Sensitivity testing of room acoustic models on changes of material and environmental parameters, as well as sound source and receiver locations is very important for the validity of the calibration of the models to the measurement results obtained in the existing object. Awareness of the sensitivity of the acoustic model is also very important in supervising the renovation of existing objects. It helps to adapt corrections in the modeling and outfit of the object during successive stages of disassembly and assembly of the elements of the interior. In the paper analysis of the influence of the sound absorption and the sound scattering coefficient changes on the acoustic parameters of the room is presented. Reverberation time and sound clarity were especially investigated. A group of materials was selected, for which measurement or modeling accuracy had crucial importance for the correctness of the room acoustic parameters prediction. Special attention was paid to the sound scattering coefficient. Its influence on averaged as well as locally analyzed parameters was investigated.