Advances in psychoacoustics through the years, have made it possible to evaluate the acoustical quality of a room, based on several numerical parameters that have been developed. Even though there is not a total agreement about which parameters are truly important, some of them are accepted by most of the acousticians. When designing a concert hall, ray-tracing softwares can be used to calculate some of these parameters. However,some input data carry some uncertainties. Available data for absorption coefficients have to be used carefully and, beyond that, there is not a standardized recommendation for measuring diffusion coefficients, nor a data base for this parameter. This paper presents a comparison of a room simulated with one of the commercial softwares available (RAYNOISE), and the measured parameters in this same room, using Maximum Length Sequence (MLS). Discrepancies over the results are investigated and analyzed.