significant differences, and by subjectively investigating the sensitivity of listeners to both modeling approaches, which highlighted that perceptual differences related to reverberance and spaciousness are clearer when using the modeling approach (b).