Study on the effects of the acoustic scattering on the impulse response in a semi-anechoic room.

The complex sound field in performance spaces, characterized by multiple sound reflections from various surfaces with different absorptive and diffusive characteristics, makes it difficult to deduce the effect of the single interior surface on the room impulse response. In order to obtain more knowledge on this topic, laboratory experiments were performed in a semi-anechoic room. Three different conditions were studied by monaural and binaural room impulse response measurements. Three types of surfaces with different absorptive and diffusive characteristics (flat surface and two differently absorbing concrete blocks with the same geometrical pattern) were placed on the floor during the experiments. The measurements were performed at the same distance from the surface sample at three different distances from the source position. Moreover, for each microphone position eight different orientations of the artificial head were considered. The monaural and binaural impulse responses have been analyzed by comparing the different surface configurations and different orientations of the artificial head. Five objective parameters have been used in this analysis: the ratio between the direct and the reflected sound (DRR), the Time Delay Gap (TDG), the Inter-aural Cross Correlation (IACC), the Inter-aural Time Difference (ITD) and the Inter-aural Level Difference (ILD).